Effects of naloxone,morphine and methionine enkephalin on serum prolactin,luteinizing hormone,follicle stimulating hormone,thyroid stimulating hormone and growth hormone

The response of 5 anterior pituitary hormones to single injections of naloxone, morphine and metenkephalin administration was measured in male rats. Morphine and met-enkephalin significantly increased serum prolactin and GH concentrations, and significantly decreased serum LH and TSH concentrations. Naloxone reduced serum prolactin and GH concentrations, increased serum LH and FSH, but had little effect on serum TSH concentrations. Concurrent injections of naloxone with morphine or met-enkephalin reduced the response to each of the drugs given separtely. These results suggest that endogenous morphinomimetic substances may participate in regulating secretion of anterior pituitary hormones.     

Atrial natriuretic hormone, vessel dilator, long acting natriuretic hormone, and kaliuretic hormone decrease circulating prolactin concentrations.

The present investigation was designed to test whether four cardiac hormones--long acting natriuretic hormone, vessel dilator, kaliuretic hormone and atrial natriuretic hormone--decrease the circulating concentration of prolactin in humans (n = 30). Vessel dilator, kaliuretic hormone, long acting natriuretic hormone and atrial natriuretic hormone decreased the circulating concentration of prolactin to 3 %, 31 %, 27 %, and 23 % of control values, respectively, at the end of their infusions when infused at concentrations of 100 ng/kg body weight per minute for 60 minutes (p < 0.001 for each). Vessel dilator, kaliuretic hormone, long acting natriuretic hormone and atrial natriuretic hormone had sustained effects on modulating prolactin's concentrations, with circulating concentrations of 1 %, 64 %, 28 %, and 2 % of control values (p < 0.001) 3 hours after stopping their respective infusions. These results suggest that there are four circulating prolactin-inhibitory hormones in addition to the hypothalamic mediators, dopamine and corticotropin-releasing hormone, which modulate prolactin release. These peptide hormones' ability to decrease circulating prolactin concentrations may be mediated in part by dopamine and in part by their demonstrated ability to decrease corticotropin-releasing hormone concentrations, which stimulate prolactin release.     

Distribution of PER protein,pigment-dispersing hormone,prothoracicotropic hormone,and eclosion hormone in the cephalic nervous system of insects

Investigations performed on adult insects revealed that putative components of the central pacemaker, the protein Period (PER) and the pigment-dispersing hormone (PDH), are immunocytochemically detectable in discrete sets of brain neurons throughout the class of Insecta, represented by a bristletail, mayfly, damselfly, 2 locust species, stonefly, 2 bug species, goldsmith beetle, caddisfly, honeybee, and 2 blowfly species. The PER-positive cells are localized in the frontal protocerebrum and in most species also in the optic lobes, which are their only location in damselfly and goldsmith beetle. Additional PER-positive cells occur in a few species either in the deuto- and tritocerebrum or in the suboesophageal ganglion. The PER staining was always confined to the cytoplasm. The PDH immunoreactivity consistently occurs in a cluster of perikarya located frontoventrally at the proximal edge of the medulla. The mayfly and both locust species possess additional PDH neurons in 2 posterior cell clusters at the proximal edge of the medulla, and mayfly, waterstrider, and 1 of the blowfly species in the central brain. PDH-positive fibers form a fanlike arrangement over the frontal side of the medulla. Two or just 1 bundle of PDH-positive fibers run from the optic lobe to the protocerebrum, with collaterals passing over to the contralateral optic lobe. Antisera to the prothoracicotropic (PTTH) and the eclosion (EH) hormones, which in some insects regulate the molting and ecdysis rhythms, respectively, typically react with a few neurons in the frontal protocerebrum. However, the PTTH-positive neurons of the mayfly and the damselfly and the EH-positive neurons of the caddisfly are located in the suboesophageal ganglion. No PTTH-like antigen was detected in locusts, and no EH-like antigens were detected in the damselfly, stonefly, locusts, and the honeybee. There are no signs of co-localization of the PER-, PDH-, PTTH-, and EH-like antigens in identical neurons.     

Calcium metabolism, serum thyroid-stimulating hormone, prolactin, and growth hormone in spontaneously hypercholesterolemic rats

We have shown previously that spontaneously hypercholesterolemic (SHC) rats exhibit abnormal bone metabolism with advanced bone resorption, which develops with age. In this study, we measured serum levels of growth hormone, thyroid-stimulating hormone, and prolactin in addition to several parameters of calcium metabolism and renal function in young (6-week) and old (24-week) SHC rats and compared these with age-matched Sprague-Dawley rats. In young SHC rats, urinary excretion of hydroxyproline and serum levels of calcium were significantly elevated and excretion of protein into urine and urea nitrogen in the serum were normal, suggesting that calcium metabolism was abnormal without kidney dysfunction at this age. Serum growth hormone and thyroid-stimulating hormone levels were markedly higher (20- to 30-fold and 4- to 5-fold, respectively) in young and old SHC rats, whereas serum prolactin levels were similar. A high level of serum thyroid-stimulating hormone was associated with elevated levels of thyroxine and triiodothyronine in young SHC rats, but not old ones. These results demonstrate that the rat exhibits abnormalities in endocrine function as well as calcium metabolism preceding the occurrence of renal dysfunction.     

Mapping polypeptide hormone genes in the mouse: somatostatin, glucagon, calcitonin, and parathyroid hormone

Mouse-Chinese hamster hybrids segregating mouse chromosomes were analyzed by Southern hybridization techniques to map the genes for somatostatin (Smst), glucagon (Gcg), calcitonin (Calc), and parathyroid hormone (Pth). The mouse gene for somatostatin, detected on a 20-kb EcoRI fragment, is located on mouse chromosome 16. Glucagon cDNA hybridized to a 14-kb EcoRI fragment residing on chromosome 2. Calcitonin and parathyroid hormone genes, detected on 7.8-kb HindIII and 6.0-kb BamHI fragments, respectively, were on mouse chromosome 7. The calcitonin and parathyroid hormone genes appear to be part of a larger linkage group which has been conserved in mouse and man.     

Ontogeny of growth hormone, prolactin, luteinizing hormone, and testosterone secretory patterns in the ram

The ontogenetic changes that occur in secretory patterns of growth hormone (GH), prolactin (Prl), luteinizing hormone (LH), and testosterone (T) in rams maintained in constant photoperiod were examined. Nine ram lambs were moved to individual pens in a controlled environment (12L: 12D cycle; 18-24 degrees C temperature) at 66 days of age. Blood samples were collected via indwelling cannulae at 15-min intervals for an 8-h period at 80, 136, 192, 248, and 304 days of age. Plasma concentrations of GH, Prl, LH, and T were quantitated and parameters of the secretory patterns determined. Mean concentration of GH tended to decline with age, probably because the amplitude of secretory peaks was significantly reduced with age. There were no age-associated changes in basal concentration of GH or incidence of GH peaks. There was an increase in Prl secretion (as estimated by mean concentration) at 136 and after 248 days of age. Significant age-associated changes occurred in all parameters of LH and T secretion. At the younger ages, testosterone concentrations were low and LH concentrations were elevated. At the older ages the relationship was reversed, with LH low and testosterone high. There were no significant correlations between frequency and magnitude of LH and T peaks. The significant correlations present among parameters of LH and T secretion were between basal concentration of LH and overall mean concentration and basal concentration of T. These results suggest that LH may not be the sole tropic stimulator of acute T secretion.     

Somatocrinin,growth hormone releasing factor,stimulates secretion of growth hormone in anesthetized rats

The synthetic replicate of a 44 amino acid peptide isolated from a human pancreatic tumor which had caused acromegaly possesses high specific activity to release growth hormone (GH) in anesthetized male rats. The GH secretion induced by this peptide is dose-dependent from 50 ng to 1 μg, with plasma GH concentrations increasing more than 10-fold within 5 min of iv administration at the higher doses. Two enzymatic degradation products of the 44 residue peptide were also isolated and consist of the first 37 and 40 amino acids. All three peptides appear to possess similar potency, on a molar basis, $\text{in}\text{vivo}$, contrary to $\text{in}\text{vitro}$ results. The specificity of these peptides on GH release was shown by their failure to alter plasma concentrations of prolactin (PRL), thyroid-stimulating hormone (TSH), luteinizing hormone (LH), follicle-stimulating hormone (FSH) and corticosterone. Based on these $\text{in}\text{vivo}$ results, the three peptides with serve as powerful tools with which to investigate the mechanisms of GH secretion.     

Age-dependent effect of Freund's adjuvant on 24-hour rhythms in plasma prolactin, growth hormone, thyrotropin, insulin, follicle-stimulating hormone, luteinizing hormone and testosterone in rats

The effect of Freund's adjuvant administration on 24-hour changes of plasma prolactin, growth hormone (GH), thyrotropin (TSH), insulin, follicle-stimulating hormone (FSH), luteinizing hormone (LH) and testosterone were studied in young (2 months) and aged (18 months) male Wistar rats. Rats were injected s.c. with Freund's adjuvant or adjuvant's vehicle and, 18 days later, they were killed at 6 different time intervals throughout a 24-hour cycle to measure circulating hormone levels by specific RIAs. Young rats receiving adjuvant's vehicle exhibited significant time-of-day-dependent variations in plasma TSH, LH and testosterone, with maximal levels at 1300 h, 0100 h and 1700 h, respectively. Prolactin and insulin levels, analyzed globally in a factorial ANOVA, showed significant time-of-day changes with maximal levels at 1300 - 1700 h and 2100 h, respectively. The daily rhythms in plasma LH and testosterone found in young rats were not longer observed in Freund's adjuvant-injected rats, while as far as TSH, a second peak was observed at 0100 h after Freund's adjuvant administration. Twenty-four hour rhythms in circulating TSH, LH and testosterone were blunted in old rats receiving either Freund's adjuvant or its vehicle. Aged rats exhibited significantly higher circulating levels of prolactin, and lower levels of GH, TSH, FSH and testosterone. The results indicate that secretion of prolactin, GH, TSH, FSH and testosterone are age-dependent, as are the responses of TSH, LH and testosterone to Freund's adjuvant administration.     

Twenty-four hour rhythms of hypothalamic corticotropin-releasing hormone, thyrotropin-releasing hormone, growth hormone-releasing hormone and somatostatin in rats injected with Freund's adjuvant

The effect of Freund's adjuvant injection on 24-hour variation of hypothalamic corticotropin-releasing hormone (CRH), thyrotropin-releasing hormone (TRH), GH-releasing hormone (GRH) and somatostatin levels was examined in adult rats kept under light between 0800 and 2000 h daily. Groups of rats receiving Freund's complete adjuvant or its vehicle 3 days before sacrifice were killed at six different time intervals throughout a 24-hour cycle. In the median eminence, adjuvant vehicle-injected rats exhibited significant 24-hour variations for the four hormones examined, with maxima at noon. These 24-hour rhythms were inhibited or suppressed by Freund's adjuvant injection. In the anterior hypothalamus of adjuvant vehicle-treated rats, CRH content peaked at 1600 h, while two peaks were found for TRH and GRH levels, i.e., at 2400-0400 h and 1600 h. Freund's adjuvant injection suppressed 24-hour rhythm of anterior hypothalamic CRH, TRH and GRH content and uncovered a peak in anterior hypothalamic somatostatin levels at 0400 h. In the medial hypothalamus of adjuvant vehicle-treated rats, significant 24-hour variations were detectable for TRH (peaks at 1600 and 2400 h) and somatostatin (peak at 2400 h) which disappeared after Freund's adjuvant injection. In the posterior hypothalamus of adjuvant vehicle-treated rats, two peaks were apparent for CRH, TRH and somatostatin levels, i.e. at 1600 h and 2400-0400 h, this hormonal profile remaining unmodified after Freund's adjuvant administration. The administration of the immunosuppressant drug cyclosporine (5 mg/kg, 5 days) impaired the depressing effect of Freund's adjuvant injection on CRH, TRH and somatostatin content in median eminence, but not that on GRH. In the anterior hypothalamus, cyclosporine generally prevented the effect of immunization on hormone levels an revealed a second maximum in TRH at 0400 h. Cyclosporine also restored 24-hour variations in TRH and somatostatin levels of medial hypothalamus of Freund's adjuvant-injected rats but was unable to modify them in the posterior hypothalamus. The results further support the existence of a significant effect of immune-mediated inflammatory response at an early phase after Freund's adjuvant injection on hypothalamic levels which was partially sensitive to immunosuppression by cyclosporine.     

Ethnic differences in adrenocorticotropic hormone, cortisol and corticotropin-releasing hormone during pregnancy

Significant ethnic disparities exist in reproductive outcomes. A potential contributing factor may be the functioning of the hypothalamic-pituitary-adrenal (HPA) axis and placenta during pregnancy. In the present study, levels of cortisol, ACTH and CRH were determined longitudinally from the plasma of 310 African American, Hispanic and non-Hispanic White women at 18-20, 24-26 and 30-32 weeks' gestation. During pregnancy, African American women exhibited lower levels of cortisol than non-Hispanic women and higher levels of ACTH than Hispanic women. The trajectory of CRH increase also differed by ethnicity, with African Americans exhibiting the lowest levels both early and late in pregnancy. Higher levels of cortisol at 18-20 weeks were associated with higher levels of CRH at 30-32 weeks among the African American and Hispanic women, but not among non-Hispanic women. Ethnic differences persisted when adjusting statistically for sociodemographic and biomedical factors. The findings are consistent with the possibility that ethnic disparities in adverse birth outcomes may be due, in part, to differences in HPA axis and placental function.     

Juvenile hormone titers,juvenile hormone biosynthesis,ovarian development and social environment in Bombus terrestris

The effects of the social environment and age on juvenile hormone (JH) and reproduction were investigated by measuring ovarian development, hemolymph levels of JH III, and rates of JH biosynthesis from the same individual bumble bees (Bombus terrestris). Differences in social environment were associated with differences in rates of JH biosynthesis, JH titer and ovarian development. Young queenless workers had a higher rate of JH biosynthesis, JH titer and ovarian development than queenright (QR) workers of similar age. Dominant workers in QR colonies had a higher rate of JH biosynthesis, JH titer and ovarian development than low ranked workers of similar size. There was a positive correlation between JH titer and ovarian development, but no correlation between rate of JH biosynthesis and ovarian development or between JH biosynthesis and JH titer. Both JH titer and rate of JH biosynthesis increased with age from emergence to 3 days of age, but 6-day-old workers, egg-laying workers, and actively reproducing queens had high JH titers and highly developed ovaries but low rates of JH biosynthesis. These results show that reproduction in B. terrestris is strongly affected by the social environment and the influence of the environment on reproduction is mediated by JH. Our data also indicate that the rate of JH biosynthesis measured in vitro is not a reliable indicator of JH titer or ovarian development in B. terrestris; possible reasons are discussed.     

Relaxin,a male hormone?

Summary Convincingly demonstrated by immunocytological methods in females of several mammalian species, relaxin has not yet been localized in the male. Immunocytologically, a related antigen was identified in adult normal boar testes using an anti- [NIH P-relaxin/HSA] antiserum free of anti HSA Abs. A strong reaction was observed in interstitial cells, a weaker but very clear one in Sertoli cells. NIH P-relaxin and HCl-acetone extracts of either corpora lutea from pregnant sows or boar testes inhibited the immunofluorescence of the reactive structures in the boar testes as well as in ovaries of pregnant sows. Ethanol-acetone precipitates from boar rete testis or caudal epididymal fluids inhibited the reaction of interstitial and Sertoli cells, but this inhibition in the sow was limited only to degenerative ovarian structures, probably due to an insufficient level of inhibiting antigen in these two seminal fluids, in contrast with the very high concentration of relaxin in luteal cells of pregnant sows. Specific immunofluorescence was observed neither in ectopic testes of adult monocryptorchid boars (contrary to scrotal testes in these same animals) nor in testes of prepuberal pigs. The specificity and meaning of these results are discussed.     

TSH, the bone suppressing hormone

The skeleton is a dynamic organ whose structural integrity depends on constant remodeling, controlled by many local and systemic factors. In this issue of Cell, identify thyroid-stimulating hormone (TSH) as an important regulator of this process.     

Body fat affects mouse reproduction,ovarian hormone release,and response to follicular stimulating hormone

We investigated the effects of body fat content on mouse fecundity, ovarian hormone release, and their response to follicle stimulation hormone (FSH). 4 types of females were produced: lean (group 1), normal (group 2), slightly fat (group 3), and significantly fat (group 4). The body weights, fat content, fertility rate, embryo number produced, retarded and degenerated embryo percentage, the release of progesterone (P4), testosterone (T), and insulin-like growth factor I (IGF-I) by isolated ovaries cultured with and without FSH (1.0 IU/mL medium) were evaluated. A gradual increase in body weight and fat contents from groups 1 to 4 was observed. Group 2 had higher fertility rate than those from the other groups. Groups 2 and 3 had fewer retarded and degenerated embryos that those from groups 1 and 4. Embryo production rate was not different among the groups. P4 and T secretion was higher from group 4 than in those from groups 1–3; secretion of IGF-I of group 3 was less than that of groups 1, 2, and 4. FSH promoted ovarian T output in all groups and stimulated ovarian P4 release in groups 1, 3, and 4, but not in group 2. FSH did not affect IGF-I release in any group. Therefore, both malnutrition and overfeeding can affect body weight and fat content in female mice, reducing embryo quality or developmental capacity, but not fertility and embryo production. Excess weight or fat can have stimulatory effects on ovarian P4 and T, but inhibitory effects on ovarian IGF-I release. Both leanness and excess weight or fat can induce the stimulatory action of FSH on ovarian P4.     

Regulation of baboon fetal adrenal androgen production by adrenocorticotropic hormone, prolactin, and growth hormone

Factors other than adrenocorticotropic hormone (ACTH) are thought to influence fetal adrenal steroidogenesis during primate pregnancy. Therefore, we determined the effects of prolactin (Prl), growth hormone (GH), and human chorionic gonadotropin (hCG) as well as ACTH on steroid secretion by collagenase-dispersed baboon fetal adrenal cells. Adrenal glands were obtained from seven baboon (Papio anubis) fetuses following cesarean section at Day 100-107 of gestation (term = Day 184). Tissue was minced with a fine scissors and cells were dispersed with 0.2% collagenase, then washed with Medium 199 containing penicillin/streptomycin. Cells (0.5 X 10(4)) were placed in 4 ml Medium 199 with or without 10 nmol ovine Prl, ovine GH, or ACTH, or 50 nmol hCG. After 18 h incubation (37 degrees C), cells were separated by centrifugation and the quantities of cortisol (F), dehydroepiandrosterone (DHA), and DHA-sulfate (DHAS) secreted into the medium were determined. In controls, DHA secretion [224 +/- 96 ng/(24 h X 10(5) cells] was greater (P less than 0.05) than that of DHAS (20 +/- 12) and F (14 +/- 12). Adrenocorticotropic hormone, Prl, and GH stimulated (P less than 0.05) DHA secretion by 370% +/- 71%, 215% +/- 61%, and 292% +/- 73%, respectively; hCG was not effective. Due primarily to the relatively low secretion rates, DHAS and F secretion were not altered by hormonal treatment. Moreover, addition of 20 nmol progesterone to the medium in the presence or absence of ACTH did not influence F production. These findings indicate that the baboon fetal adrenal at midgestation does not utilize placental progesterone for F synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Puberty in the male chimpanzee: time-related variations in luteinizing hormone, follicle-stimulating hormone, and testosterone

The onset of pubertal testicular growth (Po) occurred in 12 out of 20 male chimpanzees surveyed monthly for at least 3.7 yr. When animals were synchronized according to Po, the mean weight gain was found to be higher before than after Po, and testicular volume started to rise immediately after Po. The earlier significant hormonal events were a rapid rise in LH and a slight testosterone increase occurring 6 mo before Po. Thereafter, the levels of LH remained elevated while testosterone continued to rise in parallel with the testicular volume. FSH levels increased suddenly at Po, 6 mo after the LH increase. FSH remained elevated for only 9 mo, then dropped to prepubertal levels. The dissociation between onsets of pubertal increases in LH and FSH secretions suggests that the complete reawakening of the hypothalamic-pituitary unit lasts several months. The secondary drop of FSH, occurring at the time of spermarche, may be induced by factor(s) secreted by the testis.