STUDIES ON THE BIOSYNTHESIS OF TESTOSTERONE IN THE RAT

1971 ◽  
Vol 68 (3) ◽  
pp. 614-624 ◽  
Author(s):  
Z. Kniewald ◽  
M. Zanisi ◽  
L. Martini
Keyword(s):  
Adrenal Gland ◽  
Sharp Decrease ◽  
Plasma Corticosterone ◽  
Male Rats ◽  
Plasma Testosterone ◽  
Normal Male ◽  
Sprague Dawley ◽  
Unilateral Adrenalectomy ◽  
Sprague Dawley Rats ◽  
Chromatographic Procedure

ABSTRACT Plasma levels of testosterone have been measured in adult male Sprague-Dawley rats using a gas-chromatographic procedure. Immediately after castration, the concentrations of testosterone in the plasma increase to reach a maximum one hour after orchidectomy; after this time a progressive decrease in plasma testosterone is observed. The concentration of testosterone then returns to levels close to those found before the operation two hours after castration; four hours after orchidectomy plasma testosterone begins to decrease to values lower than in the intact controls. Adrenalectomized animals with their testes in situ show a sharp decrease in plasma testosterone which begins immediately after the operation; the plasma testosterone reaches levels significantly lower than those in the intact control one hour after adrenalectomy; a greater decrease is observed four hours after the operation. Twenty-four hours after unilateral adrenalectomy the remaining gland significantly increases in weight; at this time, the plasma corticosterone and plasma testosterone levels of unilaterally adrenalectomized rats are normal. These results are interpreted as indicating that the adrenal gland of normal male rats is capable of producing testosterone, and that the synthesis of testosterone at the adrenal level is increased immediately after castration. Moreover it is suggested that the adrenal gland also contributes to the biosynthesis of testosterone in an indirect fashion, i. e. by providing the testes with an essential precursor. It has been tentatively proposed that progesterone might be such a precursor.

scholarly journals Effects of repeated doses and continuous infusions of the growth hormone-releasing peptide hexarelin in conscious male rats

1998 ◽  
Vol 158 (3) ◽  
pp. 367-375 ◽  
Author(s):  
LK Conley ◽  
RC Gaillard ◽  
A Giustina ◽  
RS Brogan ◽  
WB Wehrenberg
Keyword(s):  
Adult Male ◽  
Plasma Corticosterone ◽  
Male Rats ◽  
Continuous Exposure ◽  
Sprague Dawley ◽  
Treatment Groups ◽  
Sprague Dawley Rats ◽  
Repeated Doses ◽  
The Mean ◽  
Plasma Gh

We have previously shown that hexarelin, a novel GH-releasing peptide (GHRP), is able to elicit GH release when administered i.v., s.c. or by mouth and that it is a more potent GH secretagogue than GHRP-6. In the current study, we investigated the effects of hexarelin administered as repeated doses at 2 h intervals or as a continuous 6, 30 or 174 h infusion to conscious male rats. In the first experiment, adult male Sprague-Dawley rats were prepared with dual indwelling jugular catheters. On the day of experimentation, these animals received three 25 micrograms/kg i.v. boluses of hexarelin at 2 h intervals with blood sampling at 5, 10, 15, 30, 60, 90 and 120 min after each dose. The mean peak GH response and the mean area under the GH response curve (AUC) for the 30 min after each administration were calculated and are reported as the mean +/- S.E.M. For both the peak and AUC results there was a significant (P < 0.05) difference in the GH response noted between the first (peak 301 +/- 37 ng/ml; AUC 5585 +/- 700 ng/ml per 30 min) and second (peak 149 +/- 47 ng/ml; AUC 3056 +/- 908 ng/ml per 30 min) injections of hexarelin, but not between the first and third (peak 214 +/- 49 ng/ml; AUC 3862 +/- 844 ng/ml per 30 min). In a second series of experiments, adult male Sprague-Dawley rats received continuous infusions (100 micrograms/h) of hexarelin or saline (1 ml/h) for 6, 30 or 174 h. Blood samples were collected every 20 min for the duration of the 6 h infusion and for the last 6 h of the two longer hexarelin infusions. Plasma GH concentrations peaked within 40 min of the initiation of infusion, but soon returned to basal levels. Mean plasma GH concentrations did not differ between any of the treatment groups, nor did any of the parameters of pulsatile hormone release analyzed. No significant differences in plasma corticosterone concentrations were noted between any of the treatment groups. On the other hand, while neither the 6 h (941 +/- 70 ng/ml) nor the 30 h (954 +/- 70 ng/ml) hexarelin infusions resulted in a significant increase in the plasma IGF-I concentrations over those noted in the saline controls (935 +/- 65 ng/ml), a 174 h hexarelin infusion did elicit a significant increase (1289 +/- 42 ng/ml; P < 0.05). Thus it appears that, while continuous exposure to hexarelin does not disrupt normal GH cycling, it may (after up to 174 h of exposure) alter other components of the growth axis. In addition, since the character of pulsatile GH release remained unaltered in response to the hexarelin infusion, it appears that this GHRP may not act by suppression of functional somatostatin tone as has been suggested previously.

Dose Dependent Degeneration of Leydig Cells Following Kisspeptin-10 Administration: An Ultrastructural Study

2021 ◽  
Vol 28 ◽  
Author(s):  
Faiqah Ramzan ◽  
Irfan Zia Qureshi ◽  
Muhammad Haris Ramzan
Keyword(s):  
Leydig Cells ◽  
Plasma Concentrations ◽  
Physiological Saline ◽  
Testicular Tissue ◽  
Male Rats ◽  
Ultrastructural Changes ◽  
Plasma Testosterone ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Dose Dependent

Background: The discovery of kisspeptin signaling as a key regulator of gonadotropin releasing hormone (GnRH) secretion from the hypothalamus enhanced our understanding of the neuroendocrine regulation of mammalian reproduction. Effects of central and peripheral administration of kisspeptin on plasma gonadotropins, testosterone and spermatogenesis are studied in detail. Objective: The present study was conducted to check the ultrastructure of Leydig cells in prepubertal male rats in response to the administration of a range of kisspeptin doses. Method: To this end, we administered a range of kisspeptin-10 doses (1µg, 1ηg and 10ρg) intraperitoneally, to prepubertal male Sprague-Dawley rats (PND 35) twice daily after every 12 hours. Control rats were injected with physiological saline in parallel. Results: At the end of the treatment, plasma concentrations of testosterone was measured by competitive binding radioimmunoassay and small pieces of rat testicular tissue were processed for electron microscopy to examine the ultrastructure of Leydig cells. Plasma testosterone concentration was reduced significantly at 1ηg (P<0.05) and 1μg (P<0.01) doses as compared to control. Distinct ultrastructural changes categorized as dilatation of cytoplasmic organelles, irregular shaped nuclei with nuclear membrane invaginations, reduced nuclear sizes, degeneration and vacuolation were observed in the kisspeptin-10 treated Leydig cells as compared to control. Quantification of the data showed reduced Leydig cell indices and hyperplasia of the interstitial cells. Conclusion: It is concluded that chronic intermittent administration of kisspeptin-10 has a dose dependent degenerative effect on the plasma testosterone levels and Leydig cells ultrastructure in prepubertal male rats.

scholarly journals Antidepressant-Like Effect of Lipid Extract ofChanna striatusin Postpartum Model of Depression in Rats

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Mohamed Saleem Abdul Shukkoor ◽  
Mohamad Taufik Hidayat Bin Baharuldin ◽  
Abdul Manan Mat Jais ◽  
Mohamad Aris Mohamad Moklas ◽  
Sharida Fakurazi ◽  
...  
Keyword(s):  
Postpartum Period ◽  
Estradiol Benzoate ◽  
Plasma Corticosterone ◽  
Positive Control ◽  
Lipid Extract ◽  
High Dose ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Malay Population ◽  
Swimming Test

Postpartum depression affects 15% of women.Channa striatus, a freshwater fish, is consumed in local Malay population as a rejuvenating diet during postpartum period. This study evaluated the antidepressant-like effect of lipid extract ofC. striatusfillet and its mechanism of action in female Sprague-Dawley rats in postpartum model of depression. The rats were ovariectomized and treated with high dose of progesterone and estradiol benzoate for 23 days to have hormone-simulated pregnancy. The day 24 and afterwards were considered as the postpartum period. During the postpartum period, lipid extract was administered at 125, 250, and 500 mg/kg through intraperitoneal route for 15 days. Fluoxetine (10 mg/kg) was used as the positive control. On postpartum day 15, the animals were tested in forced swimming test (FST) and open field test (OFT) followed by biochemical analysis. Withdrawal of hormone administration during the postpartum period induced depressive-like behavior in FST. Administration of lipid extract reversed that depressive-like behavior at 125, 250, and 500 mg/kg in FST. In OFT, it decreased the exploratory activity. The mechanism of the antidepressant-like effect may be mediated through the decrease in plasma corticosterone, increase in plasma oxytocin, and decrease in nuclear factor-kappa B in prefrontal cortex of rats.

scholarly journals Erythropoietin Produces a Dual Effect on Carotid Body Chemoreception in Male Rats

2021 ◽  
Vol 12 ◽  
Author(s):  
Christian Arias-Reyes ◽  
Sofien Laouafa ◽  
Natalia Zubieta-DeUrioste ◽  
Vincent Joseph ◽  
Aida Bairam ◽  
...  
Keyword(s):  
Carotid Body ◽  
No Synthase ◽  
Male Rats ◽  
High Dose ◽  
No Production ◽  
Sprague Dawley ◽  
En Bloc ◽  
No Synthase Inhibitor ◽  
Sprague Dawley Rats ◽  
Synthase Inhibitor

Erythropoietin (EPO) regulates respiration under conditions of normoxia and hypoxia through interaction with the respiratory centers of the brainstem. Here we investigate the dose-dependent impact of EPO in the CB response to hypoxia and hypercapnia. We show, in isolated “en bloc” carotid body (CB) preparations containing the carotid sinus nerve (CSN) from adult male Sprague Dawley rats, that EPO acts as a stimulator of CSN activity in response to hypoxia at concentrations below 0.5 IU/ml. Under hypercapnic conditions, EPO did not influence the CSN response. EPO concentrations above 0.5 IU/ml decreased the response of the CSN to both hypoxia and hypercapnia, reaching complete inhibition at 2 IU/ml. The inhibitory action of high-dose EPO on the CSN activity might result from an increase in nitric oxide (NO) production. Accordingly, CB preparations were incubated with 2 IU/ml EPO and the unspecific NO synthase inhibitor (L-NAME), or the neuronal-specific NO synthase inhibitor (7NI). Both NO inhibitors fully restored the CSN activity in response to hypoxia and hypercapnia in presence of EPO. Our results show that EPO activates the CB response to hypoxia when its concentration does not exceed the threshold at which NO inhibitors masks EPO’s action.

Effects of androgens on bioactivity and immunoreactivity of pituitary FSH in GnRH antagonist-treated male rats

1990 ◽  
Vol 122 (2) ◽  
pp. 168-174 ◽  
Author(s):  
Om P. Sharma ◽  
Shafiq A. Khan ◽  
Gerhard F. Weinbauer ◽  
Mohammed Arslan ◽  
Eberhard Nieschlag
Keyword(s):  
Isoelectric Focusing ◽  
Gnrh Antagonist ◽  
Molecular Composition ◽  
Male Rats ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Combined Administration ◽  
Ph Range ◽  
Fsh Bioactivity

Abstract The effects of androgens on the bioactivity and molecular composition of pituitary FSH were examined in intact and GnRH antagonist-suppressed male rats. Eight groups of adult Sprague-Dawley rats were subjected to the following treatments: antagonist (75 μg/day by osmotic minipumps; sc), testosterone-filled Silastic implants (3×5 cm, sc), dihydrotestosterone-filled Silastic implants (3×5 cm, sc), E2 benzoate (15 μg/day, sc), and combined administration of antagonist with either steroid for 3 weeks. At the end of the treatment period, pituitaries were dissected out and homogenised. FSH content was determined in the pituitary extracts by an in vitro bioassay and a radioimmunoassay. Individual pituitary extracts from rats treated with vehicle, testosterone and testosterone + antagonist were subjected to isoelectric-focusing on sucrose density gradients performed in the pH range from 3.5 to 7.0. Individual isoelectric-focusing fractions (100-120) were analysed for bioactive and immunoreactive FSH. Treatment with antagonist, E2 or antagonist + E2 caused a significant decrease in pituitary FSH, whereas testosterone and dihydrotesterone alone or in combination with antagonist prevented the decrease in pituitary FSH. The effects of all treatments on both bioactive and immunoreactive FSH were similar. Testosterone treatment not only maintained FSH synthesis but also altered the molecular composition of pituitary FSH. Following treatment with testosterone there was a shift of maximal FSH bioactivity to the more acidic pH range. On the other hand, less bioactivity was recovered than corresponding immunoreactivity in the higher pH region, resulting in significantly reduced ratios of bioactivity to immunoreactivity of FSH. No significant differences were found in the isoelectric-focusing profiles or bioactivity to immunoreactivity ratios of pituitary FSH in animals treated with testosterone alone or in combination with antagonist. The results demonstrate that testosterone not only maintained the synthesis of both bioactive and immunoreactive FSH in male rats, but also influences the molecular composition of pituitary FSH. These effects of testosterone on pituitary FSH appear not to be mediated through hypothalamic GnRH.

Repeated restraint stress upregulates rat sulfotransferase 1A1

2018 ◽  
Vol 30 (2) ◽  
pp. 265-273
Author(s):  
Rajiv Balyan ◽  
Ma Cai ◽  
Wenhong Zhao ◽  
Zhao Dai ◽  
Yujia Zhai ◽  
...  
Keyword(s):  
Restraint Stress ◽  
Biological Activities ◽  
Male Rats ◽  
Transcriptional Level ◽  
Sprague Dawley ◽  
Metabolizing Enzymes ◽  
Sprague Dawley Rats ◽  
Repeated Restraint Stress ◽  
Enhanced Expression ◽  
Hormone Homeostasis

Abstract BackgroundSulfotransferases (SULTs) are phase II drug-metabolizing enzymes. SULTs also regulate the biological activities of biological signaling molecules, such as various hormones, bile acids, and monoamine neurotransmitters; therefore, they play critical roles in the endocrine and nervous systems. People are subject to various kinds of physical, chemical, toxicological, physiological, and psychological stresses at one time or another. The study of the effects produced by stress may lead to finding novel remedies for many disease conditions. The effect of repeated restraint stress on rat SULT expression has not been studied. MethodsThis study involves the effect of repeated restraint stress on SULT1A1 expressions. Male Sprague-Dawley rats (n=4) were subjected to repeated restraint stress 2 h/day for 7 days. Protein and RNA expression of SULT1A1 were analyzed by western blot and quantitative real time reverse transcription polymerase chain reaction, respectively, in important tissues. ResultsWe observed that repeated restraint stress increased the expression of SULT1A1 in the liver, adrenal glands, cerebellum, hypothalamus, and cerebral cortex in male rats. Patterns of enhanced expression were observed at both mRNA and protein level, indicating that repeated restraint stress stimulates enzyme expression at the transcriptional level. ConclusionsChanges of SULT1A1 expression in important tissues caused by repeated restraint stress will have a significant effect on drug metabolism and xenobiotics detoxification. The significant changes in endocrine glands and brain sections may also cause disturbances in hormone homeostasis, therefore leading to disease conditions. This report provides clues for the understanding of the effect of stresses on health.

scholarly journals THE EFFECT OF SECANG EXTRACT (CAESALPINIA SAPPAN LINN) ON THE WEIGHT AND HISTOLOGY APPEARANCE OF WHITE MALE RATS’ HEARTS INDUCED BY ISOPROTERENOL

2017 ◽  
Vol 9 ◽  
pp. 59
Author(s):  
Kristiana Nugraheni ◽  
Fadlina Chany Saputri
Keyword(s):  
Myocardial Infarction ◽  
Body Weight ◽  
White Male ◽  
Negative Control ◽  
Male Rats ◽  
Heart Cells ◽  
Sprague Dawley ◽  
Macroscopic Appearance ◽  
Caesalpinia Sappan ◽  
Sprague Dawley Rats

Objective: This study was conducted to determine the cardioprotective effect of secang extract on the heart cells of rats who suffered from myocardialinfarction induced by isoproterenol.Materials and Methods: Sprague Dawley rats were divided into six groups: Normal control, negative control, control extract (200 mg/kg), and threedifferent dose extract groups (50, 100, and 200 mg/kg body weight) that were given treatment for 30 days, and then, induced with isoproterenol.Observations were made for changes in the macroscopic appearance, cardiac weight, and histology of the cardiac organ.Results: The results showed a decrease in the incidence of myocardial infarction in rats given secang extract. The infarction area decreased withincreasing doses of extract. The weight of the heart in the control extract group was smaller than in the negative control group.Conclusions: Damage to heart cells, seen in the microscope, decreased with increasing doses.

scholarly journals Calorie Restriction Modulates Reproductive Development and Energy Balance in Pre-Pubertal Male Rats

Nutrients ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1993 ◽  
Author(s):  
Guilherme Rizzoto ◽  
Deepa Sekhar ◽  
Jacob C. Thundathil ◽  
Prasanth K. Chelikani ◽  
John P. Kastelic
Keyword(s):  
Body Composition ◽  
Energy Balance ◽  
Reproductive Development ◽  
Negative Energy ◽  
Male Rats ◽  
Plasma Testosterone ◽  
Feed Restriction ◽  
Testis Weight ◽  
Sprague Dawley ◽  
Ad Libitum

The objective was to determine effects of feed restriction and refeeding on reproductive development and energy balance in pre-pubertal male rats. Sprague Dawley rats (n = 32, 24 days old, ~65 g), were randomly allocated into four treatments (n = 8/treatment): (1) Control (CON, ad libitum feed; (2) Mild Restriction (MR, rats fed 75% of CON consumption); (3) Profound Restriction (PR, 50% of CON consumption); or (4) Refeeding (RF, 50% restriction for 14 days, and then ad libitum for 7 days). Feed restriction delayed reproductive development and decreased energy balance and tissue accretion, with degree of reproductive and metabolic dysfunctions related to restriction severity. In RF rats, refeeding largely restored testis weight, sperm production (per gram and total), plasma IGF-1, leptin and insulin concentrations and energy expenditure, although body composition did not completely recover. On Day 50, more CON and RF rats than PR rats were pubertal (5/6, 4/5 and 1/6, respectively; plasma testosterone >1 ng/mL) with the MR group (4/6) not different. Our hypothesis was supported: nutrient restriction of pre-pubertal rats delayed reproductive development, induced negative energy balance and decreased metabolic hormone concentrations (commensurate with restriction), whereas short-term refeeding after profound restriction largely restored reproductive end points and plasma hormone concentrations, but not body composition.

Sexual dimorphism in vasopressin-induced contraction of rat aorta

1991 ◽  
Vol 260 (2) ◽  
pp. H453-H458 ◽  
Author(s):  
J. N. Stallone ◽  
J. T. Crofton ◽  
L. Share
Keyword(s):  
Estrous Cycle ◽  
Vascular Reactivity ◽  
Rat Aorta ◽  
Isometric Tension ◽  
Female Rats ◽  
Male Rats ◽  
Maximal Response ◽  
Sprague Dawley ◽  
Tension Development ◽  
Sprague Dawley Rats

Previously, we reported that, in the rat, pressor responsiveness to vasopressin (VP) is higher in males than in females during most phases of the estrous cycle. To explore the role of the vasculature in this phenomenon, we examined vascular reactivity to VP in thoracic aortas of male rats and female rats during each phase of the estrous cycle. Aortic rings were prepared from age-matched male and female Sprague-Dawley rats and mounted for isometric tension recording. Maximal response of female aortas to VP (4,246 +/- 163 mg/mg ring dry wt) was more than twice (P less than 0.001) that of male aortas (1,877 +/- 215 mg/mg ring wt). Sensitivity of female aortas to VP was substantially higher (P less than 0.001) than that of male aortas (EC50: 10.9 +/- 0.7 vs. 19.0 +/- 1.6 nM, respectively). Maximal rate of tension development (dT/dtmax) during contraction with VP was nearly twofold higher (P less than 0.01) in female aortas (536 +/- 23 mg/min) than in male aortas (300 +/- 19 mg/min). Maximal response, sensitivity, and dT/dtmax of female aortas did not vary significantly during the estrous cycle. Maximal response of female aortas to phenylephrine (PE; 1,251 +/- 93 mg/mg ring wt) was half that (P less than 0.001) of male aortas (2,546 +/- 194 mg/mg ring wt); sensitivity to PE did not differ significantly (EC50: 0.33 +/- 0.02 vs. 0.38 +/- 0.06 microM, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

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