Search PubMed⌕ Search

Biomedical subjects

F Naftolin

Publications and source records attributed to F Naftolin.

At least 181 records · Page 10Linked to original sources
PubMed1988

Neuronal membrane remodelling during the oestrus cycle: a freeze-fracture study in the arcuate nucleus of the rat hypothalamus.

Freeze-fracture methodology was used to study the organization of the neuronal plasma membrane in the rat arcuate nucleus, an oestrogen sensitive area of the hypothalamus. The quantitative evaluation of freeze-fracture replicas of the perikarya, dendritic shafts and dendritic spines revealed that the numerical density of intramembranous particles varied during the ovarian cycle. The number of small (less than 10 nm) particles was decreased, and the number of large (greater than 10 nm) particles was increased, in the P-face of the perikaryal plasma membranes in prooestrus and oestrus when compared to dioestrus. This change was associated with a significant increase in the number of exo-endocytotic images in the perikaryal plasma membrane in prooestrus. Changes in intramembranous particles during the ovarian cycle were not detected in arcuate nucleus dendritic shafts and dendritic spines.

Animals↗
PubMed1988

Follicular development is impaired by inhibitors of serine proteases in the rat.

Serine proteases such as plasminogen activators are produced by granulosa cells both in vivo and in vitro and have been implicated in the process of ovulation. For a study of potential roles of serine proteases in early follicular development, immature rats were injected with pregnant mare serum gonadotropin, followed 2 hours later by laparotomy and injection of the serine protease inhibitors benzamidine and epsilon-aminocaproic acid into the bursa of one ovary. As a control, saline solution was injected into the contralateral bursa. Animals were put to death 48 hours after injection of serine protease inhibitors, and three to five randomly selected longitudinal sections were evaluated by computerized morphometry. The area occupied by antral follicles relative to the total cross-sectional area of each section was computed. Resultant ratios from serine protease inhibitor-treated ovaries were compared with those from contralateral control ovaries. Ninety-three percent of serine protease inhibitor-treated ovaries showed a reduction in antral follicular size when compared with corresponding control ovaries, which is indicative of inhibitory effects of serine protease inhibitor treatment on folliculogenesis. To further investigate this effect, ovulation was induced by human chorionic gonadotropin administration 48 hours after pregnant mare serum gonadotropin and 46 hours after serine protease inhibitor or saline solution treatment. Animals were put to death 20 hours later and the number of oocytes ovulated into oviducts was determined. Oviducts from serine protease inhibitor-treated ovaries contained 51% fewer oocytes than their control counterparts. Artifacts of surgical stress or vascular diffusion of serine protease inhibitor from treated to control sides were ruled out by appropriate control experiments. We conclude that early serine protease inhibitor treatment of pregnant mare serum gonadotropin-stimulated rat ovaries impairs folliculogenesis. Thus, in addition to involvement in ovulation, serine proteases appear to play important roles throughout follicular development.

Aminocaproic Acid↗
PubMed1988

Prognostic significance of the human yolk sac assessed by ultrasonography.

Ultrasonographic examinations were conducted between 6 and 12 weeks' gestation in 77 first-trimester pregnancies with normal fetal outcome. Each examination consisted of measurements of the secondary yolk sac diameter and the fetal crown-rump length. The yolk sac was seen in all cases, and whereas its measurements demonstrated wide biologic variability, it correlated weakly (R2 = 0.39) with gestational age as confirmed by crown-rump length measurements. Growth of the yolk sac diameter, although slight, assumed a curvilinear relationship with gestational age. Such a growth profile is best described by a second-degree polynomial regression equation. The yolk sac performs important functions for embryonic development during organogenesis and the remnant of the secondary yolk sac seen on ultrasonography is often considered to be a potential predictor of fetal outcome. Our findings indicate that the size of this remnant in pregnancies with normal karyotypes and normal fetal outcomes is extremely variable. Additionally, the yolk sac size in patients with karyotypic abnormalities and spontaneous abortion were equally variable and almost all were within the normal range. In light of these findings, the secondary yolk sac size does not appear to be a sensitive predictor of embryonic integrity and pregnancy outcome.

Female↗
PubMed1988

Fatty acid content of yolk sac and embryo in hyperglycemia-induced embryopathy and effect of arachidonic acid supplementation.

Using the postimplantation rat conceptus model, we analyzed with gas-liquid chromatography, the fatty acid composition in major lipid groups (phospholipids, triglycerides, nonesterified fatty acids, and cholesterol esters) of yolk sacs and embryos cultured for 48 hours under control, hyperglycemic, and arachidonic acid-supplemented hyperglycemic conditions. In all experimental conditions the yolk sacs had greater fatty acid content than the embryos in all lipid groups except in nonesterified fatty acids. The fatty acid level in embryonic nonesterified fatty acids was significantly higher (p less than 0.05) in hyperglycemia-exposed embryos than found with arachidonic acid supplementation. Total yolk sac triglycerides were greater with added glucose (p less than 0.05) than with the addition of arachidonic acid to the same medium. Oleic acid, a fatty acid associated with essential fatty acid deficiency, was increased in the embryonic phospholipids and nonesterified fatty acids of conceptuses exposed to excess glucose, as well as in the culture media of this group, compared with the control or arachidonic acid-supplemented, hyperglycemic group (p less than 0.05). The results of this study demonstrate that diabetes-related embryopathy is associated with quantitative and qualitative abnormalities in major lipid groups. Furthermore, the elevation in embryonic oleic acid level suggests that the teratogenic mechanism could be related to a deficiency in essential fatty acids. The pattern of essential fatty acid deficiency and embryopathy was preventable with arachidonic acid supplementation in this experimental model.

Animals↗
PubMed1988

Estrogen hydroxylase activity in the human placenta at term.

Placental estrogen hydroxylase (EH) enzyme activity was measured at term using the catechol-O-methyl transferase coupled method in normal and high risk conditions. The identity and ratio of products formed during incubation of microsomes as analysed by high performance liquid chromatography in chronic hypertension, toxemia and diabetes mellitus was not different from controls. The mean enzymatic activity was also not different among the conditions studied as expressed mean +/- SE pmol/min/mg, protein: chronic hypertension (7.8 +/- 1), toxemia (8 +/- 1.6), diabetes mellitus (6.1 +/- 0.9) and controls (8.3 +/- 1.5). The cofactor dependence of EH was studied showing that NADPH is a better substrate for the enzyme than NADH.

Catechol O-Methyltransferase↗
PubMed1988

The cellular effects of estrogens on neuroendocrine tissues.

Estrogen action on sensitive neurons in the rat diencephalon has been studied by morphologic techniques; evidence of estrogen action at every level is presented, including tracts, cells, circuitry and subcellular organelles. The demonstration in the arcuate nucleus of estrogen-induced synaptic remodelling, estrogen-induced postsynaptic membrane phenotypes, changes in intracellular membranes and rapid estrogen actions on neuronal endo-exocytosis indicates that cellular estrogen actions may underlie the neuronal control of reproduction.

Animals↗
PubMed1988

Immunocytochemical localization of angiotensin II immunoreactivity and demonstration of angiotensin II binding in the rat ovary.

The cellular localization of angiotensin II immunoreactivity and the presence of angiotensin II binding in rat ovaries were studied. Angiotensin II immunohistochemical staining was demonstrated throughout the corpora lutea of gonadotropin-stimulated immature rats and pseudopregnant adult rats, as well as in some stromal and thecal cells surrounding large antral follicles. No immunostaining was observed in granulosa cells of preantral or antral rat follicles or in ovaries from unstimulated immature rats. With in vitro autoradiography, specific, saralasin-suppressible 125I-angiotensin II binding was demonstrated in normal cycling rat ovaries: diestrus greater than proestrus greater than estrus. The combined findings of angiotensin II immunostaining in ovarian follicles and corpora lutea and of cycle-related angiotensin II binding support the hypothesis of a functional role for the ovarian renin-angiotensin system.

Angiotensin II↗
PubMed1988

Catechol-o-methyl transferase activity in the human term placenta.

Catechol-O-methyltransferase (COMT) characteristics and activity were studied using radioenzymatic techniques in placentas from normal and high-risk patients at term. The affinity of the catechol estrogen 20-hydroxyestrone (2OHE1), Km = 5 microM, for the enzyme was found to be at least 90-fold higher than that of the catecholamines norepinephrine, epinephrine, and dopamine (450, 490, and 850 microM, respectively). The product formed after incubation of placental cytosol with tritiated 20HE1 was identified as being exclusively (3H) 2-methoxyestrone, by use of high-performance liquid chromatography. Placental COMT activity after normal spontaneous delivery was no different from that obtained after elective cesarean section (270 +/- 20 versus 275 +/- 27, expressed as mean +/- SE activity nanomoles of 2-methoxyestrone formed per hour/mg protein). Placental COMT activity at term in women with hypertension (toxemia [T] or chronic hypertension [CHBP]) was significantly lower than in control subjects (284 +/- 27 versus 183 +/- 26; P less than 0.05). No significant differences in enzyme activity were found between T and CHBP (175 +/- 37 versus 210 +/- 32, P = NS). There were also no differences in COMT activity of diabetic classes A-R (White classification), fetal distress (with or without acidosis), and controls. The possible interference of antihypertensive drugs used by the patients in the study on COMT activity was assessed. Incubations of healthy placental cytosol with hydralazine, methyldopa, and Mg++ in their estimated plasma therapeutic concentrations had no effect on placental COMT activity. The present study suggests that placental COMT activity is low in patients with hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Antihypertensive Agents↗
PubMed1988

Clinical significance of liver dysfunction in pregnancy-induced hypertension.

Hepatic dysfunction is one of the frequent manifestations of multisystemic involvement in preeclampsia. This study was conducted to establish the impact of liver dysfunction on maternal and neonatal outcome in women with pregnancy-induced hypertension (PIH). The prevalence of liver dysfunction as determined by an elevated serum glutamic oxalacetic transaminase (SGOT) concentration was 21% in a population of 355 patients with PIH. Liver dysfunction was associated with the presence of severe hypertension, proteinuria, a lower platelet count, and renal compromise (elevated blood urea nitrogen, creatinine, and uric acid serum concentrations). Abdominal pain was also associated with an SGOT elevation. Liver dysfunction was associated with intrauterine growth retardation and prematurity. Furthermore, the association with these neonatal complications was independent from the severity of the hypertension and the presence of proteinuria. Thus, we conclude that liver dysfunction is a frequent complication of PIH and that it is an independent risk factor for maternal and perinatal complications.

Aspartate Aminotransferases↗
PubMed1988

Catecholaminergic innervation of luteinizing hormone-releasing hormone and glutamic acid decarboxylase immunopositive neurons in the rat medial preoptic area. An electron-microscopic double immunostaining and degeneration study.

Catecholaminergic innervation of luteinizing hormone-releasing hormone (LHRH) and glutamic acid decarboxylase (GAD) immunoreactive neurons in the rat medial preoptic area (MPO) was studied using electron-microscopic (EM) double-label immunostaining and combinations of single- and double-label immunostaining with acute axonal degeneration. The EM double-immunostaining experiments included double staining for either tyrosine hydroxylase (TH) and LHRH, or TH and GAD. Analysis of TH and LHRH double-immunostained material revealed synaptic connections between TH immunoreactive axons and LHRH immunopositive neurons. The TH and GAD double-staining experiments also demonstrated synaptic connections between axons immunoreactive for TH and GAD immunopositive neurons. Two days following unilateral surgical transection of the ventral and dorsal noradrenergic bundles, synaptic connections were found between degenerated boutons and GAD immunoreactive neurons in the ipsilateral MPO. However, no synapses could be observed in the same area between degenerated axons and the LHRH immunopositive neurons. Following the same operation and immunostaining for TH, a moderate number of degenerating TH axons as well as a large number of nondegenerated TH immunoreactive boutons were observed. Double immunostaining for TH and GAD in MPO sections ipsilateral to the operation revealed synaptic connections between the degenerating TH immunopositive axons and GAD immunoreactive neurons. These results suggest that there are direct synaptic connections between catecholaminergic axons and GAD and LHRH immunoreactive neurons in the medial preoptic area of the rat. Some of the connections between TH immunopositive afferents and GAD immunoreactive neurons may represent connections from noradrenergic neurons in the brain stem, while the majority of TH-GAD and TH-LHRH connections may represent innervation of GABA and LHRH neurons from local dopamine-containing cells.

Adrenergic Fibers↗
PubMed1988

Poissons, grenouilles, femmes et hommes: the appropriation and retention of archetypal systems for reproduction.

In contradistinction to other biological systems, the reproductive mechanisms in sexually reproducing species are unique in that their success relies upon a synchronous interaction between two separate individuals. Reproduction has become increasingly more efficient as higher forms have developed internal fertilization and gestation. Although our anthropomorphic perspective has dominated the understanding of reproductive processes, 'recent discoveries' make it clear that this reproductive efficiency has been gained by retention of previously present biological mechanisms whose origins are in the vestigial excretory tracts and ducts which are the precursors of the reproductive tract. We refer to these as 'archetypal systems'. They include the interaction between sex steroid sensitive tissues and sex steroids, the renin-angiotensin system and the macrophage/monokine response to infection. Through these mechanisms the reproductive tracts have maintained control over the microenvironment in which the reproductive processes occur. Thus, gamete development in male and female, and fertilization and early embryonic existence in the female tract prior to implantation still occur in compartments which are extracorporeal, i.e., separated from blood or subendothelial spaces, and are controlled by cellular mechanisms found in ancient excretory tracts. Since the majority of the changes between lower forms and contemporary mammals are anatomical modifications which have favoured the success of these extracorporeal events within the developing, generally land-based mammals, we should take special note of lower animals, understanding the evolutionary appropriation of mechanisms designed to furnish the suitable microenvironment from the surrounding tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Estrogen-induced synaptic remodelling in adult rat brain is accompanied by the reorganization of neuronal membranes.

Adult cycling female rats were injected with estradiol valerate (2 mg/100 g body wt.), a treatment which has previously been shown to result in synaptic remodelling in the arcuate nucleus and constant vaginal estrus. During the 32 weeks following estrogen treatment, arcuate nucleus neuronal plasma membranes were quantitatively assessed for intramembrane particle (IMP) number and size using freeze-fracture techniques. Neuronal membranes from untreated cycling females, females injected with oil and untreated males were also studied. Untreated rats had dimorphic sexual phenotypes in membrane organization; female rats had more IMP than males, mainly due to greater numbers of small (less than 10 nm) particles. These sex differences were observed in perikarya and dendritic shafts, but not in dendritic spines. Following estrogen treatment the density of IMP in membranes from females decreased. The IMP changes were found only in neuronal perikarya and dendritic shafts, not in dendritic spines, and were mainly due to a massive decrease in the number of small (less than 10 nm) IMP which was only partially offset by an increase in the number of large (greater than or equal to 10 nm) IMP. Thus, by 32 weeks after estradiol valerate treatment, the number and size of IMP in neuronal membranes from females were not different from those seen in normal males. These results strengthen the idea that estradiol may affect the turnover of certain neuronal membrane components in sex-steroid sensitive areas of the brain.

Animals↗
PubMed1987

Metabolism and binding of androgens in the spinal cord of the rat.

The binding of [3H]androgens and estrogens, and the metabolism of [3H]androgens, were studied in the spinal cord of the adult rat. High-affinity, specific binding sites for [3H]testosterone and [3H]estradiol were detected in cytosol fractions from the spinal cords of castrate animals. Equilibrium dissociation constants for reaction of these sites with their respective ligands were similar to those of androgen and estrogen receptors from other regions of the central nervous system. Nuclear binding of [3H]estradiol was observed in the spinal cord 1 h after intravenous administration of the isotope. Likewise, exchange assay demonstrated the presence of high-affinity androgen binding sites in spinal cord nuclei from orchidectomized, testosterone propionate treated animals. 5 alpha-Reductase activity in homogenates of the spinal cord was relatively high, approximately 3 times that in the pooled hypothalamus, preoptic area, septum and amygdala. However, in contrast to the latter brain regions, estrogen formation was not detectable in spinal cord tissue. No sex differences were observed in the metabolism of [3H]testosterone by spinal cord homogenates. These results confirm the presence of androgen and estrogen receptors in the rat spinal cord. The lack of detectable aromatase activity in the spinal cord is consistent with the hypothesis that the effects of circulating testosterone on spinal reflex function are mediated primarily through the androgen receptor system.

Androgens↗
PubMed1987

Xenopus oocytes injected with rat uterine RNA express very slowly activating potassium currents.

Under the influence of estrogen, uterine smooth muscle becomes highly excitable, generating spontaneous and prolonged bursts of action potentials. In a study of the mechanisms by which this transition in excitability occurs, polyadenylated RNA from the uteri of estrogen-treated rats was injected into Xenopus oocytes. The injected oocytes expressed a novel voltage-dependent potassium current. This current was not observed in oocytes injected with RNA from several other excitable tissues, including rat brain and uterine smooth muscle from ovariectomized rats not treated with estrogen. The activation of this current on depolarization was exceptionally slow, particularly for depolarizations from relatively negative membrane potentials. Such a slowly activating channel may play an important role in the slow, repetitive bursts of action potentials in the myometrium.

Animals↗
PubMed1987

Intraovarian markers of follicular and oocyte maturation.

The use of ovulation induction for multiple follicular growth in in vitro fertilization (IVF) has introduced the problem of follicular asynchrony. As a consequence of the asynchrony, the parameters most commonly used by IVF groups to assess follicular and oocyte quality within those follicles are not sufficiently sensitive or specific. Thus, each follicle must be considered separately, and specific markers of follicular and/or oocyte maturation must be sought from within the follicle. In this review we analyze previous reports of potential markers of follicular and oocyte maturation. In regards to the follicular fluid constituents, the level of estradiol in follicular fluid correlates with fertilization and pregnancy in stimulated cycles. Other steroids are only helpful when specific stimulation protocols are used. The level of some follicular proteins such as alpha-1-antitrypsin and fibrinogen also correlates with fertilization and pregnancy outcome. Cyclic AMP levels in follicular fluid are significantly reduced in follicles leading to conception. Regulators of oocyte maturation, such as the Oocyte Maturation Inhibitor (OMI) or the Meiosis Inducing Substance (MIS) have also been correlated with IVF outcome, but their exact structure remains still unknown. In addition, other sophisticated parameters, such as chemotactic activity of human leukocytes, or simple methods, such as the presence of intrafollicular echoes, have also been used as successful markers in predicting IVF outcome.

Animals↗
PubMed1987

Nuclear pores in rat hypothalamic arcuate neurons: sex differences and changes during the oestrous cycle.

The numerical density of nuclear pores was assessed on freeze-fracture replicas of hypothalamic arcuate neurons from adult male and female rats. In females the nuclear pore density fluctuated during the oestrous cycle and was higher in oestrus than in pro-oestrus, metoestrus and dioestrus. Nuclear pore density in males and in metoestrus and dioestrus females was similar. The nuclear pore density in male rats was significantly less than that in oestrus and pro-oestrus females. The variation of the number of pores per unit nuclear volume and the total number of pores per nucleus was similar to the variation of the numerical density of nuclear pores. These results provide morphological evidence of cyclic changes in neuronal nucleocytoplasmic traffic during the ovarian cycle.

Animals↗