Role of the adrenal cortex in chronic stress-induced inhibition of prolactin secretion in male rats

1989 ◽  
Vol 120 (2) ◽  
pp. 269-273 ◽  
Author(s):  
A. López-Calderón ◽  
C. Ariznavarreta ◽  
M. D. Calderón ◽  
J. A. F. Tresguerres ◽  
M. I. Gonzalez-Quijano
Keyword(s):  
Adrenal Cortex ◽  
Chronic Stress ◽  
Immobilization Stress ◽  
Plasma Concentrations ◽  
Inhibitory Effect ◽  
Prolactin Secretion ◽  
Male Rats ◽  
Prolonged Release ◽  
Plasma Prolactin

ABSTRACT The response of prolactin to chronic stress in intact, adrenalectomized and adrenomedullectomized male rats was studied. Immobilization stress in intact animals induced a significant increase in plasma concentrations of prolactin after 20 and 45 min and a significant decrease when the rats were submitted to chronic restraint (6 h daily for 4 days). Five weeks after adrenomedullectomy, plasma prolactin and corticosterone responses to chronic stress were not modified. In contrast, the inhibitory effect of chronic stress on prolactin secretion was totally suppressed by adrenalectomy. When treated with dexamethasone during the 4 days of restraint, adrenalectomized stressed rats showed similar plasma concentrations of prolactin to the intact stressed rats. These data indicate that the adrenal cortex is able to play an inhibitory role on prolactin secretion during stress only through a prolonged release of glucocorticoids. Journal of Endocrinology (1989) 120, 269–273

Role of LHRH in the gonadotrophin response to restraint stress in intact male rats

1990 ◽  
Vol 124 (2) ◽  
pp. 241-246 ◽  
Author(s):  
A. López-Calderón ◽  
M. I. Gonzaléz-Quijano ◽  
J. A. F. Tresguerres ◽  
C. Ariznavarreta
Keyword(s):  
Chronic Stress ◽  
Negative Correlation ◽  
Restraint Stress ◽  
Plasma Concentrations ◽  
Inhibitory Effect ◽  
Male Rats ◽  
Intact Male ◽  
Gonadotrophin Secretion ◽  
Site Of Action

ABSTRACT A hypothalamic site of action has been hypothesized for the inhibitory effect of chronic stress on gonadotrophin secretion. The aim of the present study was to examine the temporal changes in hypothalamic LHRH content and gonadotrophin secretion during restraint stress, and the pituitary responsiveness to LHRH stimulation in chronically stressed rats. Adult male rats were killed after being restrained for 0, 20, 45, 90, 180 and 360 min or for 6 h daily over 2, 3 and 4 days. After 20–45 min of stress there was an increase in plasma concentrations of LH (P<0·01) and a decrease in hypothalamic LHRH content (P<0·01), suggesting a negative correlation between plasma LH and hypothalamic LHRH concentrations. Plasma concentrations of FSH were also increased by restraint, but the FSH response was slower and less than the plasma LH response, being significant after 90 min of restraint. Plasma LH and FSH and hypothalamic LHRH concentrations were decreased in chronically stressed rats. In rats restrained for 6 h daily over 4 days, the response of plasma gonadotrophins to administration of 500 ng LHRH was enhanced 45 min after the injection. On the basis of these observations we concluded that in the intact rat, stress may acutely stimulate LHRH and gonadotrophin secretion, and the inhibitory effect of chronic stress on plasma LH and FSH seems not to be due to a reduction in pituitary responsiveness to LHRH, but rather to a decrease in LHRH secretion. Journal of Endocrinology (1990) 124, 241–246

Involvement of the adrenal gland in the suckling-induced decrease in LH and FSH secretion and the concomitant increase in prolactin secretion in the rat

1990 ◽  
Vol 125 (2) ◽  
pp. 279-285 ◽  
Author(s):  
K. Taya ◽  
S. Sasamoto
Keyword(s):  
Adrenal Gland ◽  
Ovarian Function ◽  
Plasma Concentrations ◽  
Prolactin Secretion ◽  
Plasma Prolactin ◽  
Luteal Function ◽  
Follicular Maturation ◽  
High Concentrations ◽  
Ovulatory Follicles

ABSTRACT The role of the adrenal gland in the regulation of gonadotrophin and prolactin secretion in the lactating rat was investigated. Changes in secretion of LH, FSH, prolactin, ACTH, β-lipotrophin (β-LPH), inhibin, corticosterone and progesterone after adrenalectomy were examined during the second half of lactation. Follicular maturation was determined by the ability of the follicles to ovulate in response to 10IU human chorionic gonadotrophin (hCG). Adrenalectomy on day 10 of lactation prevented an increase in plasma concentrations of LH and FSH in response to ovariectomy performed at the same time as adrenalectomy, and markedly stimulated secretion of ACTH, β-LPH and prolactin. Adrenalectomy reduced the number of follicles capable of ovulating in response to hCG. Concentrations of inhibin and progesterone in the plasma significantly decreased after adrenalectomy, indicating that development of ovulatory follicles and luteal function had been suppressed. Abolishing the increase in plasma concentrations of LH and inducing a decrease in FSH in the plasma by adrenalectomy therefore prevented maturation of a new set of follicles usually seen during the second half of lactation in rats. The decrease in plasma concentrations of LH also inhibited the ability of the corpus luteum to secrete progesterone, although high concentrations of plasma prolactin were maintained in adrenalectomized lactating rats. These results indicate that the pituitary-adrenal system is capable of influencing the maintenance of a normal secretion of gonadotrophin and prolactin as well as the maintenance of ovarian function during lactation in the rat. Journal of Endocrinology (1990) 125, 279—285

scholarly journals Stress Modifies the Expression of Glucocorticoid-Responsive Genes by Acting at Epigenetic Levels in the Rat Prefrontal Cortex: Modulatory Activity of Lurasidone

2021 ◽  
Vol 22 (12) ◽  
pp. 6197
Author(s):  
Paola Brivio ◽  
Giulia Sbrini ◽  
Letizia Tarantini ◽  
Chiara Parravicini ◽  
Piotr Gruca ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Chronic Stress ◽  
Chronic Mild Stress ◽  
Male Rats ◽  
Mild Stress ◽  
Experimental Conditions ◽  
Glucocorticoid Responsive Element ◽  
Responsive Element

Epigenetics is one of the mechanisms by which environmental factors can alter brain function and may contribute to central nervous system disorders. Alterations of DNA methylation and miRNA expression can induce long-lasting changes in neurobiological processes. Hence, we investigated the effect of chronic stress, by employing the chronic mild stress (CMS) and the chronic restraint stress protocol, in adult male rats, on the glucocorticoid receptor (GR) function. We focused on DNA methylation specifically in the proximity of the glucocorticoid responsive element (GRE) of the GR responsive genes Gadd45β, Sgk1, and Gilz and on selected miRNA targeting these genes. Moreover, we assessed the role of the antipsychotic lurasidone in modulating these alterations. Chronic stress downregulated Gadd45β and Gilz gene expression and lurasidone normalized the Gadd45β modification. At the epigenetic level, CMS induced hypermethylation of the GRE of Gadd45β gene, an effect prevented by lurasidone treatment. These stress-induced alterations were still present even after a period of rest from stress, indicating the enduring nature of such changes. However, the contribution of miRNA to the alterations in gene expression was moderate in our experimental conditions. Our results demonstrated that chronic stress mainly affects Gadd45β expression and methylation, effects that are prolonged over time, suggesting that stress leads to changes in DNA methylation that last also after the cessation of stress procedure, and that lurasidone is a modifier of such mechanisms.

Differential effects of passive immunization with somatostatin antiserum on adenohypophysial hormone secretions in starved rats

1986 ◽  
Vol 109 (2) ◽  
pp. 169-174 ◽  
Author(s):  
J. N. Hugues ◽  
A. Enjalbert ◽  
E. Moyse ◽  
C. Shu ◽  
M. J. Voirol ◽  
...  
Keyword(s):  
Binding Capacity ◽  
Hormone Secretion ◽  
Plasma Concentrations ◽  
Passive Immunization ◽  
Negative Control ◽  
Prolactin Secretion ◽  
Male Rats ◽  
Minimal Effective Dose ◽  
Gh Secretion

ABSTRACT The role of somatostatin (SRIF) on adenohypophysial hormone secretion in starved rats was reassessed by passive immunization. Because of the absence of pulsatile GH secretion in starved rats, the effects of the injection of SRIF antiserum on GH levels can be clearly demonstrated. To determine whether starvation modifies the sensitivity of the adenohypophysis to SRIF, we measured 125I-labelled iodo-N-Tyr-SRIF binding. There was no difference in the dissociation constant (Kd) nor in the maximal binding capacity (Bmax) in fed (n = 15) and starved (n = 15) animals (Kd = 0·38 ± 0·09 (s.e.m.) and 0·45 ± 0·09 nmol; Bmax = 204 ± 39 and 205 ± 30 fmol/mg protein respectively). Administration of SRIF antiserum resulted in a dose-dependent increase in plasma concentrations of GH, TSH and prolactin. The minimal effective dose of SRIF antiserum was 50 μl for GH, 100 μl for TSH and 200 μl for prolactin. Our results show that: (1) starvation does not modify adenohypophysial SRIF-binding sites, (2) in starved male rats endogenous SRIF exerts a negative control on prolactin secretion in vivo and (3) sensitivity to endogenous SRIF seems to be different for each hypophysial cell type. J. Endocr. (1986) 109, 169–174

Serotoninergic control of prolactin secretion in prepubertal male rats

1994 ◽  
Vol 131 (5) ◽  
pp. 547-554 ◽  
Author(s):  
Enrique Aguilar ◽  
Antonio Ranchal ◽  
Manuel Tena-Sempere ◽  
Leonor Pinilla
Keyword(s):  
Specific Inhibitor ◽  
Prolactin Secretion ◽  
Male Rats ◽  
Serotoninergic System ◽  
Selective Agonist ◽  
5 Ht Uptake ◽  
Releasing Effect

Aguilar E, Ranchal A, Tena-Sempere M, Pinilla L. Serotoninergic control of prolactin secretion in prepubertal male rats. Eur J Endocrinol 1994;131:547–54. ISSN 0804–4643 The role of the serotoninergic system in the control of prolactin (PRL) secretion has been studied in prepubertal male rats. Serum PRL concentration was measured in 16-day-old male rats at different times after the administration of 5-hydroxytryptophan (5-HTP), a precursor of serotonin (5-HT) synthesis, alone or in combination with fluoxetine, a specific inhibitor of 5-HT uptake; dl-p-parachlorophenylalanine (PCPA), an inhibitor of 5-HT synthesis; and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), a selective agonist of 5-HT1A receptors. Also, serum PRL concentration and pituitary content were measured after 5-HTP administration in castrated males implanted with silastic capsules containing testosterone or 5α-androstane-3α,17β-diol (α-diol). We found that: the reduction in serotoninergic activity after PCPA administration did not modify serum PRL concentrations; the stimulatory effect of 5-HTP on PRL secretion was not observed before day 16; the effects of 5-HTP or 5-HTP and fluoxetine were similar in intact and orchidectomized males; a significant increase in PRL secretion took place after 8-OH-DPAT administration; the duration of the stimulatory effect of 5-HTP increased after α-diol treatment; and pituitary PRL content increased after 5-HTP injection in intact males and decreased in castrated males treated with testosterone or α-diol. Therefore, we conclude that: the PRL-releasing effect of 5-HTP remains after orchidectomy; activation of 5-HT1A receptors may mediate, at least partially, the effect of 5-HTP; testosterone and α-diol affect the duration of PRL release after 5-HTP administration differently; and testicular factors other than androgens might be involved in the effects of 5-HTP on PRL pituitary accumulation. Enrique Aguilar, Department of Physiology, Faculty of Medicine, Córdoba University, 14004 Córdoba, Spain

Involvement of physiological prolactin levels in growth and prolactin receptor content of prostate glands and testes in developing male rats

1992 ◽  
Vol 132 (3) ◽  
pp. 449-459 ◽  
Author(s):  
B. Pérez-Villamil ◽  
E. Bordiú ◽  
M. Puente-Cueva
Keyword(s):  
Body Weight ◽  
Male Rats ◽  
Ventral Prostate ◽  
Serum Prolactin ◽  
Plasma Prolactin ◽  
Stages Of Development ◽  
Continuous Increase ◽  
Testosterone Levels ◽  
Testicular Weight

ABSTRACT We have investigated the role of physiological prolactin levels in the development of prepubertal male rats. Prolactin GH and testosterone levels, as well as body, ventral prostate and testicular weight, have been analysed in both control and bromocriptine-treated rats between 21 and 60 days of life. Furthermore the role of prolactin in the regulation of its own receptors has also been studied during the same period. In control rats, prolactin levels showed a prepubertal peak of secretion at 25 days of age. At this time GH and testosterone levels were low and did not show any significant variation. After this age, prolactin levels increased more gradually; determinations of GH showed great variation with low levels in most of the rats and very high values in the other animals; testosterone levels remained low until day 35 after which they increased. Simultaneously with the serum prolactin peak on day 25, a decrease in prolactin-binding capacity of ventral prostate glands, was observed and a maximum rate of body, prostate and testicular weight gain was obtained. Furthermore, in rats with pharmacologically suppressed serum prolactin levels (lower than 1 μg/l), prolactin binding to prostate glands as well as the weight of body, ventral prostate and testes were lower than in control animals. When results were expressed in mg prostate or testes/g body weight, testes from 25-day-old treated rats weighed significantly less than controls. The later stages of development, from days 25 to 60, were characterized by an initial decline in serum prolactin levels at 29 days of age which was followed by a continuous increase until adult values were reached. During this period, prostatic prolactin receptors which were at their lowest value at 33 days of age showed a gradual rise parallel with the observed increase in plasma prolactin levels. When testicular tissue was analysed, no changes in prolactin-binding sites caused by sexual maturation were observed. The present results indicate that physiological prolactin secretion has a specific effect on the normal increase in the prostate, testes and body weight and clearly is also implicated in the regulation of its prostatic receptors at the earlier stages of development. Journal of Endocrinology (1992) 132, 449–459

Regulation of the photoperiod-induced cycle in the peripheral blood concentrations of β-endorphin and prolactin in the ram: role of dopamine and endogenous opioids

1990 ◽  
Vol 127 (3) ◽  
pp. 461-469 ◽  
Author(s):  
E. Ssewannyana ◽  
G. A. Lincoln
Keyword(s):  
Plasma Concentrations ◽  
Prolactin Secretion ◽  
Endogenous Opioids ◽  
Fold Change ◽  
Opioid Antagonist ◽  
Light Cycle ◽  
Blood Concentrations ◽  
The Mean ◽  
Short Days

ABSTRACT In a group of adult Soay rams housed indoors under an artificial light cycle of alternating 16-week periods of long and short days, there was a conspicuous longterm cycle in the peripheral plasma concentrations of β-endorphin and prolactin. The levels of β-endorphin were highest under short days and lowest under long days (15-fold change), and inversely related to the changes in the plasma levels of prolactin (120-fold change). The role of dopamine in the control of β-endorphin and prolactin was investigated in a series of experiments, conducted under both long and short days, in which rams were treated with dopamine receptor agonists (dopamine and bromocriptine) and antagonists (pimozide and sulpiride). Naloxone (opioid antagonist) was also administered to assess the additional involvement of endogenous opioids. Dopamine injected i.v. (6·6 mg/kg every 10 min) did not significantly affect the mean plasma concentrations of β-endorphin and prolactin under either long or short days. Pimozide (0·08 mg/kg i.m. every 2 h) caused a large increase in the mean plasma concentrations of β-endorphin and prolactin under long days but not short days. Naloxone (1·6 mg/kg, i.v.), administered alone or in combination with dopamine or pimozide, had no effect on the mean plasma concentrations of β-endorphin and prolactin, except under short days when, combined with pimozide, it induced an increase in the plasma concentrations of the two polypeptides. Bromocriptine (0·06 mg/kg, s.c.) caused a significant decrease in the plasma concentrations of both β-endorphin and prolactin; this effect was most marked at the times of increased secretion (under short days for β-endorphin and under long days for prolactin). Sulpiride (0·59 mg/kg, s.c.) produced the converse effect and caused an increase in the plasma concentrations of β-endorphin and prolactin with the amplitude and duration of the effect varying with the stage of the photoperiod-induced cycle. From these results in the Soay ram, we conclude that dopamine inhibits β-endorphin and prolactin secretion by way of D2 receptors under both long and short days. Endogenous opioids interact with dopamine, augmenting this inhibition under short days. Differences in the acute responses in the secretion of β-endorphin and prolactin, and the inverse relationship between β-endorphin and prolactin during the cycle, indicate that different regulatory systems involving dopamine influence the two pituitary polypeptides. Journal of Endocrinology (1990) 127, 461–469

Somatostatin Inhibits prolactin secretion in the estradiol primed male rat

1981 ◽  
Vol 59 (10) ◽  
pp. 1082-1088 ◽  
Author(s):  
G. R. Cooper ◽  
S. H. Shin
Keyword(s):  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Blocking Agent ◽  
Prolactin Secretion ◽  
Male Rats ◽  
Male Rat ◽  
Dependent Manner ◽  
Intact Male ◽  
Plasma Prl

Somatostatin inhibits not only growth hormone secretion, but also the secretion of several other hormones. The role of somatostatin in prolactin (PRL) secretion has not been clearly demonstrated. The present study was undertaken to examine the effects of somatostatin on rat PRL secretion in several different circumstances where the circulating PRL level is elevated: (1) the estradiol primed intact male rat, (2) normal and (3) estradiol primed rats pretreated with pimozide, (4) normal and (5) estradiol primed hypophysectomized male rats with adenohypophyses grafted under the kidney capsule (HAG rat). Blood samples (70 μL) were taken every 2 min via an indwelling atrial cannula from conscious, unrestrained animals. In the estradiol primed intact rats, a bolus injection of somatostatin (10, 100, and 1000 μg/kg) lowered PRL levels in a dose-dependent manner. When the PRL concentration was elevated by the administration of pimozide (3 mg/kg), a dopaminergic receptor blocking agent, somatostatin was ineffective in decreasing plasma PRL concentration but the PRL concentration was lowered by somatostatin when the rat had been primed with estradiol. Somatostatin had no effect on the normal HAG rats, but lowered the plasma PRL concentration in the estradiol primed HAG rats. Since somatostatin inhibits PRL secretion only in the estradiol primed rats, it is suggested that estradiol priming creates a new environment, presumably via new or altered receptors, which can be inhibited by somatostatin.

The role of prolactin in the reactivation of hair follicles in relation to moulting in cashmere goats

1994 ◽  
Vol 143 (3) ◽  
pp. 441-448 ◽  
Author(s):  
P Dicks ◽  
A J F Russel ◽  
G A Lincoln
Keyword(s):  
Prolactin Secretion ◽  
Hair Follicles ◽  
Plasma Prolactin ◽  
Dose Rates ◽  
Significant Difference ◽  
Natural Photoperiod ◽  
Cashmere Goats ◽  
Ovine Prolactin ◽  
Voluntary Food Intake

Abstract The effects of the suppression or elevation of plasma prolactin concentrations in spring on the timing of the reactivation of the hair follicles and the timing of the spring moult were investigated in cashmere goats. Thirty eight adult female goats, housed under conditions of natural photoperiod at 55°55′N from mid-December until May, were allocated to four groups starting on 5 January: ten served as untreated controls, eight received 2 mg ovine prolactin subcutaneously every 12 h for 7 weeks (PRL), twelve received 35 mg bromocriptine intramuscularly every 14 days for 17 weeks (BCR) and eight received injections of both ovine prolactin and bromocriptine at the above dose rates for 7 weeks (PRL+BCR). In the PRL group there was an earlier reactivation of the secondary hair follicles (PRL vs control, proportion of secondary follicles in anagen, weeks 1–5, P<0·01) associated with an earlier moult of secondary fibres (cashmere) but no significant difference in the activity of the primary hair follicles. In the BCR group there was a delay in the reactivation of both the secondary and primary hair follicles (BCR vs control, proportion of secondary and primary hair follicles in anagen, weeks 5–13, P<0·01) and a delay in the moult. In the PRL+BCR group there was an early reactivation and moult similar to the PRL group. Voluntary food intake (VFI) and liveweight were also measured. Only in the BCR group was there a decrease in VFI compared with the controls but with no effect on liveweight. It was concluded that the seasonal increase in prolactin secretion which normally occurs in spring is causally involved in the reactivation of primary and secondary hair follicles and moulting in cashmere goats. Journal of Endocrinology (1994) 143, 441–448

Postreceptorial refractoriness of prolactin release mechanisms

1983 ◽  
Vol 61 (7) ◽  
pp. 676-684 ◽  
Author(s):  
R. Collu ◽  
J. R. Ducharme ◽  
D. Eljarmak ◽  
A. M. Marchisio ◽  
J. Bertrand ◽  
...  
Keyword(s):  
Binding Sites ◽  
Immobilization Stress ◽  
Significant Rise ◽  
Male Rats ◽  
Plasma Prolactin ◽  
Initial Value ◽  
Prolactin Release ◽  
Pituitary Glands ◽  
Plasma Prl

Whilc a first injection of the antidopaminergic benzamide drug, sulpiride, induced a large rise in plasma prolactin (PRL) levels in chronically cannulated adult male rats, a second injection given 2 h later was totally inactive although the pituitary content of the hormone was still 76% of the initial value. When the second injection was given 8 h after the first it was slightly effective, but when administered 24 h later it was as effective as the first. The second of two consecutive injections of haloperidol given at 2-h intervals, or an injection of morphine given 2 h after sulpiride, were incapable of inducing a release of PRL. Two hours after an injection of sulpiride, a 30-min period of immobilization stress induced a significant rise in plasma PRL levels. A significant rise in plasma PRL levels was also observed when larger doses of sulpiride were given 2 h after a first injection of the drug. Apomorphine was at least as effective an inhibitor of PRL secretion when given 2 h after sulpiride than when injected after saline. In vitro studies of dopaminergic binding sites revealed the presence, in pituitary glands of sulpiride-treated rats, of receptors not modified by the drug. These data suggest that the only plausible explanation for the ineffectiveness of the second of two consecutive injections of sulpiride is the development of a state of refractoriness of the mechanisms that subserve the release of PRL induced by suppression of the inhibitory dopaminergic tonus.

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