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At least 1,009 records · Page 56Linked to original sources
PubMed1982

Specificity of the beta 2-adrenergic receptor stimulating cyclic AMP accumulation in the intermediate lobe of rat pituitary gland.

Changes of cyclic AMP levels were used to assess the specificity of the beta-adrenergic receptor in primary cultures of cells prepared from the intermediate lobe of rat pituitary gland. During a 4 min incubation, beta-adrenergic agonists led to a 4 to 6 fold stimulation of cyclic AMP concentration with the following order of potency (Kd values): zinterol (0.75 nM) greater than hydroxybenzylisoproterenol (1.0 nM) greater than (--)-isoproterenol (4.6 nM) greater than soterenol greater than (7.7 nM) greater than (--)-epinephrine (10 nM) greater than OPC 2009 (procaterol, 11 nM) much greater than (--)-norepinephrine (300 nM). The potent antagonists cyanopindolol, (--)-propranolol and hydroxybenzylpindolol reversed the stimulatory effect of (--)-isoproterenol at Kd values of 0.4-0.6 nM. Other beta-adrenergic antagonists had the following order of potency: pindolol = (--)-alprenolol = timolol (0.9-1.0 mM) much greater than metoprolol (100 nM) greater than dichloroisoproterenol (300 nM) greater than butoxamine (1100 nM). The beta 1-selective antagonist practolol had a low potency at 700 nM. The stereoselectivity of the receptor is indicated by the 400 to 70 fold higher potency of the (--)-isomers of isoproterenol, epinephrine and propranolol as compared to their (+)-stereoisomers. The data show that the beta-adrenergic receptor in the intermediate lobe of the rat pituitary gland is mainly of the bet 2-subtype. Study of this pure population of postsynaptic beta-adrenergic receptors where binding could be correlated with other parameters of cellular activity (cyclic AMP formation and alpha-MSH secretion) should yield useful information about the less accessible adrenergic systems of the brain.

Animals↗
PubMed1988

Distribution of Crooke's cells and ACTH cells in the human pituitary glands.

Distribution of ACTH cells and Crooke's cells in the human pituitary glands was studied in 5 autopsy cases. ACTH cells were distributed throughout the anterior pituitary lobes, in particular densely in their anterior halves. Some ACTH cells were found in the posterior pituitary lobes in three cases. Crooke's cells were distributed limitedly in the anterior halves of anterior pituitary in two cases. In the remaining three cases, Crooke's cells were widely distributed in the anterior pituitary lobes but predominantly in their anterior halves. No Crooke's cells were found in the posterior pituitary. These findings suggest that cells in the anterior part of anterior pituitary are more likely to show Crooke's hyaline change than those in the other parts.

Adrenocorticotropic Hormone↗
PubMed1992

The effect of morphine tolerance dependence and abstinence on immunoreactive dynorphin (1-13) levels in discrete brain regions, spinal cord, pituitary gland and peripheral tissues of the rat.

The effect of morphine tolerance dependence and protracted abstinence on the levels of dynorphin (1-13) in discrete brain regions, spinal cord, pituitary gland and peripheral tissues was determined in male Sprague-Dawley rats. Of all the tissues examined, the highest level of dynorphin (1-13) was found to be in the pituitary gland. Among the brain regions and spinal cord examined, the levels of dynorphin (1-13) in descending order were: hypothalamus, spinal cord, midbrain, pons and medulla, hippocampus, cortex, amygdala and striatum. The descending order for the levels of dynorphin (1-13) in peripheral tissues was: adrenals, heart and kidneys. In morphine tolerant rats, the levels of dynorphin (1-13) increased in amygdala but were decreased in pons and medulla. In morphine abstinent rats, the levels of dynorphin (1-13) were increased in amygdala, hypothalamus and hippocampus. The levels of dynorphin (1-13) were increased in pituitary but decreased in spinal cord and remained so even during protracted abstinence. The levels of dynorphin (1-13) in the peripheral tissues of morphine tolerant rats were unaffected. However, in the heart and kidneys of morphine abstinent rats, the levels of dynorphin (1-13) were increased significantly. It is concluded that both morphine tolerance and abstinence modify the levels of dynorphin (1-13) in pituitary, central and peripheral tissues. Morphine abstinence differed from non-abstinence process in that there were additional changes (increases) in the levels of dynorphin (1-13) in brain regions (hypothalamus and hippocampus) and peripheral tissues (heart and kidneys) and may contribute to the symptoms of the morphine abstinence syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Glands↗
PubMed1981

[Vasopressin and "CRF" in the regulation of ACTH secretion by the anterior and intermediate lobes of the pituitary gland (author's transl)].

The aim of this review was to summarize the present state of knowledge concerning the mode of action of vasopressin (VP) and the putative corticotropin releasing factor (CRF) on ACTH secretion from the anterior and intermediate lobes of the pituitary gland. In vitro data show that although both CRF and VP enhanced release of anterior pituitary ACTH, the pattern of hormonal release, based on kinetical and dose-dependent studies, appeared to be different. Also, the effect of VP most probably was mediated by specific putative receptor sites. In contrast, VP was found not to alter ACTH secretion from the intermediate lobe; that secretion seems to be regulated by CRF-like material and neurotransmitters. The importance of VP as a corticotropin agent is discussed.

Adrenocorticotropic Hormone↗
PubMed2005

The pituitary gland: changes on MR images during the 1st year after delivery.

PURPOSE: To longitudinally and prospectively investigate changes in the volume and signal intensity on T1-weighted magnetic resonance (MR) images of the pituitary gland up to 1 year after delivery and evaluate whether termination of lactation has an effect on these parameters. MATERIALS AND METHODS: All participants provided informed consent for participation in the study, which was approved by the institutional review board. Thirteen volunteers (mean age, 28 years; age range, 26-32 years) underwent MR imaging 2 and 4 weeks after delivery and then at intervals of 0.5-2.0 months until 1 year after delivery. Eight participants terminated lactation during the study period. Sagittal and coronal T1-weighted images were obtained. Signal intensities of the anterior and posterior lobes of the pituitary were calculated relative to that of the pons. The volume of the pituitary was also calculated. Two-tailed paired Student t tests and separate simple linear regression analyses were used to test for statistically significant differences. RESULTS: The mean pituitary volume was 544 mm3 at 2 weeks, 523 mm3 at 4 months, 512 mm3 at 8 months, and 511 mm3 at 12 months after delivery, with significant differences between 2 weeks and 4 months (P = .002) and between 4 and 8 months (P = .003) after delivery. The mean ratio of the signal intensity of the anterior lobe of the pituitary to the signal intensity of the pons was 1.11 at 2 weeks, 1.07 at 4 months, 1.03 at 8 months, and 1.00 at 12 months after delivery, with significant differences between 2 weeks and 4 months (P = .004) and between 4 and 8 months (P = .0001) after delivery. Termination of lactation had no statistically significant effect on pituitary volume or the ratio of the signal intensity of the anterior or posterior lobe of the pituitary to the signal intensity of the pons. CONCLUSION: The volume of the pituitary gland decreases up to 8 months after delivery, and the T1-weighted signal intensity of the anterior lobe of the pituitary decreases; termination of lactation has no statistically significant effect on these parameters.

Adult↗
PubMed1997

MR height of the pituitary gland as a function of age and sex: especially physiological hypertrophy in adolescence and in climacterium.

PURPOSE: To clarify the age- and sex-related changes in pituitary height. METHODS: We reviewed sagittal T1-weighted MR images in 1020 subjects to analyze the size of the pituitary gland. RESULTS: The pituitary height in female subjects (mean, 5.35 mm; SD, 1.2) was significantly greater than that in male subjects (mean, 4.93 mm; SD, 1.0). When the data were analyzed for different age ranges, sex-related differences were statistically significant only in the 10- to 19-, 20- to 29-, and 50- to 59-year-old age groups. The pituitary height peaked in the 20-to-29 age group and tended to decline with age. In female subjects, however, there was a tendency for pituitary height to increase again in the 50-to-59 age group. CONCLUSION: The pituitary height may reflect physiological neuroendocrine differences between younger and older subjects and between male and female subjects. The second increase observed in female subjects may likewise reflect high concentrations of gonadotropic hormones, apparently due to an age-related decline in circulating gonadal steroids and an increase in gonadotropin-releasing hormone.

Adolescent↗
PubMed2004

Food restriction regulates adipose-specific cytokines in pituitary gland but not in hypothalamus.

White adipose tissue is now recognized as the source of a growing list of novel adipocyte-specific factors, or adipokines. These factors regulate energy homeostasis, including the response to food deprivation. We hypothesized that the brain and pituitary gland would also express adipokines and their regulatory factors and subsequently demonstrated that the rodent brain-pituitary system expresses mRNA and protein for leptin and resistin. We now report that the adipokines FIAF and adiponutrin, as well as the nuclear hormone receptor PPAR gamma, are expressed in pituitary, brain and adipose tissue. In pituitary gland, 24 h of food restriction reduced PPAR gamma expression by 54% whereas both adiponutrin and FIAF were increased 1.7 and 2.3 fold, respectively. These changes in expression were similar to those observed in fat, except for adiponutrin, which by contrast is dramatically reduced 95% by fasting. Furthermore, whereas PPAR gamma 2 is the main isoform affected by fasting in adipose tissue, our data suggest that only PPAR gamma 1 is present and downregulated by fasting in pituitary tissue. In contrast to the sensitivity of pituitary tissue to the effects of fasting, no significant change in expression was observed in basal hypothalamus for any of the genes studied. Overall, our data suggest that pituitary-derived adipokines may play an unexpected role in the neuroendocrine regulation of energy homeostasis.

Adipose Tissue↗
PubMed1976

Hypothalamus and cytodifferentiation of the foetal pituitary gland. Study in vivo.

To investigate whether the hypothalamus is involved in the cytodifferentiation of the anterior pituitary gland, rat foetuses were encephalectomized in utero on day 16 of pregnancy. Pituitary sections from encephalectomized and normal littermate foetuses were studied on day 21 with the immunofluorescence technique using antibodies anti alpha-MSH, anti beta-MSH, anti alpha-(17-39) ACTH and anti beta-(1-24) ACTH. On day 16, only the anti beta-MSH revealed a few cells in the pars distalis but not in the pars intermedia. On the other hand, on day 21, the pituitary cells reacting with antibodies anti alpha-MSH, anti beta-MSH and anti alpha-(17-39) ACTH were as numerous in the encephalectomized foetuses as in the normal littermate foetuses. The cells revealed with the antibody anti beta-(1-24) ACTH were less numerous and less fluorescent in the pars distalis and intermedia of the hypophysis of the encephalectomized foetuses. On day 21, the adrenals of the encephalectomized foetuses were atrophied in comparison with those of the normal littermate foetuses but they were larger than on day 16. These data suggest that the cytodifferentiation of the corticotroph and melanotroph cells of the hypophysis occurs without the influence of the hypothalamus which is necessary for the normal release of ACTH.

Adrenal Glands↗
PubMed2003

Molecular cloning and functional characterization of a vasotocin receptor subtype expressed in the pituitary gland of the domestic chicken (Gallus domesticus): avian homolog of the mammalian V1b-vasopressin receptor.

The neurohypophysial hormone arginine vasotocin (AVT) stimulates adrenocorticotropin hormone (ACTH) secretion from the avian anterior pituitary gland resulting in increased adrenal secretion of corticosterone in response to stress. Here, we report molecular cloning and functional characterization of a gene encoding an AVT receptor subtype, designated the VT2 receptor, that may mediate the stimulatory effect of AVT on ACTH secretion in birds. The open reading frame predicts a 425 amino acid polypeptide that includes seven segments of 19 to 24 hydrophobic amino acids, typical of guanine nucleotide-protein coupled receptors. Phylogenetic analysis revealed that the VT2 receptor shares highest identity with the mammalian V1b-vasopressin receptor subtype. Expressed VT2 receptors in COS7 cells mediate AVT-induced phosphatidylinositol turnover and Ca(2+) mobilization. In the domestic chicken, expression of VT2 receptor gene transcripts is limited to the pituitary gland. Based on similarities in sequence, site of expression and coupled signal transduction pathways, we conclude that the VT2 receptor is the avian homolog of the mammalian V1b-vasopressin receptor, and therefore may play an important role in the avian stress response.

Amino Acid Sequence↗
PubMed1997

Immunocytochemical localization of prohormone convertases PC1 and PC2 in the anuran pituitary gland: subcellular localization in corticotrope and melanotrope cells.

Specific antisera against mammalian prohormone convertases PC1 and PC2 have been used to examine, light-immunocytochemically, the distribution of these enzymes in the pituitary gland of five different species of anuran amphibians (Rana catesbeiana, Bufo japonicus formosus, Xenopus laevis, Rana brevipoda porosa, and Buergeria japonica). A differential pattern of immunoreactivity of PC1 and PC2 was found among these species. Only PC1 was found in the corticotrope cells of the pars distalis in R. catesbeiana, B. japonicus formosus, and X. laevis. Only PC2 was observed in these cells in B. japonica, whereas both PC1 and PC2 were present in these cells in R. brevipoda porosa. PC2 immunoreactivity was always observed in melanotrope cells in the pars intermedia of all of the species, but it coexisted with PC1 immunoreactivity only in R. catesbeiana and X. laevis. The nerve fibers and terminals in the pars nervosa in all of the species were intensely immunopositive with both PC1 and PC2 antibodies. Immunoelectron microscopy on B. japonicus formosus and B. japonica, by means of double-labeling with gold particles of different sizes, revealed that almost all the adrenocorticotropin-positive secretory granules in the corticotrope cells and alpha-melanophore-stimulating-hormone-positive secretory granules in the melanotrope cells were also labeled with either PC1 or PC2 antibodies. This study suggests that PC1 and PC2 are involved in the intracellular proteolytic cleavage of proopiomelanocortin in amphibian pituitary glands, a situation similar to that proposed for mammals.

Adrenocorticotropic Hormone↗
PubMed1983

[Absence of dopaminergic receptor sites identified with (H3)-spiroperidol in the intermediate lobe of the rabbit pituitary gland].

Dopaminergic receptors were sought in the intermediate lobe of the pituitary gland by measuring specific 3H-spiroperidol binding. This approach enabled the identification of specific sites in the Mouse neurointermediate lobe. In contrast, no such sites seem to exist in the Rabbit intermediate lobe. However, in the latter species, numerous 3H-spiroperidol binding sites were detected in the anterior lobe. These observations tally with immunocytochemical data showing the absence of catecholaminergic innervation from the Rabbit intermediate lobe and explain why dopamine has no effect on alpha MSH release from the perifused gland. A new mode of regulation of melanotrophic function, not based on inhibitory dopaminergic control, must be envisaged in Leporidae.

Animals↗
PubMed2000

Transcription factors in pituitary gland development and their clinical impact on phenotype.

OBJECTIVE: Several genes encoding homeobox transcription factors are important for normal pituitary gland development and eventually for hormone production. METHODS AND RESULTS: By interacting with each other on the basis of a distinct temporal and spatial expression pattern, as well as with other extrinsic and intrinsic signals, they control cell determination, cell differentiation and eventually maintenance of cell function which is most important for the lifelong secretion of the pituitary-derived hormones in an appropriate manner. The different phenotypes, as mainly studied in the mouse, may help to analyze the consequences of disruption of a known or yet unknown individual transcription factor in humans. CONCLUSION: Therefore, to study the different steps in morphogenesis will shed light onto developmental processes which will open a most fascinating time not only for basic scientists and biologists, but also for clinicians seeing all these patients.

Animals↗
PubMed1993

Induction of the gonadotrophin surge-inhibiting factor by FSH and its elimination: a sex difference in the efficacy of the priming effect of gonadotrophin-releasing hormone on the rat pituitary gland.

This study was designed to explore the efficacy of gonadotrophin-releasing hormone (GnRH) to antagonize the effect of gonadotrophin surge-inhibiting factor (GnSIF) on the timing of the induction by GnRH of the maximal self-priming effect on pituitary LH responsiveness. The GnSIF levels were increased by FSH treatment and reduced after gonadectomy. Female rats were injected s.c. with 10 IU FSH or saline (control) on three occasions during the 4-day cycle. Serial i.v. injections of GnRH (500 pmol/kg body weight) were administered to intact rats on the afternoon of pro-oestrus or 15-30 min after ovariectomy. Intact male rats were given 10 IU FSH and 500 or 2000 pmol GnRH/kg body weight on an equivalent time-schedule. Endogenous GnRH release was suppressed with phenobarbital. In intact female control rats, the timing of the maximally primed LH response was delayed as the GnRH pulse-interval increased. FSH treatment of female rats induced a suppression of the initial unprimed LH response and delayed the maximally primed LH response, which showed further delay as the GnRH pulse-interval was increased. When the pulsatile administration of GnRH was started 15-30 min after ovariectomy, the priming effect of GnRH did not change as the GnRH pulse-interval was increased in the saline-treated rats. However, FSH treatment caused a suppression of the unprimed LH response, a delay in the primed LH response and decreased the delay of the maximally primed LH response to GnRH when the GnRH pulse-interval was decreased. Increasing the interval between ovariectomy and the first GnRH pulse to 4 h diminished the efficacy of the FSH treatment: GnRH-induced priming was delayed by only one pulse instead of the two pulses in control rats. In intact males but not in orchidectomized rats, a self-priming effect was demonstrated during GnRH pulses which were 1 h apart. The effect of 2 nmol GnRH/kg body weight was the most pronounced. Compared with intact female rats, the timing of the maximally primed LH response was delayed by 1 h. FSH treatment did not affect the pituitary LH response to both dose levels of GnRH. It is concluded that FSH treatment increased the release of GnSIF by the ovary, then induced a state of low responsiveness of the pituitary gland to GnRH and subsequently delayed GnRH-induced maximal self-priming. The efficacy of GnRH to prime the pituitary gland was higher when GnSIF levels were decreasing after removal of the ovaries.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗