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PubMed2004

Menopausal increases in pulsatile gonadotropin-releasing hormone release in a nonhuman primate (Macaca mulatta).

Reproductive function in all vertebrates is controlled by the circhoral release of the neuropeptide, GnRH, into the portal capillary system leading to the anterior pituitary. Despite its primary role in sexual maturation and the maintenance of adult reproductive function, changes in the concentrations and pattern of GnRH release have not yet been reported in any primate species during the menopausal transition and postmenopause. Such knowledge is essential for ascertaining both the mechanisms for, and consequences of, the menopausal process. Here we used a push-pull perfusion method to measure and compare the parameters of pulsatile GnRH release in adult rhesus monkeys at 8.4 +/- 1.5 yr (young adult females, early follicular phase, n = 6) and 28.8 +/- 0.3 yr (aged females, n = 4, of which two monkeys were in the menopausal transition, and two were postmenopausal). Our results demonstrate that: 1) GnRH release is pulsatile in both young and aged monkeys; 2) mean concentrations of GnRH increase during reproductive aging; and 3) GnRH pulse frequency does not differ between aged monkeys and young monkeys in the early follicular phase. We conclude that not only do GnRH neurons have the continued capacity to release GnRH in a pulsatile manner but also they can do so with enhanced GnRH levels in aged primates. To our knowledge, this is the first direct demonstration of elevated pulsatile GnRH concentrations in a primate species during reproductive senescence, a result that may have implications for menopausal symptoms.

Aging↗
PubMed2005

Firing pattern and rapid modulation of activity by estrogen in primate luteinizing hormone releasing hormone-1 neurons.

We have shown previously that cultured LHRH-1 neurons, derived from monkey olfactory placode region, exhibit pulsatile LHRH-1 release at hourly intervals and spontaneous intracellular calcium oscillations, which synchronize at a frequency similar to LHRH-1 release. Brief application of estrogen induced a rapid increase in the frequency of intracellular calcium oscillations and the frequency of synchronizations. The estrogen-induced frequency of intracellular calcium oscillations was mediated by estrogen receptors (ER), whereas the frequency of synchronizations was not mediated by ER. In the present study, we further examined the rapid action of estrogen using patch-clamp recording in primate LHRH-1 neurons. Cell-attached patch-clamp recording showed that LHRH-1 neurons exhibited monophasic or biphasic action currents that were sensitive to an increase in extracellular K+ and the sodium channel blocker tetrodotoxin. The majority (90%) of LHRH-1 neurons showed irregular firing patterns composed of bursts and irregular beatings of action currents, which further formed a "cluster" firing pattern. Brief application of 17beta-estradiol (1 nM) increased the firing frequency and burst duration of LHRH-1 neurons with a latency of 60-120 sec for up to 25 min. ICI182,780, an ER antagonist, blocked the 17beta-estradiol-induced increase in the firing activity of LHRH-1 neurons. These results suggest that 1) primate LHRH-1 neurons exhibit complex firing patterns composed of activities with different time domains, 2) estrogen causes rapid stimulatory action of firing activity, and 3) this estrogen action is mediated by ER in primate LHRH-1 neurons.

Animals↗
PubMed1984

Stimulatory effect of estrogen on prolactin secretion from primate pituitary cells cultured on extracellular matrix and in serum-free medium.

To determine the direct effect of estrogen on primate PRL production, cultures of dispersed monkey pituitary cells were established in serum-free medium on an extracellular matrix secreted by bovine corneal endothelial cells. Medium PRL levels were monitored by RIA every fourth day after plating. PRL secretion was maintained for 24-28 days in cultures from female monkeys and for 16-20 days in cultures from male monkeys using a 1:1 mixture of Dulbecco's Modified Eagle's Medium H-16 (DME) and Ham's F-12 medium (F12) supplemented with insulin (I), transferrin (T), PTH, T4, fibroblastic growth factor, putrescine, ethanolamine, lipids (oleic, lecithin, and cholesterol), selenium (S), and cadmium (C). The mean percent changes in medium PRL of seven cultures of female pituitaries and two cultures of male pituitaries compared to the first sample (day 4) were: +26% (day 8), +17% (day 12), +11% (day 16), -4% (day 20), -13% (day 24), and -24% (day 28). The elimination of supplements except ITSC did not appear to affect PRL secretion in a culture of cells from ovariectomized female monkeys, but secretion in two cultures of male pituitary cells declined after day 12. Addition of 10(-8) M estrogen to three cultures of male pituitary cells in DME/F12 containing all supplements significantly elevated PRL over control levels and, in addition, prevented the decline observed in control wells of one culture for 28 days. In two cultures of male pituitary cells maintained in DME/F12 plus ITSC, estrogen significantly elevated medium PRL levels for the 28-day period, but did not totally prevent the decline observed in control wells after day 12. In two cultures of female pituitary cells maintained in DME/F12 plus all supplements and in three cultures of female pituitary cells maintained in DME/F12 plus ITSC, medium PRL levels were significantly higher when estrogen was present. However, estrogen addition had no effect on the pattern of PRL secretion in two cultures of female pituitary cells maintained in DME/F12 plus 10% charcoal-treated fetal calf serum. In five of seven cultures, the presence of estrogen for 28 days resulted in a significantly higher cellular content of PRL. These experiments suggest that estrogen can directly increase PRL production by primate mammotrophs and that this effect is best seen in serum-free medium. In summary, extracellular matrix and serum-free medium provide an adequate in vitro environment for studies of PRL processing by primate pituitary cells for periods up to 1 month. In this system, estrogen effectively elevated PRL secretion and cell content.

Animals↗
PubMed1992

Role of luteinizing hormone in the expression of cholesterol side-chain cleavage cytochrome P450 and 3 beta-hydroxysteroid dehydrogenase, delta 5-4 isomerase messenger ribonucleic acids in the primate corpus luteum.

It is well established that LH has an obligatory role in the acute production of progesterone by the primate corpus luteum in vivo because interruption of LH support to the corpus luteum at any time during the luteal phase is accompanied by an immediate and sustained fall in serum progesterone concentrations. However, recent studies have demonstrated that maximal steroidogenic capacity of cultured human luteal cells and maximal levels of messenger RNAs (mRNAs) for cholesterol side chain cleavage cytochrome P450 (P450scc) and 3 beta-hydroxysteroid dehydrogenase, delta 5-4 isomerase (3 beta-HSD) in luteal tissue are observed shortly after luteinization and decline thereafter throughout the remainder of the luteal phase. These findings would suggest that the role of LH in the acute regulation of progesterone production may differ from its role in the expression of mRNAs for steroidogenic enzymes. We initiated the current studies to define the role of LH upon the expression of mRNAs for P450scc and 3 beta-HSD by the primate corpus luteum. For this purpose, we treated cynomolgus monkeys with a potent GnRH antagonist for 1, 2, and 3 days during the luteal phase of the menstrual cycle and measured levels of mRNAs for P450scc and 3 beta-HSD in corpora lutea. Treatment of monkeys with the GnRH antagonist reduced bioactive LH concentrations to less than 5 ng/ml by 48 h of treatment, and LH concentrations remained less than 5 ng/ml thereafter. Serum progesterone concentrations were reduced by 74% after 1 day of antagonist treatment, 88% after 2 days of antagonist treatment, and by more than 95% after 3 days of GnRH antagonist treatment. Although progesterone secretion was markedly diminished after 24 h of antagonist treatment, there were no differences in mRNAs for P450scc and 3 beta-HSD between antagonist-treated and control animals. However, mRNAs for P450scc and 3 beta-HSD were significantly (P < 0.05) reduced after 2 days of antagonist treatment and were nearly nondetectable after 3 days of antagonist treatment. These results demonstrate a temporal dissociation of the effects of LH on the acute regulation of progesterone secretion and the maintenance of specific mRNAs involved in progesterone production. Nonetheless, the results clearly show that LH is required for the continued expression of mRNAs for P450scc and 3 beta-HSD by the primate corpus luteum.

3-Hydroxysteroid Dehydrogenases↗
PubMed1993

Insulin-like growth factor binding proteins in sera of pregnant nonhuman primates.

Insulin-like growth factors (IGFs) are mitogenic peptides that are important for fetal and maternal tissue growth during pregnancy. They circulate complexed primarily with a serum binding protein, IGFBP-3, which regulates the availability of the IGFs to their target tissues. We previously reported that in pregnant women, serum IGFBP-3 levels, assessed by Western ligand blotting, decline markedly beginning at 6 weeks gestation due to a circulating protease that cleaves IGFBP-3 into a 29-kilodalton (kDa) protein and lower mol wt (M(r)) fragments. In the current study, we compared IGFBP profiles, IGFBP-3 and IGFBP-1 levels, and IGFBP protease activities in sera from pregnant and nonpregnant women, baboons, and rhesus monkeys, using Western ligand blotting, IGFBP-specific immunoassays, IGFBP-3 protease assay, and zymographic gel electrophoresis. Serum IGFBP profiles in nonpregnant human and nonhuman primates were similar and were not cycle-dependent. IGFBP-3 (37-43 kDa), IGFBP-2 (31 kDa), and IGFBP-1 (28 kDa) were identified in all three species using IGFBP-specific human antisera. A 24-kDa IGFBP was also present and is believed to be IGFBP-4. Serum IGFBP-1 levels increased throughout gestation in human and nonhuman primates. Serum IGFBP-2 and putative IGFBP-4 were barely detectable in all three species from midgestation to term, but increased several days postpartum. In contrast, serum IGFBP-3 profiles differed markedly between species during gestation. Rather than the decrease seen in human pregnancy serum, there was an increase in circulating IGFBP-3 levels in nonhuman primates. Furthermore, for both baboon and rhesus monkey, the M(r) of serum IGFBP-3 was about 2 kDa greater in pregnant than in nonpregnant animals, and deglycosylation studies suggested that the higher M(r) forms may be alternatively glycosylated or may have a unique primary structure. As in nonpregnant women, serum IGFBP-3 protease activity was absent in nonpregnant and pregnant baboons. However, rhesus monkey serum contained a calcium-dependent protease that cleaved recombinant human IGFBP-3 into unique fragments, compared to the human pregnancy enzyme. Unlike human pregnancy serum, which proteolyzes IGFBP-3, in human nonpregnancy serum, rhesus serum incubated under similar conditions did not result in proteolysis of rhesus IGFBP-3, suggesting that the IGFBP-3 protease in human pregnancy serum is not present in the circulation of the rhesus monkey. To assess proteolytic activity in these sera, zymographic polyacrylamide gel analysis, using gelatin as a substrate, was performed. A minor band of proteolytic activity (72 kDa) was observed in all three species throughout gestation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Noncoordinated expression of luteal cell messenger ribonucleic acids during human chorionic gonadotropin stimulation of the primate corpus luteum.

In nonfertile cycles, the absolute steroidogenic capacity of the primate corpus luteum, as reflected in the expression of messenger RNA (mRNA) for the progesterone biosynthetic enzymes cytochrome P450 cholesterol side-chain cleavage (P450SCC) and 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), progressively declines until luteal regression. Despite this progressive loss in luteal cell function, the elaboration of CG by the implanted blastocyst is able to prolong the functional lifespan of the corpus luteum. It was the purpose of this study to investigate the relationship between aging of the primate corpus luteum and the cellular mechanisms by which the decline in luteal cell function is arrested by CG. Corpora lutea were obtained from cynomolgus monkeys on days 11 or 16 of the luteal phase after a 7-day treatment period with increasing doses of human CG (hCG) given intramuscularly beginning on days 5 or 10. Corpora lutea were also obtained from control animals on days 5, 10, 11, and 16 of the luteal phase. Human CG treatment significantly (P < 0.05) elevated both serum progesterone and estradiol levels throughout the treatment period; however, progesterone production in animals treated with hCG late in the luteal phase (days 10-16) steadily declined after the third treatment day. Expression of mRNA for P450SCC and 3 beta-HSD was markedly stimulated (P < 0.05) by hCG treatment early in the luteal phase. However, 3 beta-HSD message levels in corpora lutea from animals treated with hCG on days 10-16 were not different from those of day-16 control corpora lutea, whereas P450SCC mRNA was only minimally stimulated. There was a dramatic (P < 0.05) increase in mRNA levels for the aromatase enzyme and low density lipoprotein receptor in animals given hCG in both the early and the late luteal phase. In conclusion, there appears to be a differential responsiveness of the primate corpus luteum to hCG stimulation dependent upon luteal age. The loss in responsiveness to hCG in terms of maintenance of mRNA levels is reflective of the inability of the late luteal phase corpus luteum for continued progesterone biosynthesis in the face of heightened luteotropic stimulation.

3-Hydroxysteroid Dehydrogenases↗
PubMed1996

Functional maturation of the primate fetal adrenal in vivo. II. Ontogeny of corticosteroid synthesis is dependent upon specific zonal expression of 3 beta-hydroxysteroid dehydrogenase/isomerase.

Cortisol, produced by the primate fetal adrenal, regulates the maturation of organ systems necessary for extrauterine life. During most of primate pregnancy, however, the fetal adrenal lacks the enzyme 3 beta-hydroxysteroid dehydrogenase/isomerase (3 beta HSD), which is essential for cortisol synthesis. Therefore, we used immunohistochemistry and in situ hybridization techniques to investigate the developmental expression of 3 beta HSD in the fetal rhesus monkey adrenal from 109 days' gestation until term (165 +/- 5 days) and assessed the role of ACTH in the induction of its expression and localization. We also examined whether ACTH regulates the expression of two other steroidogenic enzymes, cytochrome P450 cholesterol side-chain cleavage (P450scc) and P450 17 alpha-hydroxylase, 17/20-lyase (P450c17), in the fetal rhesus monkey adrenal. To stimulate ACTH secretion from the fetal pituitary in vivo, we administered metyrapone to late gestation fetal rhesus monkeys for 3-7 days. Adrenals were collected from untreated fetuses at 109-125 days (n = 5), 130-148 days (n = 7), 155-172 days (n = 4), and after metyrapone treatment at 135-137 days (n = 4). The cortical width and total amount of 3 beta HSD staining were measured using an image analysis system. 3 beta HSD was localized primarily in the definitive zone cells of the adrenal from fetuses between 109-148 days, whereas at term (155-172 days), 3 beta HSD was localized in both definitive and transitional zone cells. The cortical width and total amount of 3 beta HSD staining in the adrenal increased significantly (P < 0.05) between 148 days (137 +/- 14 microns and 3,689 +/- 522 grains) and 155 days (315 +/- 61 microns and 7,321 +/- 2,008 grains). Interestingly, in metyrapone-treated fetuses at 135-137 days, 3 beta HSD messenger RNA (mRNA) and protein were localized extensively in both the definitive and transitional zones, a pattern seen only in term fetal adrenals in untreated animals. In addition, metyrapone treatment significantly (P < 0.05) increased cortical width (386 +/- 95 microns) and total 3 beta HSD immunostaining (29,063 +/- 13,692 grains) compared with age-matched controls. In contrast to 3 beta HSD, P450scc mRNA was detected in the definitive, transitional, and fetal zones, and its expression was not altered after metyrapone treatment. P450c17 mRNA was detected in the transitional and fetal zones, and the relative abundance was greater in the transitional zone. The relative abundance of P450c17 mRNA was increased in the fetal zone after metyrapone treatment. In summary, at term or after metyrapone treatment, expression of 3 beta HSD is induced in the transitional zone of the fetal rhesus monkey adrenal gland, an indication of functional maturation of the primate adrenal cortex. These data suggest that the ontogenetic increase in fetal pituitary ACTH secretion plays an important role in the induction of 3 beta HSD expression in the transitional zone.

Adrenal Cortex Hormones↗
PubMed1997

A second form of gonadotropin-releasing hormone (GnRH) with characteristics of chicken GnRH-II is present in the primate brain.

The primate brain was thought to contain only the GnRH known as mammalian GnRH (mGnRH). This study investigates whether a second form of GnRH exists within the primate brain. We found that brain extracts from adult stumptail and rhesus monkeys contained two forms of GnRH that were similar to mGnRH and chicken GnRH-II (cGnRH-II) based on the elution position of the peptides from HPLC and on cross-reactivity with antisera that are specific to mammalian or chicken GnRH-II in RIAs. The fetal brain of rhesus monkeys also contained mGnRH and a cGnRH-II-like peptide by the same criteria. Immunocytochemistry with a cGnRH-II-specific antiserum in adult and fetal rhesus monkeys showed immunopositive neurons generally scattered in the periaqueductal region of the midbrain, with a few positive cells in the posterior basal hypothalamus. Neurons immunopositive for cGnRH-II were fewer in number and smaller in size, with less defined nuclei and thinner neurites compared with those for mGnRH. Administration of synthetic cGnRH-II to adult rhesus monkeys resulted in a significant increase in the plasma LH concentration during the luteal phase of the menstrual cycle, but not during the midfollicular phase. We conclude that the primate brain contains mGnRH and a cGnRH-II-like molecule, although the function of the latter is unknown.

Aging↗
PubMed2003

Functional differentiation of the placental syncytiotrophoblast: Effect of estrogen on chorionic somatomammotropin expression during early primate pregnancy.

Estrogen stimulates morphological and functional (i.e. steroidogenesis) differentiation of the primate placental trophoblast, and with advancing gestation there is an increase in estrogen and placental chorionic somatomammotropin (CS) mRNA and protein levels. To examine whether CS formation is regulated by estrogen, placental villous trophoblast CS was determined in baboons in which estradiol levels in uterine vein were increased 2- to 3-fold (P < 0.01) on d 60 of pregnancy (term = 184 d) by administration of aromatizable androstenedione on d 30-59 or estradiol benzoate on d 45-59 of gestation. Androstenedione and estradiol treatment resulted in a 75% decrease (P < 0.01) in placental whole villous CS-3 mRNA and CS protein levels, determined by Northern and Western blot analysis, on d 60, and a corresponding decrease in syncytiotrophoblast CS protein and maternal serum CS levels. In contrast, placental villous Delta(5)-3beta-hydroxysteroid dehydrogenase, 11 beta-hydroxysteroid dehydrogenase-2, and P-450 aromatase protein levels were unaltered by androstenedione or estradiol treatment. Collectively, these results suggest that, in elevated levels, estrogen suppressed CS formation by villous syncytiotrophoblast during the first one third of primate pregnancy. Therefore, estrogen has very different and specific actions on steroid and peptide hormone biosynthesis within the placental trophoblast, which we propose are important in regulating placental function and promoting fetal-placental development in the primate.

3-Hydroxysteroid Dehydrogenases↗
PubMed2004

Prostaglandin dehydrogenase and prostaglandin levels in periovulatory follicles: implications for control of primate ovulation by prostaglandin E2.

Prostaglandin (PG) E2 produced by the periovulatory follicle in response to the midcycle LH surge is essential for successful ovulation in primates. Granulosa cells express the PG synthesis enzyme cyclooxygenase-2 in response to the LH surge, but elevated cyclooxygenase-2 mRNA levels precede rising follicular fluid PGE2 levels by 24 h. Therefore, PG metabolism may play a significant role in regulating follicular concentrations of PGE2 during the periovulatory interval. To test this hypothesis, granulosa cells, follicular fluid, and whole ovaries were obtained from adult monkeys receiving exogenous gonadotropins to stimulate development of multiple, large follicles at times spanning the 40-h periovulatory interval. Ovarian expression of the NAD+-dependent 15-hydroxy PG dehydrogenase (PGDH) was assessed by RT-PCR, Western blotting, and immunohistochemistry. PGDH mRNA levels were low in granulosa cells obtained 0 h after hCG, rose 10-fold 12 h after hCG, and were not different from 0 h by 24-36 h after hCG administration. Granulosa cell PGDH protein was present 0-12 h after hCG but was low/nondetectable 36 h after hCG administration. Follicular fluid PGE2 levels were low at 0-12 h, slightly higher at 24 h, and then rose 10-fold to peak at 36 h hCG. Levels of biologically inactive PGE2 metabolites in follicular fluid were also low at 0 h but elevated at 12-24 h after hCG, times at which PGE2 levels remain low. Therefore, PGDH is present in the primate periovulatory follicle in a pattern consistent with modulation of follicular PGE2 levels during the periovulatory interval, supporting the hypothesis that gonadotropin-regulated PGDH plays a role in the control and timing of ovulation in primates.

Animals↗
PubMed1980

Evidence that human growth hormone is a potent lactogen in primates.

To help determine if human GH (hGH) plays a physiological role in normal mammary function or diseases of the human breast, a study was undertaken to examine the lactogenic potency of hGH in a subhuman primate system. hGH was previously considered a relatively weak lactogen when tested in avian crop sac and rodent mammary assays. The effect of hGH on the production of alpha-lactalbumin in organ cultures of primate mammary tissue was compared with the effect of equal concentrations of ovine PRL (oPRL). Mammary tissues from seven adult rhesus monkeys were maintained in culture for 9 days (medium changed every 3 days) without and with oPRL or hGH in doses ranging from 30-1000 ng/ml. hGH was consistently more effective than oPRL in the stimulation of alpha-lactalbumin production in over 90% of the cases. For example, mean (+/- SEM) alpha-lactalbumin production at the 6-day time period in response to 1000 ng/ml hormone was 12.9 +/- 3.3 ng/ml for oPRL and 61.9 +/- 18 ng/ml for hGH. Overall, it was calculated that hGH had 328% the potency of oPRL in adult rhesus monkey mammary tissue. In pigtail macaques, hGH was also a more potent stimulant of alpha-lactalbumin production than oPRL, but the differences wer not as great as in rhesus monkeys. alpha-Lactalbumin in medium was higher in hGH-containing dishes than in those containing oPRL in over 85% of the cases. It was calculated that the lactogenic potency of hGH in macaque tissue was 160.5% that of oPRL. The differences between species were significant. These results indicate that hGH is a more effective lactogen in subhuman primates than oPRL and suggest the possibility of GH may be a lactogen which has physiological importance.

Animals↗
PubMed1986

Acute parathyroid hormone secretory dynamics: hormone secretion from normal primate and adenomatous human tissue in response to changes in extracellular calcium concentration.

PTH secretion has been evaluated extensively using short term incubation techniques, but these methods cannot be used to adequately evaluate the early phases of PTH secretion. We developed a dispersed cell perifusion system to study these acute secretory events. Responses to low calcium conditions were studied using dispersed cells from normal primate and adenomatous human parathyroid tissue. When these cell were perifused with 1.0 mM calcium medium, PTH secretion was stable, but increased within minutes in a dose-dependent manner in response to a lowering of extracellular calcium concentrations. Similarly, PTH secretion quickly declined when cells were exposed to higher extracellular calcium concentrations. In studies of cells from 11 human adenomas, the mean maximum secretion in response to 0.25 mM calcium conditions was 587 +/- 330% (+/- SD) of that in response to 1.0 mM calcium. The magnitude of the response to low calcium stimulation was variable, and cells from two additional adenomas failed to respond to low calcium stimulation despite responses to other secretogogues. Variation in the rate of increase in stimulated PTH secretion was also found among the adenomas examined (128 +/- 95% of baseline/min), and the rate of increase in PTH release and the eventual maximum rate of release were positively correlated. In studies of cells from 4 normal primates (rhesus macaque), the maximum response to 0.25 mM Ca2+ (544 +/- 118% of baseline) and the rate of increase in PTH secretion (95 +/- 35% of baseline/min) were similar to those in adenomatous human tissue. These results indicate that 1) acute PTH secretion can be studied in vitro, and that it appears to be similar to the in vivo process; 2) there is a wide variation among adenomatous tissues in the magnitude of secretion stimulated by low calcium concentrations; 3) in addition to varied magnitude of secretion, the rate at which hormone secretion increases in response to a low calcium stimulus varied among adenomas; and 4) PTH secretion from human adenomatous tissue is similar to that from normal primate tissue in both the rate and magnitude of response.

Adenoma↗
PubMed1988

Phenotypic diversity of the cellular 1,25-dihydroxyvitamin D3-receptor interaction among different genera of New World primates.

High serum of 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] concentrations and target organ resistance to the hormone are characteristic findings in some New World primates (platyrrhines). We examined the abilities of cultural dermal fibroblasts from individual platyrrhines of four different genera, Aotus, Alouatta, Pithecia, and Saguinus, to internalize and respond to 1,25-(OH)2D3 in an attempt to identify possible phenotypic heterogeneity in the 1,25-(OH)2D3-receptor interaction among them. Results were compared to those from two Old World primates (catarrhines), Pan troglodytes and Pongo pygmaeus. Compared to catarrhine cells, cells from Alouatta, Pithecia, and Saguinus demonstrated 1) a 10-fold decrease in [3H] 1,25-(OH)2D3 internalization capacity; 2) a 2- to 5-fold increase in the apparent internalization constant [3H]1,25-(OH)2D3; and 3) a 3- to 15-fold increase in the 1,25-(OH)2D3 concentration required to elicit half-maximal induction of [3H]25-hydroxyvitamin D3-24-hydroxylating activity (ED50; rank order Sanguinus much greater than Pithecia greater than Alouatta). Although the internalization capacity of cells from two different primates in the genus Aotus was 3- to 4-fold lower than that in catarrhine cells, the internalization constant for hormone and ED50 for 24-hydroxylating activity were similar. These data suggest that the functional 1,25-(OH)2D3-receptor phenotype of the owl monkey, Aotus trivirgatus, is more closely aligned to the catarrhine phenotype than are those of other platyrrhines in the families Cebidae and Callitricidae.

Alouatta↗
PubMed1989

Differences in mineral metabolism among nonhuman primates receiving diets with only vitamin D3 or only vitamin D2.

We tested for differences in aspects of mineral metabolism during the administration of diets with only vitamin D3 or only vitamin D2 in four nonhuman anthropoid primate species [two catarrhini, Macaca fascicularis (crab-eating macaque) and Macaca mulatta (rhesus macaque), and two platyrrhini, Saimiri sciureus (squirrel monkey) and Aotus vociferans (night monkey)]. All four species maintained approximately 2- to 3-fold higher serum 25-hydroxyvitamin D (25OHD) level while receiving vitamin D3 than while receiving similar amounts of vitamin D2. Serum 25OHD in M. mulatta receiving the standard primate dietary supplement of vitamin D3 was high enough (360 +/- 60 vs. 70 +/- 25 nM in vitamin D-supplemented humans; P less than 0.0001) to suggest that this widely used level of vitamin D3 supplementation is excessive for some M. mulatta. Serum 24,25-dihydroxyvitamin D [24,25-(OH)2D] in A. vociferans was uniquely high [P less than 0.01; species mean, 19 +/- 5, 95 +/- 12, and 27 +/- 5 nM in groups receiving diets with 1.5 IU vitamin D3/g, 6.6 IU vitamin D3/g, and 15 IU vitamin D2/g, respectively; mean 24,25-(OH)2D from the other three species pooled across three diets was 7 +/- 5 nM]. We confirmed relative resistance to 1,25-(OH)2D in S. sciureus, manifested by osteomalacia and moderately high serum 1,25-(OH)2D. Serum 1,25-(OH)2D in S. sciureus increased 4-fold (P less than 0.05) when the precursor in serum was changed from 250HD3 to 250HD2, suggesting that this species shows more severe resistance to 1,25-(OH)2D2 than to 1,25-(OH)2D3. In conclusion, we found many differences in vitamin D metabolism among four nonhuman anthropoid primate species. The striking feature in A. vociferans (high, 24,25-(OH)2D without high 25OHD in serum independent of whether diet contained only vitamin D3 or only vitamin D2) should allow determination of whether 24,25-(OH)2D functions as a unique agonist or an inactive metabolite in this species.

Animals↗
PubMed1990

Highly vectorial secretion of inhibin by primate Sertoli cells in vitro.

Having recently demonstrated highly vectorial and FSH-stimulated inhibin secretion by immature rat Sertoli cells in vitro, we wished to determine if vectorial secretion of inhibin was also characteristic of primate Sertoli cells. By adapting techniques for isolation of Sertoli cells from testes of the immature rat and cynomolgus monkey. Sertoli cells were isolated from immature baboon testes. Sertoli cells were then plated onto matrix-impregnated porous filters and cultured in twin chamber assemblies in fully defined, supplemented HEPES-buffered Eagles medium. Inhibin was measured in conditioned culture media by an heterologous RIA validated for primate inhibins. Throughout 28 days of culture immunoreactive inhibin was readily detectable in the upper chambers whereas inhibin was undetectable or just detectable in the lower chambers. The median ratio of upper to lower chamber inhibin content was 15.3 under basal conditions rising to 41 under FSH stimulation. Inhibin secretion into the upper chamber was increased 2.5 +/- 0.4 times by stimulation with ovine FSH (100 ng/ml). We conclude that immature Sertoli cells from a nonhuman primate demonstrate FSH-responsive and highly vectorial secretion of inhibin almost exclusively into the upper chamber. These data suggest that during maturation mammalian Sertoli cells secrete inhibin vectorially mainly from the apical surface of the cell towards the seminiferous tubular lumen. The predominance of inhibin secretion into the seminiferous tubule during testicular maturation suggests that inhibin may have an important paracrine or autocrine role in the developmental biology of spermiogenesis.

Animals↗
PubMed1990

Different combinations of regulatory elements may account for expression of the glycoprotein hormone alpha-subunit gene in primate and horse placenta.

Expression of the glycoprotein hormone alpha-subunit gene occurs in the pituitaries of all mammals and in the placentas of primates and horses. In humans, tandem cAMP response elements (CREs), located in the proximal promoter-regulatory region of the alpha-subunit gene, act together with an adjacent upstream regulatory element to confer placenta-specific expression. Here, we report that the alpha-subunit genes of Old World Monkeys contain a single functional CRE. This suggests that tandem CREs are unique to higher primates and humans and are not absolutely required for placenta-specific expression. In contrast, the comparable promoter-regulatory region of the horse alpha-subunit gene lacks a functional CRE but appears to retain a functional upstream regulatory element. This suggests that acquisition of placenta-specific expression of the alpha-subunit gene occurred independently in these distantly related mammals. As a result, different combinations of cis-acting elements may explain why expression of the alpha-subunit gene only occurs in placenta of primates and horses.

Animals↗
PubMed2004

Development of primitive and definitive hematopoiesis from nonhuman primate embryonic stem cells in vitro.

Although information about the development of primitive and definitive hematopoiesis has been elucidated in murine embryos and embryonic stem (ES) cells, there have been few in vitro studies of these processes in primates. In this study, we investigated hematopoietic differentiation from cynomolgus monkey ES cells grown on OP9, a stromal cell line deficient in macrophage colony-stimulating factor. Primitive erythrocytes (EryP) and definitive erythrocytes (EryD) developed sequentially from ES cells in the culture system; this was confirmed by immunostaining and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of embryonic, fetal and adult globin genes. EryP were detected on day 8 without exogenous erythropoietin (EPO), whereas EryD appeared on day 16 and had an indispensable requirement for exogenous EPO. RT-PCR analysis of the cultures revealed a sequential expression of genes associated with primitive and definitive hematopoietic development that was equivalent to that seen during primate ontogeny in vivo. Vascular endothelial growth factor (VEGF) increased, in a dose-dependent manner, not only the number of floating hematopoietic cells, but also the number of adherent hematopoietic cell clusters containing CD34-positive immature progenitors. In colony assays, exogenous VEGF also had a dose-dependent stimulatory effect on the generation of primitive erythroid colonies. More efficient primitive and definitive erythropoiesis was induced by re-plating sorted CD34-positive cells. Thus, this system reproduces early hematopoietic development in vitro and can serve as a model for analyzing the mechanisms of hematopoietic development in primates.

Animals↗
PubMed2006

Cutting corners: the dynamics of turning behaviors in two primate species.

In an attempt to characterize more fully the variation in substrate reaction forces in the locomotor repertoire of primates, we recorded the forces involved in directional changes for two species. These are the first records of turning forces for vertebrate quadrupeds, much less primates. Three ring-tailed lemurs and two patas monkeys performed turns of approximately 30 degrees as they crossed a force platform. The ring-tailed lemurs also turned on a horizontal branch-like support with a segment attached to the force transducer. Mediolateral forces of up to 40% body weight were recorded. These are considerably higher than during linear locomotion. Pivot limbs in ground turns and turns on the branch differed in the lemurs, suggesting that substrate influences turning strategies. Limbs encountered both medial and lateral reaction forces, and as a result, they may be exposed to variable bending regimes in the frontal plane. The stereotypy in bending regimes suggested by in vivo bone strain studies, therefore, may characterize linear locomotion only. The lemurs showed hindlimb dominance in turns, both in terms of frequency used as well as force magnitude (hindlimb steering). Hindlimb dominance in weight support characterizes both species (and primates in general), but it is more pronounced in the lemurs. In the patas monkeys, forces were more evenly distributed among the two pairs of limbs. The mediolateral turning forces therefore seem to track the amount of weight to be shifted sideways. Overall variance in mediolateral forces was greater in the arboreal and versatile lemurs than in the terrestrial and cursorial patas monkeys.

Animals↗