CIRCADIAN VARIATIONS IN THE PLASMA CONCENTRATION OF PROLACTIN IN THE ADULT MALE RAT

1978 ◽  
Vol 79 (1) ◽  
pp. 85-89 ◽  
Author(s):  
J. A. M. MATTHEIJ ◽  
J. J. M. SWARTS
Keyword(s):  
Circadian Rhythm ◽  
Plasma Concentration ◽  
Light Period ◽  
Male Rats ◽  
Male Rat ◽  
Circadian Variations ◽  
Blood Samples ◽  
Adult Male Rat ◽  
Preceding Period ◽  
Limit Stress

The occurrence of circadian variations in the concentration of prolactin in the plasma of 6- to 9-month-old male rats has been assessed in animals exposed to light for 14 h/day (lights on 06.00–20.00 h). Blood samples were obtained after decapitation, or from individual rats at regular intervals via a permanent cannula. Care was taken to limit stress during sampling. The concentration of prolactin in the plasma was significantly lower between 07.00 and 15.00 h than at other times. Between 15.00 and 20.00 h (during the light period), the concentration of prolactin was significantly higher in comparison with the preceding period, or with the remainder of the 24 h period. During the night, the concentration fluctuated, probably because of episodic releases of the hormone. The possible physiological significance of a circadian rhythm in the plasma concentration of prolactin and the implications for endocrine experimentation are discussed briefly.

Effects of acute administration of 2-hydroxylated metabolites of oestrogens on LH and prolactin secretion in male and female prepubertal rats

1984 ◽  
Vol 103 (3) ◽  
pp. 317-325
Author(s):  
A. K. Brar ◽  
G. Fink
Keyword(s):  
Plasma Concentration ◽  
Female Rats ◽  
Male Rats ◽  
Male Rat ◽  
Female Rat ◽  
Uterine Weight ◽  
Immature Female ◽  
Male And Female ◽  
Immature Male ◽  
Lh Release

ABSTRACT The effects of catechol oestradiol and catechol oestrone on the release of LH and prolactin were investigated in immature male and female Wistar rats. In male rats both catechol oestradiol and catechol oestrone significantly increased the plasma concentration of LH, and catechol oestradiol but not catechol oestrone significantly increased the plasma concentration of prolactin and decreased the pituitary concentration of LH. The parent oestrogens, oestradiol-17β and oestrone, had no effect on plasma LH concentrations, but both increased significantly the plasma concentration of prolactin, and oestrone but not oestradiol-17β increased the pituitary concentration of LH. In immature female rats, catechol oestradiol inhibited the surge of LH and the increase in uterine weight induced by injecting pregnant mare serum gonadotrophin (PMSG). The injection of oestrone induced an increase in the plasma concentration of LH which was about nine times greater than that produced by oestradiol-17β. There were no significant differences in the effects of these steroids on plasma prolactin concentration. These results (i) confirm that in the immature male rat catechol oestrogens can stimulate LH release and show that catechol oestradiol can increase prolactin release, (ii) show that catechol oestradiol can inhibit the stimulatory effects of PMSG on LH release and uterine weight in the immature female rat, and (iii) demonstrate that oestrone can stimulate LH release in the immature female rat. J. Endocr. (1984) 103, 317-325

DIURNAL TESTOSTERONE AND 17α-HYDROXYPROGESTERONE IN PERIPHERAL PLASMA OF YOUNG POST-PUBERTAL BULLS.

1976 ◽  
Vol 81 (3) ◽  
pp. 623-634 ◽  
Author(s):  
M. Thibier
Keyword(s):  
Circadian Rhythm ◽  
Plasma Concentration ◽  
Performance Test ◽  
Separate Occasion ◽  
Characteristic Pattern ◽  
Blood Samples ◽  
Peripheral Plasma ◽  
Four Seasons

ABSTRACT Testosterone1) and 17α-hydroxyprogesterone were measured in the peripheral plasma of 6 young post-pubertal bulls of 1 year of age, by separate radioimmunoassays. Samples were collected every hour for 25 h at the beginning of each of four seasons. On a separate occasion blood samples were collected from one bull every 10 min for 2 h. As a result of the study, testosterone and 17α-hydroxyprogesterone appeared to be secreted episodically. These two steroid peaks showed good correlation. Each 24 h period showed its own characteristic pattern of pulsatile changes. Episodic secretion seems to be progressive rather than rapid and short lived. No real circadian rhythm was observed but at about 10.00 a. m. a trough in these steroid secretions occurred. This was followed by an increase in peripheral plasma concentration. These troughs occurred at all seasons after the morning feed and while semen was being collected in the performance test station.

scholarly journals Some effects of dietary dextrose, fructose, liquid glucose and sucrose in the adult male rat

1966 ◽  
Vol 20 (2) ◽  
pp. 339-347 ◽  
Author(s):  
R. J. L. Allen ◽  
J. S. Leahy
Keyword(s):  
Adult Male ◽  
Body Weight Gain ◽  
Plasma Cholesterol ◽  
Liver Fat ◽  
Male Rats ◽  
Male Rat ◽  
Liver Protein ◽  
Cholesterol Levels ◽  
Adult Male Rat ◽  
The Mean

1. For 26 weeks, adult male rats were fed on diets containing about 80 % of carbohydrate, given as dextrose, fructose, liquid glucose, or sucrose; their performance was compared with that of rats receiving a standard laboratory cubed diet (41 B) containing 60 % of carbohydrate, mainly as starch. 2. More of diet 41 B was eaten than of any of the diets containing sugars, but only with dextrose was the mean body-weight gain significantly lower than with diet 41 B. 3. No significant differences in body length or girth were produced by the different diets. 4. Compared with those of rats given diet 41B, plasma cholesterol levels were significantly in- creased by fructose and sucrose and to a lesser extent by dextrose, but not by liquid glucose. 5. Compared with those given diet 41 B, the rats given fructose had heavier hearts, kidneys and livers, those given sucrose had heavier hearts and livers, and those given dextrose had heavier hearts. Those given fructose had the heaviest kidneys and livers, and heavier hearts than those given liquid glucose. The organ weights of those given liquid glucose and those given diet 41 B were not significantly different. 6. Compared with the values on diet 41B, carcass and liver fat were both significantly increased by sucrose and fructose but not by dex- trose or liquid glucose. With fructose, liver fat was almost double that with dextrose or liquid glucose. 7. Dry-matter contents of whole carcass and liver followed substantially the same pattern as did the fat contents. 8. Liver protein content was significantly lower on the 80 % carbohydrate diets. The reductions were greatest with fructose and sucrose.

Circadian variations in β-endorphin concentrations in pituitary and in some brain nuclei of the adult male rat

1983 ◽  
Vol 261 (2) ◽  
pp. 243-248 ◽  
Author(s):  
Bernard Kerdelhue ◽  
Michael Karteszi ◽  
Catherine Pasqualini ◽  
Alain Reinberg ◽  
Eva Mezey ◽  
...  
Keyword(s):  
Adult Male ◽  
Male Rat ◽  
Circadian Variations ◽  
Brain Nuclei ◽  
Adult Male Rat

Influence of pinealectomy on the suppression of gonadotrophin secretion induced by hyperprolactinaemia in the adult male rat

1983 ◽  
Vol 97 (3) ◽  
pp. 401-407 ◽  
Author(s):  
A. S. McNeilly ◽  
D. W. Lincoln
Keyword(s):  
Pineal Gland ◽  
Adult Male ◽  
Male Rats ◽  
Male Rat ◽  
Gonadotrophin Secretion ◽  
Adult Male Rat ◽  
Pituitary Glands ◽  
Hypothalamic Pituitary Axis

To investigate the role of the pineal gland in the long-term suppression of gonadotrophin secretion induced by prolactin, the effects of pinealectomy were studied in adult male rats with hyperprolactinaemia produced by the transplantation of two pituitary glands under the kidney capsule. Pinealectomy had no effect on basal levels of LH, FSH or prolactin. The presence of pituitary transplants induced a significant twofold increase in prolactin levels and a prolonged suppression in both LH and FSH. These changes were not affected by pinealectomy. Castration resulted in a similar rise in plasma levels of LH and FSH in rats with and without pituitary transplants. In control rats this rise in LH and FSH was reduced by testosterone-containing silicone elastomer implants (s.c) of 10 mm in length and delayed by implants of 30 mm. These rises in LH and FSH were significantly delayed (10-mm implant) or abolished (30-mm implant) in rats with pituitary transplants indicating an increase in sensitivity of the hypothalamic-pituitary axis to the negative feedback effects of testosterone in these animals compared to controls. These responses were not affected by pinealectomy. These results suggest that the pineal gland is not involved in the mechanism whereby pituitary grafts, possibly through their secretion of prolactin, cause long-term suppression of gonadotrophin secretion.

SERUM 5α-ANDROSTANE-3α,17β-DIOL, ANDROSTERONE AND TESTOSTERONE CONCENTRATIONS IN THE IMMATURE MALE RAT: INFLUENCE OF TIME OF DAY

1977 ◽  
Vol 75 (1) ◽  
pp. 177-178 ◽  
Author(s):  
W. H. MOGER ◽  
P. R. MURPHY
Keyword(s):  
Serum Testosterone ◽  
Temporal Variations ◽  
Time Of Day ◽  
Male Rats ◽  
Male Rat ◽  
Sprague Dawley ◽  
Circadian Variations ◽  
Adult Rat ◽  
Immature Male ◽  
Sprague Dawley Rats

Department of Physiology and Biophysics, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada, B3H 4H7 (Received 22 April 1977) The concentration of testosterone in the serum of the adult rat varies significantly over a 24 h period (Kinson & Lui, 1973; Howland, 1975; Wilson, McMillan, Seal & Ahmed, 1976). However, studies on circadian variations in serum testosterone concentrations in immature male rats have yielded conflicting results. Grotjan & Johnson (1976) reported significant changes with time in 25–26-day-old Holtzman rats, whereas Döhler & Wuttke (1976) did not observe significant changes in 13–18 or 25–30-day-old Sprague–Dawley rats maintained on the same lighting schedule (14 h light: 10 h darkness). Recently we reported that from 20–35 days of age, 5α-androstane-3α,17β-diol (androstanediol) is the predominant androgen in the circulation of male rats (Moger, 1977). This study was undertaken to determine temporal variations in the concentrations of androstanediol, androsterone and testosterone. Forty-nine male Sprague

Concentrations of immunoreactive tonin in submandibular glands and saliva of the rat

1986 ◽  
Vol 111 (1) ◽  
pp. 140-144
Author(s):  
Yukio Hirata ◽  
Masahiro Tomita ◽  
Takuo Fujita ◽  
Masao Ikeda
Keyword(s):  
Serine Proteases ◽  
Biological Significance ◽  
Male Rats ◽  
Male Rat ◽  
Female Rat ◽  
Adult Males ◽  
Angiotensin I ◽  
Adult Male Rat ◽  
Males And Females ◽  
Normal Males

Abstract. The submandibular gland (SMG) of the rat contains tonin, an enzyme of serine proteases, which specifically cleaves angiotensinogen and angiotensin I to yield angiotensin II directly. Using a specific RIA for rat tonin, the present study was performed to examine the concentrations of immunoreactive (IR) tonin in SMG of normal Wistar male rats with various ages, those in SMG and saliva of normal adult males and females, and also its SMG levels of castrated males and testosterone-treated females. The concentrations of IR-tonin in SMG of immature 4 week old male rats were very low but rose exponentially with increasing age to reach adult levels (3–6 μg/mg wet tissue) in male rats after 6 week old or more. SMG of the adult male rat contained 10-fold more IR-tonin than that of the female rat and male saliva contained 5-fold more IR-tonin than that of females. The concentrations of SMG IR-tonin in the castrated males fell to about one-tenth the levels of normal males, whereas SMG IR-tonin levels in the testosterone-treated females increased about ten times more than those of normal females. These data confirm the sexual dimorphism of rat SMG with respect to the concentrations of tonin and indicate that androgens play an important role in regulating the synthesis and/or storage of tonin in rat SMG. It is also suggested that tonin is secreted into saliva in concentrations reflecting its SMG levels. However, biological significance of tonin in SMG and saliva remains obscure.

scholarly journals Metabolism of a glutathione conjugate of 2-hydroxyoestradiol-17β in the adult male rat

1972 ◽  
Vol 126 (5) ◽  
pp. 1067-1071 ◽  
Author(s):  
John S. Elce
Keyword(s):  
Bile Duct ◽  
Adult Male ◽  
Analytical Techniques ◽  
Male Rats ◽  
Male Rat ◽  
Glutathione Conjugate ◽  
Before And After ◽  
Adult Male Rat ◽  
Derivatives Of

Adult male rats with cannulated or ligated bile ducts were given S-(2-hydroxyoestradiol-1-yl)[35S]glutathione, S-(2-hydroxy[6,7-3H2]oestradiol-1-yl)glutathione or S-(2-hydroxyoestradiol-1-yl)[glycine-3H]glutathione by intraperitoneal injection. The recovery of radioactivity in the bile of bile duct-cannulated rats was 33–86% and in the urine of bile duct-ligated rats was 54–105%. Oestrogen thioether derivatives of glutathione, cysteinylglycine, cysteine and N-acetylcysteine were isolated from bile; only the N-acetylcysteine derivatives could be identified in the urine. The steroid moiety was characterized by microchemical tests before and after treatment with Raney nickel: 2-hydroxyoestradiol-17β was released from the glutathione conjugate, and 2-hydroxyoestrone and 2-hydroxyoestrone 3-methyl ether from the other conjugates. From intact rats the recovery of administered radioactivity was about 15% in the urine and 5% in the faeces over a period of several days and the radioactivity appeared to be largely protein-bound. The results demonstrate that injected oestrogen–glutathione conjugate undergoes conversion into N-acetylcysteine derivatives in vivo. Oestrogen–glutathione conjugates formed in the intact rat may be excreted in an apparently non-steroidal, possibly protein-bound form, which would not be detected by current analytical techniques.

Diurnal Variations of Plasma Growth Hormone and Brain Monoamines in Adult Male Rats

1973 ◽  
Vol 51 (12) ◽  
pp. 890-892 ◽  
Author(s):  
R. Collu ◽  
J. C. Jéquier ◽  
J. Letarte ◽  
G. Leboeuf ◽  
J. R. Ducharme
Keyword(s):  
Growth Hormone ◽  
Adult Male ◽  
Physiological Role ◽  
Male Rats ◽  
Male Rat ◽  
Plasma Growth Hormone ◽  
Gh Secretion ◽  
Adult Male Rat ◽  
Plasma Gh

Brain levels of monoamines (MA) in the adult male rat show a diurnal pattern of secretion with noradrenaline (NA) and serotonin (5-HT) reaching a peak at 1300 and 1800, respectively, and dopamine (DA) showing a bimodal pattern with peaks at 0500 and 1800. Plasma growth hormone (GH) values fluctuate widely during the nycthemeral period. Statistically significant correlations between plasma GH and brain MA levels, confirming the existence of a physiological role of MA in the control of GH secretion, could not be demonstrated in the present study.

Tramadol Promotes Oxidative Stress, Fibrosis, Apoptosis, Ultrastructural and Biochemical alterations in the Adrenal Cortex of Adult Male Rat with Possible Reversibility after Withdrawal

2020 ◽  
Vol 26 (3) ◽  
pp. 509-523 ◽  
Author(s):  
Amany Mohamed Shalaby ◽  
Adel Mohamed Aboregela ◽  
Mohamed Ali Alabiad ◽  
Dina Fouad El Shaer
Keyword(s):  
Adrenal Cortex ◽  
Adult Male ◽  
Smooth Endoplasmic Reticulum ◽  
Dehydroepiandrosterone Sulfate ◽  
Male Rats ◽  
Male Rat ◽  
Control Group ◽  
Biochemical Alterations ◽  
Adult Male Rat

AbstractTramadol is a centrally acting analgesic drug, used for the management of moderate to severe pain in a variety of diseases. The long-term use of tramadol can induce endocrinopathy. This study aimed to evaluate the effect of tramadol dependence on the adrenal cortex and the effect of its withdrawal. Thirty adult male rats were divided into three experimental groups: the control group, the tramadol-dependent group that received increasing therapeutic doses of tramadol orally for 1 month, and the recovery group that received tramadol in a dose and duration similar to the previous group followed by a withdrawal period for another month. Specimens from the adrenal cortex were processed for histological, immunohistochemical, enzyme assay, and quantitative real-time PCR (RT-qPCR) studies. Tramadol induced a significant increase in malondialdehyde level and a significant decrease in the levels of glutathione peroxidase and superoxide dismutase. A significant decrease in the levels of adrenocorticotrophic hormones, aldosterone, cortisol, corticosterone, and dehydroepiandrosterone sulfate was also detected. Severe histopathological changes in the adrenal cortex were demonstrated in the form of disturbed architecture, swollen cells, and shrunken cells with pyknotic nuclei. Inflammatory cellular infiltration and variable-sized homogenized areas were also detected. A significant increase in P53 and Bax immunoreaction was detected and confirmed by RT-qPCR. The ultrastructural examination showed irregular, shrunken adrenocorticocytes with dense nuclei. Dilated smooth endoplasmic reticulum, mitochondria with disrupted cristae, and numerous coalesced lipid droplets were also demonstrated. All these changes started to return to normal after the withdrawal of tramadol. Thus, it was confirmed that the long-term use of tramadol can induce severe adrenal changes with subsequent insufficiency.

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