THE PITUITARY RESPONSE TO EXOGENOUS LUTEINIZING HORMONE RELEASING FACTOR IN STEROID-TREATED GONADECTOMIZED RATS

1976 ◽  
Vol 69 (2) ◽  
pp. 255-262 ◽  
Author(s):  
M. S. AIYER ◽  
M. C. SOOD ◽  
K. BROWN-GRANT
Keyword(s):  
Plasma Concentrations ◽  
Female Rats ◽  
Male Rats ◽  
Postnatal Life ◽  
Marked Rise ◽  
Male And Female ◽  
Male And Female Rats ◽  
Gonadotrophin Secretion ◽  
Males And Females ◽  
Concentration Curves

SUMMARY Rats gonadectomized 1–2 months previously were anaesthetized with sodium pentobarbitone and 50 ng/100 g body weight of a synthetic decapeptide gonadotrophin releasing factor (LH-RF) injected intravenously. Plasma concentrations of LH and FSH were determined by radioimmunoassay in samples taken before and at intervals up to 60 min after the injection of LH-RF. The pituitary response was evaluated by determining the maximal increment in plasma gonadotrophin concentrations and by estimating the area under the plasma gonadotrophin concentration curves. In both males and females the pituitary response was increased in animals given 20 μg oestradiol benzoate 3 days earlier. Progesterone (2·5 mg) had no effect on the response measured 4 h later in oil-treated rats, male or female. In oestrogen-primed rats progesterone administration produced a significantly increased response in females that was not seen if sodium pentobarbitone was given at the time of progesterone injection. In oestrogen-primed males progesterone produced some increase in sensitivity but less than was seen in females. Both in males and in females that had received androgen on day 4 of postnatal life sodium, pentobarbitone had no effect on the responses of oestrogen plus progesterone-treated rats to LH-RF. When two injections of LH-RF were given 60 min apart, the second response was greater than the first in animals, both male and female, that had been primed with oestrogen. The second response was no greater than the first in oil-treated females. The results suggest that oestrogen can increase pituitary sensitivity to LH-RF in both male and female rats and that LH-RF itself can increase pituitary sensitivity to a second injection of LH-RF in both male and female rats if they have received oestrogen. It is suggested that the differences between the pituitary responses of females and males after oestrogen plus progesterone treatment and the major differences in gonadotrophin secretion reported previously (Brown-Grant, 1974) may be accounted for on the basis of there being a relatively slight increase in endogenous LH-RF secretion with a consequent marked rise in pituitary responsiveness in female but not in male rats.

Sex- and age-dependent differences in the hormone and drinking responses to water deprivation

2020 ◽  
Vol 318 (3) ◽  
pp. R567-R578 ◽  
Author(s):  
Susana Quirós Cognuck ◽  
Wagner L. Reis ◽  
Marcia S. Silva ◽  
Gislaine Almeida-Pereira ◽  
Lucas K. Debarba ◽  
...  
Keyword(s):  
Water Deprivation ◽  
Plasma Concentrations ◽  
Female Rats ◽  
Male Rats ◽  
Ang Ii ◽  
Adult Males ◽  
Adaptive Responses ◽  
Male And Female ◽  
Male And Female Rats ◽  
Female Wistar Rats

Maintenance of the volume and osmolality of body fluids is important, and the adaptive responses recruited to protect against osmotic stress are crucial for survival. The objective of this work was to compare the responses that occur in aging male and female rats during water deprivation. For this purpose, groups of male and female Wistar rats aged 3 mo (adults) or 18 mo (old) were submitted to water deprivation (WD) for 48 h. The water and sodium (0.15 M NaCl) intake, plasma concentrations of oxytocin (OT), arginine vasopressin (AVP), corticosterone (CORT), atrial natriuretic peptide (ANP), and angiotensin II (ANG II) were determined in hydrated and water-deprived animals. In response to WD, old male and female rats drank less water and saline than adults, and both adult and old females drank more water and saline than respective males. Dehydrated old animals displayed lower ANG II plasma concentration and CORT response compared with the respective normohydrated rats. Dehydrated adult males had higher plasma ANP and AVP as well as lower CORT concentrations than dehydrated adult females. Moreover, plasma OT and CORT levels of old female rats were higher than those in the dehydrated old male rats. Relative expression of ANG II type 1 receptor mRNA was decreased in the subfornical organ of adult and old male rats as well as adult female rats in response to WD. In conclusion, the study elucidated the effect of sex and age on responses induced by WD, altering the degree of dehydration induced by 48 h of WD.

Growth hormone responses to multiple injections of a fragment of human growth hormone-releasing factor in conscious male and female rats

1985 ◽  
Vol 106 (3) ◽  
pp. 281-289 ◽  
Author(s):  
R. G. Clark ◽  
I. C. A. F. Robinson
Keyword(s):  
Growth Hormone ◽  
Human Growth ◽  
Female Rats ◽  
Male Rats ◽  
Normal Male ◽  
Male And Female ◽  
Gh Secretion ◽  
Male And Female Rats ◽  
Hormone Responses ◽  
Males And Females

ABSTRACT The GH responses to single i.v. injections of GH-releasing factor (GRF) in conscious male rats are highly variable. Although normal male rats show a pulsatile secretory pattern of GH with pulses occurring at intervals of 3–3·5 h, the peaks occur at different times in individual animals. We have compared the GH responses of young conscious male and female rats to multiple i.v. injections of 1 μg human (h) GRF1-29NH2. The peak GH responses occurred 3–5 min after hGRF1-29NH2 injection and were lower in female than in male rats. Both males and females responded uniformly to hGRF1-29NH2 injections given 180 min apart and the GH responses became entrained with no endogenous GH pulsing. Female rats produced consistent GH peaks in response to hGRF1-29NH2 injections at 90-min intervals, whereas male rats responded only to alternate injections, so that GH peaks occurred only every 180 min despite giving GRF every 90 min. When the frequency of hGRF1-29NH2 administration was increased to once every 40 min female rats again responded consistently to each injection. Male rats responded intermittently, being able to respond to two injections 40 min apart, after which they became refractory to hGRF1-29NH2. This cycle of varying sensitivity to GRF in male rats probably underlies their 3-hourly endogenous GH secretory rhythm. Female rats can respond uniformly to repeated GRF injections, consistent with their more continuous pattern of endogenous GH secretion. Introducing a pulse of 10 μg rat GH into a series of hGRF1-29NH2 injections did not induce refractoriness to hGRF1-29NH2, suggesting that GH does not itself desensitize the pituitary to GRF. Whether the different patterns of GH secretion in males and females result from different patterns of GRF and/or somatostatin secretion remains to be determined. J. Endocr. (1985) 106, 281–289

Gonad-gonadotrope interactions: plasma gonadotrophin levels and tumour induction in long-term castrated rats

1981 ◽  
Vol 97 (2) ◽  
pp. 181-185 ◽  
Author(s):  
Daniel M. Linkie ◽  
Jacob Furth ◽  
Diane Kourelakos
Keyword(s):  
Immunohistochemical Localization ◽  
Female Rats ◽  
Male And Female ◽  
Tumour Induction ◽  
Male And Female Rats ◽  
Specific Radioimmunoassay ◽  
Gonadotrophin Secretion ◽  
Males And Females

Abstract. The patterns of gonadotrophin secretion in intact controls and in male and female rats castrated for up to 36 months were established utilizing specific radioimmunoassay methods. Plasma LH increased 14– 16-fold and FSH rose 4–8-fold in rats of either sex in the first 30 days following gonadectomy. The subsequent 30 day interval showed an additional 76% increase of LH in both sexes and increases in FSH of 32 and 61% in males and females, respectively. These levels were maintained for an additional 34 months. The number of hypophyseal gonadotrophin containing cells, studied by immunohistochemical localization techniques, increased following gonad removal in a pattern similar to that for the circulating hormones. Development of gonadotrophin secreting tumours did not correlate with plasma gonadotrophin concentrations which suggests that the gonadotropes are uniquely resistant to tumourogenesis unlike mammotropes, thyrotropes, and corticotropes.

scholarly journals Does the antidepressant-like effect of mirtazapine and venlafaxine differ between male and female rats?

Salud Mental ◽  
2020 ◽  
Vol 43 (1) ◽  
pp. 3-9
Author(s):  
Adriana Álvarez Silva ◽  
Alonso Fernández-Guasti
Keyword(s):  
Forced Swim Test ◽  
Treatment Options ◽  
Female Rats ◽  
Male Rats ◽  
Male And Female ◽  
Swim Test ◽  
Male And Female Rats ◽  
Males And Females ◽  
New Treatment ◽  
Global Health Problem

Introduction. Depression is a global health problem with nearly 350 million people affected, mainly women. However, nowadays a rising amount of men are being diagnosed. This makes necessary the screening of new treatment options that are effective in women as well as in men. Objective. To analyze if the administration of mirtazapine and venlafaxine to male and female rats shows a sex-related antidepressant-like effect, and the possible associated neurochemical mechanisms. Method. Mirtazapine (40 mg/kg) or venlafaxine (60 mg/kg) were administered subchronically to young adult male and female (ovariectomized and steroid-primed) rats, and their antidepressant-like effects were evaluated using the forced swim test (FST). The active behaviors, swimming and climbing, were also analyzed. Results. a) mirtazapine and venlafaxine reduced immobility in the FST in males and females; b) both antidepressants increased climbing and swimming in male rats; c) in female rats, mirtazapine and venlafaxine only increased swimming. Discussion and conclusion. In males, the effects of mirtazapine and venlafaxine seem to be produced by the activation of the serotonergic and noradrenergic systems. Conversely, estradiol might be modulating the mechanisms of action of both antidepressants in females producing only an increased swimming and suggesting the participation of the serotonergic system.

Sexual dimorphism in the growth response of entire and gonadectomized rats to clenbuterol

1995 ◽  
Vol 268 (6) ◽  
pp. E1077-E1082 ◽  
Author(s):  
M. N. Sillence ◽  
M. M. Reich ◽  
B. C. Thomson
Keyword(s):  
Gender Difference ◽  
Control Diet ◽  
Plasma Concentrations ◽  
Female Rats ◽  
Male Rats ◽  
Muscle Weight ◽  
Relative Contribution ◽  
Male And Female Rats ◽  
Males And Females ◽  
Beta 2

This study compared the anabolic effects of clenbuterol in male and female rats and determined the relative contribution of testicular and ovarian hormones to any observed gender difference. Seventy-two 12-wk-old rats were used in a 2 x 2 x 2 factorial design in which animals were either male or female, entire or gonadectomized at 3 wk of age, and fed either a control diet or a diet containing 4 mg clenbuterol/kg feed for 8 days. Compared with entire male rats, entire females gained 64% less weight, had lighter carcasses (-36%) and gastrocnemius muscles (-62%), and had higher plasma concentrations of the catabolic hormone corticosterone (P < 0.05). Castration had a negative effect on growth in male rats, and ovariectomy had a positive effect in females, but there was still a gender difference in body weight between gonadectomized males and females, which amounted to 34% of the gender difference observed in intact rats. The density of beta 2-adrenoceptors in skeletal muscle was not different between males and females, nor was it affected by gonadectomy. Clenbuterol increased both weight gain and gastrocnemius muscle weight, with the latter response in entire and castrated male rats (+ 1.31 and + 1.17 g) being more than double that seen in entire and ovariectomized females (+ 0.58 and + 0.55 g). The downregulation response of beta 2-adrenoceptors in this muscle was remarkably consistent in all treated groups (-50% to -53%).(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics and Efficacy of a Long-lasting, Highly Concentrated Buprenorphine Solution in Rats

2021 ◽  
Author(s):  
Elizabeth R Houston ◽  
Sarah M Tan ◽  
Samantha M Thomas ◽  
Ulana L Stasula ◽  
Mollie K Burton ◽  
...  
Keyword(s):  
Plasma Levels ◽  
Opioid Analgesic ◽  
Plasma Concentrations ◽  
Pain Tolerance ◽  
Female Rats ◽  
Male Rats ◽  
Suitable Alternative ◽  
Male And Female ◽  
Male And Female Rats ◽  
Drug Concentrations

Buprenorphine (Bup) is an opioid analgesic that is commonly used in laboratory rodents to provide postoperative analgesia. However, dosing every 4 to 6 h is necessary to maintain an analgesic plasma concentration of the drug. A long lasting,highly concentrated veterinary formulation of Bup (LHC-Bup) has been used to provide prolonged analgesia in cats and nonhuman primates. In the current study, we evaluated the duration of efficacy of LHC-Bup to determine if this formulation would provide a similarly prolonged analgesia in rats. Drug concentrations were measured after subcutaneous injectionof 0.5 mg/kg LHC-Bup in both male and female rats. Plasma levels were measured at 0.25, 0.5, 1, 2, 4, 8, 12, 24, 36, 48, and72 h. Male and female rats had peak plasma levels of LHC-Bup at 90 ng/and 34 ng/mL, respectively, at 15 min after administration, with a steady decrease by 24 h to 0.7 ng/mL in males and 1.3 ng/mL in females. Mechanical pain tolerance wasevaluated after LHC-Bup administration using a Randall-Selitto analgesiometer to assess paw withdrawal. Male rats had a significantly longer paw withdrawal time for up to 12 h after administration, and females had longer paw withdrawal timesfor up to 24 h. An experimental laparotomy model was then used to assess the clinical efficacy of LHC-Bup at 0.5 mg/kg. LHC-Bup treatment was associated with a greater total distance traveled, reduced time to retrieve a food treat, and reduced grooming from 3 to 12 h after surgery as compared with saline controls. Groups receiving LHC-Bup showed coprophagy whereas other rats did not. These results suggest that administering LHC-Bup at 0.5 mg/kg provides therapeutic plasma concentrations for 12 to 24 h after administration and analgesic efficacy for at least 12 h after dosing. As such, LHC-Bup is a suitable alternative to Bup-HCl.

Effects of the new prolactin-producing tumour 7315b on gonadotrophin secretion in adult male and female rats

1989 ◽  
Vol 120 (2) ◽  
pp. 261-268 ◽  
Author(s):  
A. Kooy ◽  
R. F. A. Weber ◽  
M. P. Ooms ◽  
J. T. M. Vreeburg
Keyword(s):  
Serum Levels ◽  
Female Rats ◽  
Male Rats ◽  
Suitable Model ◽  
Intact Male ◽  
Adult Rats ◽  
Male And Female ◽  
Male And Female Rats ◽  
Serum Lh ◽  
Gonadotrophin Secretion

ABSTRACT The effects of the transplantable purely prolactin-secreting tumour 7315b on serum gonadotrophins were studied in adult rats. Possible contributions of the adrenals to the tumour-induced inhibition of serum LH and FSH were evaluated. The suppressive actions of tumour 7315b on serum gonadotrophins in gonadectomized plus adrenalectomized male and female rats were compared. Within 4 weeks after inoculation of tumour 7315b in intact male rats very high levels of prolactin and decreased serum levels of gonadotrophins and testosterone were recorded. At autopsy reduced weights of testes and accessory sex organs and slightly increased adrenal weights were found. In addition, in animals treated with a small testosterone-filled capsule after castration, tumour 7315b reduced serum concentrations of LH and FSH. Adrenalectomy did not prevent this suppressive action of the tumour on the post-castration rise of serum gonadotrophins. Suppression of serum gonadotrophins during hyperprolactinaemia was greater in gonadectomized plus adrenalectomized female rats than in male rats, indicating that the degree of the tumour-induced suppression of LH and FSH after castration is determined to a large extent by the sex of the animal. The purely prolactin-secreting tumour 7315b has therefore been shown to be a suitable model for studying the effects of severe hyperprolactinaemia on the pituitary-gonadal axis in rats. Journal of Endocrinology (1989) 120, 261–268

INDUCTION OF GOITRE BY PTU OR KClO4 IN MALE AND FEMALE RATS. EFFECT OF GONADECTOMY

1973 ◽  
Vol 74 (1) ◽  
pp. 88-104 ◽  
Author(s):  
T. Jolín ◽  
M. J. Tarin ◽  
M. D. Garcia
Keyword(s):  
Iodine Content ◽  
High Plasma ◽  
Disc Electrophoresis ◽  
Female Rats ◽  
Male Rats ◽  
Adult Rats ◽  
Male And Female ◽  
Glucose Levels ◽  
Male And Female Rats ◽  
Tsh Levels

ABSTRACT Male and female rats of varying ages were placad on a low iodine diet (LID) plus KClO4 or 6-propyl-2-thiouracil (PTU) or on the same diet supplemented with I (control rats). Goitrogenesis was also induced with LID plus PTU in gonadectomized animals of both sexes. The weight of the control and goitrogen treated animals, and the weight and iodine content of their thyroids were determined, as well as the plasma PBI, TSH, insulin and glucose levels. The pituitary GH-like protein content was assessed by disc electrophoresis on polyacrylamide gels. If goitrogenesis was induced in young rats of both sexes starting with rats of the same age, body weight (B.W.) and pituitary growth hormone (GH) content, it was found that both the males and females developed goitres of the same size. On the contrary, when goitrogenesis was induced in adult animals, it was found that male rats, that had larger B.W. and pituitary GH content than age-paired females, developed larger goitres. However, both male and female rats were in a hypothyroid condition of comparable degree as judged by the thyroidal iodine content and the plasma PBI and TSH levels. When all the data on the PTU or KClO4-treated male and female rats of varying age and B.W. were considered together, it was observed that the weights of the thyroids increased proportionally to B.W. However, a difference in the slope of the regression of the thyroid weight over B.W. was found between male and female rats, due to the fact that adult male rats develop larger goitres than female animals. In addition, in the male rats treated with PTU, gonadectomy decreased the B.W., pituitary content of GH-like protein and, concomitantly, the size of the goitre decreased; an opposite effect was induced by ovariectomy on the female animals. However, when goitrogenesis was induced in weight-paired adult rats of both sexes, the male animals still developed larger goitres than the females. Among all the parameters studied here, the only ones which appeared to bear a consistent relationship with the size of the goitres in rats of different sexes, treated with a given goitrogen, were the rate of body growth and the amount of a pituitary GH-like protein found before the onset of the goitrogen treatment. Moreover, though the pituitary content of the GH-like protein decreased as a consequence of goitrogen treatment, it was still somewhat higher in male that in female animals. The present results suggest that GH may somehow be involved in the mechanism by which male and female rats on goitrogens develop goitres of different sizes, despite equally high plasma TSH levels.

GONADOTROPHIN PATTERNS IN MALE AND FEMALE RATS:

1968 ◽  
Vol 58 (4) ◽  
pp. 600-612 ◽  
Author(s):  
Robert Boyd ◽  
Donald C. Johnson
Keyword(s):  
Ascorbic Acid ◽  
Testosterone Propionate ◽  
Female Rats ◽  
Female Rat ◽  
Feedback Effects ◽  
Male And Female ◽  
Prostate Weight ◽  
Male And Female Rats ◽  
Males And Females ◽  
Normal Males

ABSTRACT The effects of various doses of testosterone propionate (TP) upon the release of luteinizing hormone (LH or ICSH) from the hypophysis of a gonadectomized male or female rat were compared. Prostate weight in hypophysectomized male parabiotic partners was used to evaluate the quantity of circulating LH. Hypophyseal LH was measured by the ovarian ascorbic acid depletion method. Males castrated when 45 days old secreted significantly more LH and had three times the amount of pituitary LH as ovariectomized females. Administration of 25 μg TP daily reduced the amount of LH in the plasma, and increased the amount in the pituitary gland, in both sexes. Treatment with 50 μg caused a further reduction in plasma LH in males, but not in females, while pituitary levels in both were equal to that of their respective controls. LH fell to the same low level in partners of males or females receiving 100 μg TP. When gonadectomized at 39 days, males and females had the same amount of plasma LH, but males had more stored hormone. Pituitary levels were unchanged from controls following treatment with 12.5, 25 or 50 μg TP daily, but plasma values dropped an equal amount in both sexes with the latter two doses. Androgenized males or females, gonadectomized when 39 days old, were very sensitive to the effects of TP and plasma LH was significantly reduced with 12.5 μg daily. Pituitary LH in androgenized males was higher than that of normal males but was reduced to normal by small amounts of TP. The amount of stored LH in androgenized females was not different from that of normal females and it was unchanged by any dose of TP tested. Results are consistent with the conclusion that the male hypothalamic-hypophyseal axis is at least as sensitive as the female axis to the negative feedback effects of TP. Androgenization increases the sensitivity to TP in both males and females.

scholarly journals Stem cell treatment improves post stroke neurological outcomes: a comparative study in male and female rats

2021 ◽  
pp. svn-2020-000834
Author(s):  
Koteswara Rao Nalamolu ◽  
Bharath Chelluboina ◽  
Casimir A Fornal ◽  
Siva Reddy Challa ◽  
David M Pinson ◽  
...  
Keyword(s):  
Stem Cells ◽  
Sex Differences ◽  
Motor Function ◽  
Infarct Volume ◽  
Female Rats ◽  
Human Umbilical Cord ◽  
Male And Female ◽  
Post Stroke ◽  
Male And Female Rats ◽  
Males And Females

Background and purposeThe therapeutic potential of different stem cells for ischaemic stroke treatment is intriguing and somewhat controversial. Recent results from our laboratory have demonstrated the potential benefits of human umbilical cord blood-derived mesenchymal stem cells (MSC) in a rodent stroke model. We hypothesised that MSC treatment would effectively promote the recovery of sensory and motor function in both males and females, despite any apparent sex differences in post stroke brain injury.MethodsTransient focal cerebral ischaemia was induced in adult Sprague-Dawley rats by occlusion of the middle cerebral artery. Following the procedure, male and female rats of the untreated group were euthanised 1 day after reperfusion and their brains were used to estimate the resulting infarct volume and tissue swelling. Additional groups of stroke-induced male and female rats were treated with MSC or vehicle and were subsequently subjected to a battery of standard neurological/neurobehavioral tests (Modified Neurological Severity Score assessment, adhesive tape removal, beam walk and rotarod). The tests were administered at regular intervals (at days 1, 3, 5, 7 and 14) after reperfusion to determine the time course of neurological and functional recovery after stroke.ResultsThe infarct volume and extent of swelling of the ischaemic brain were similar in males and females. Despite similar pathological stroke lesions, the clinical manifestations of stroke were more pronounced in males than females, as indicated by the neurological scores and other tests. MSC treatment significantly improved the recovery of sensory and motor function in both sexes, and it demonstrated efficacy in both moderate stroke (females) and severe stroke (males).ConclusionsDespite sex differences in the severity of post stroke outcomes, MSC treatment promoted the recovery of sensory and motor function in male and female rats, suggesting that it may be a promising treatment for stroke.

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