A COMPARISON OF CHANGES IN THE PERIPHERAL PLASMA CONCENTRATIONS OF LUTEINIZING HORMONE AND FOLLICLESTIMULATING HORMONE IN THE RAT

1975 ◽  
Vol 65 (3) ◽  
pp. 389-397 ◽  
Author(s):  
K. BROWN-GRANT ◽  
FENELLA GREIG
Keyword(s):  
Plasma Concentrations ◽  
Fold Increase ◽  
Early Response ◽  
Female Rats ◽  
Male Rats ◽  
Postnatal Life ◽  
Experimental Conditions ◽  
Releasing Factors ◽  
Secretion Rates ◽  
Sustained Increase

SUMMARY Plasma FSH concentrations in rats have been determined by radioimmunoassay under a variety of experimental conditions to see whether any evidence could be obtained of an acute divergence in LH and FSH secretion rates which would support the idea of separate, specific hypothalamic releasing factors for these two hormones. During the normal ovarian cycle and after the administration of progesterone to female rats on the morning of the day of pro-oestrus increased secretion of both LH and FSH began simultaneously but FSH concentrations were later maintained or increased slightly while LH concentrations were falling. During early pregnancy FSH concentrations were higher than at the corresponding stage of the cycle at a time when LH concentrations had been shown to be lower. Progesterone injected at the dioestrous stage of the cycle reduced both LH and FSH concentrations though the effect on LH was more marked. After ovariectomy at any stage of the oestrous cycle or on day 4 of pregnancy there was a rapid and significant increase in plasma FSH concentration which was quite different from the delayed increase in LH concentration observed in these animals. In contrast, the early increase in FSH concentration in male rats after castration was less than the increase in LH concentration. The final FSH concentration in castrated males was only about four times the basal level in contrast to the 10- to 15-fold increase in LH in males and both LH and FSH in females. Anovulatory adult females that had received 1·25 mg of testosterone propionate on day 4 of postnatal life showed the rapid and sustained increase in plasma FSH after ovariectomy that was seen in normal females. None of these results strongly support the idea that separate and specific hypothalamic releasing factors for LH or FSH are secreted in the rat although the differences in the early response to gonadectomy could be explained on this basis.

scholarly journals MICROBODIES IN EXPERIMENTALLY ALTERED CELLS

1967 ◽  
Vol 35 (1) ◽  
pp. 127-152 ◽  
Author(s):  
Donald Svoboda ◽  
Harold Grady ◽  
Daniel Azarnoff
Keyword(s):  
Female Rats ◽  
Male Rats ◽  
Hypolipidemic Effect ◽  
Kidney Cells ◽  
Experimental Conditions ◽  
Hypolipidemic Drug ◽  
Sufficient Cause ◽  
Monkey Liver ◽  
Liver And Kidney ◽  
Sustained Increase

A rapid and sustained increase in the number of microbodies in liver and kidney cells can be induced in male rats by ethyl chlorophenoxyisobutyrate (CPIB), a hypolipidemic drug. This phenomenon permits investigation of several aspects of microbody behavior in experimental conditions. Reversal experiments demonstrate that liver cells revert to normal between 2 and 3 weeks after withdrawal of CPIB and that one of the mechanisms for removal of excess microbodies is their incorporation into structures indistinguishable from lysosomes. In a state of rapid cell division, such as that present during liver regeneration, microbody proliferation apparently occupies a high biological priority. In necrotic or degenerating cells microbody structure remains relatively normal. The increase in microbodies induced by CPIB is inhibited by chloramphenicol. No increase in microbodies occurred in female rats or in chickens, guinea pigs, or rabbits at the dosage used (0.25% in diet). No changes in microbodies were seen in monkey liver. Catalase activity was generally parallel to the numerical response in microbodies. Additional observations suggest that the microbody response to CPIB is not related to hepatomegaly induced by this agent but may be related to the hypolipidemic effect of CPIB, though hypolipidemia per se is not a specific or sufficient cause of microbody proliferation.

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.

INFLUENCE OF THE REPRODUCTIVE STATE AT THE TIME OF OPERATION ON THE EARLY RESPONSE TO OVARIECTOMY IN THE RAT

1972 ◽  
Vol 53 (1) ◽  
pp. 47-57 ◽  
Author(s):  
C. M. TAPPER ◽  
F. NAFTOLIN ◽  
K. BROWN-GRANT
Keyword(s):  
Feedback System ◽  
Early Response ◽  
Female Rats ◽  
Male Rats ◽  
Specific Response ◽  
Gonadal Steroid ◽  
Reproductive State ◽  
Initial Rise ◽  
Male And Female Rats ◽  
Time Of Operation

SUMMARY The changes in plasma luteinizing hormone (LH) concentration during the first few days after ovariectomy in the rat differ according to the stage of the cycle at which the operation is performed. When carried out at oestrus there was no increase in LH concentration in the first 4 days. After operation at metoestrus the concentration was increased at 3 days but not earlier. Ovariectomy at dioestrus resulted in an immediate increase after 8 h, a subsequent fall, though not to basal levels, and a fairly steady rise thereafter. Ovariectomy at pro-oestrus produced a very large initial rise in plasma LH which probably represents an accelerated release of the ovulatory surge of LH rather than a specific response to ovariectomy. At 24 h after ovariectomy at pro-oestrus levels were below normal and did not increase again for a further 3 days. In contrast, male rats showed a rapid and sustained rise in plasma LH concentration after castration. It is suggested that the different patterns seen in the female may be related to the time that elapsed since the hypothalamo—pituitary system was exposed to high levels of circulating oestradiol. The changes in plasma LH concentration observed after ovariectomy in neonatally androgen-treated rats, rats in persistent oestrus due to exposure to constant light, and rats in early pregnancy are consistent with this hypothesis. Differing responses to the administration of sodium pentobarbitone between male and female rats even 21 days after gonadectomy suggest that there may also be differences in this negative feedback system between the two sexes that are independent of the nature of the gonadal steroid secreted.

Effects of trenbolone acetate and testosterone on growth and on plasma concentrations of corticosterone and ACTH in rats

1990 ◽  
Vol 126 (3) ◽  
pp. 461-466 ◽  
Author(s):  
M. N. Sillence ◽  
R. G. Rodway
Keyword(s):  
Weight Gain ◽  
Growth Response ◽  
Plasma Concentrations ◽  
Female Rats ◽  
Male Rats ◽  
Adrenal Weight ◽  
Trenbolone Acetate ◽  
Male And Female Rats ◽  
Age Related ◽  
Old Rats

ABSTRACT The effects of trenbolone acetate (TBA) on growth and on plasma concentrations of corticosterone were examined in male and female rats. At 5 weeks of age, rats were injected with TBA (0·8 mg/kg) dissolved in peanut oil, or with oil alone, daily for 10 days. In female rats, TBA caused an increase in weight gain (20–38%), a reduction in adrenal weight (19%) and a reduction in plasma concentrations of corticosterone (55%). In contrast, TBA-treated male rats showed no significant increase in weight gain, no significant change in adrenal weight and no reduction in plasma concentrations of corticosterone. The mechanism by which adrenal activity was suppressed in TBA-treated female rats was examined and the response compared with that to testosterone. Female rats (8 weeks old) were injected daily either with oil vehicle, TBA (0·8 mg/kg) or testosterone propionate (0·8 mg/kg). Testosterone increased weight gain (24%), but the growth response to TBA treatment was significantly greater (97%). A reduction in plasma concentrations of corticosterone (45%) was again observed in response to TBA. However, testosterone increased plasma concentrations of corticosterone (52%) above those of control values. Neither androgen affected plasma concentrations of ACTH. Finally, the effects of TBA were examined in 6-week-old female rats, to characterize further the apparent age-related increase in responsiveness. The growth response of 6-week-old rats (60–74%) was intermediate between that seen in 5- and 8-week-old animals. It is concluded that part of the anabolic activity of TBA may be related to a reduction in circulating concentrations of corticosterone. The effect of TBA on corticosterone concentrations differs from that of the natural androgen, testosterone, and does not appear to be mediated by a reduction in plasma concentrations of ACTH. Journal of Endocrinology (1990) 126, 461–466

Effects of Guanethidine and Related Compounds on Histamine Excretion

1972 ◽  
Vol 50 (6) ◽  
pp. 539-544 ◽  
Author(s):  
J. LeBlanc ◽  
J. Côté ◽  
F. Doré ◽  
S. Rousseau
Keyword(s):  
Peritoneal Fluid ◽  
Fold Increase ◽  
Female Rats ◽  
Male Rats ◽  
Daily Injection ◽  
Histamine Metabolism ◽  
Methyl Transferase ◽  
Single Intraperitoneal Injection ◽  
Urinary Histamine ◽  
Related Compounds

The basic nature of guanethidine and some of its effects suggested a possible action of this drug on histamine metabolism. A single intraperitoneal injection of guanethidine (10 mg/kg) in male rats was found to double the daily urinary excretion of free histamine; daily injection for three weeks caused a 10-fold increase. In male rats, guanethidine increased the number of mast cells in the peritoneal fluid and, in both peritoneal fluid and mesentery, caused a significant degranulation of these cells; this action was not observed in female rats. This finding may indicate that guanethidine blocks methylation of histamine by inhibiting imidazole methyl transferase since this enzyme is found in male but not in female rats. Bethanidine and reserpine had no effect on histamine excretion. Imidazole was found to be even more potent than guanethidine in causing an increase in urinary histamine. Guanethidine and imidazole neither potentiated nor mimicked the action of histamine on the isolated ileum.

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.

Variations in oxytocin secretion during the 4-day oestrous cycle of the rat

1993 ◽  
Vol 136 (2) ◽  
pp. 305-311 ◽  
Author(s):  
R. J. Windle ◽  
M. L. Forsling
Keyword(s):  
Clearance Rate ◽  
Significant Variation ◽  
Plasma Clearance ◽  
Plasma Concentrations ◽  
Oestrous Cycle ◽  
Female Rats ◽  
Male Rats ◽  
Hormone Release ◽  
Diurnal Pattern ◽  
The Hours

ABSTRACT Oxytocin concentrations in the plasma, pituitary and hypothalamus of female rats were determined in the morning and evening over the 4-day oestrous cycle. Vasopressin concentrations were also determined to allow calculation of the ratios of the two hormones. The results were compared with those from male rats. Plasma oxytocin concentrations were significantly higher in the evening than in the morning on the day of oestrus. Although the evening concentration achieved was similar on each day of the cycle, morning plasma oxytocin concentrations showed a progressive rise from oestrus to pro-oestrus so that no significant diurnal increases were observed on the other days of the cycle. Vasopressin concentrations in the plasma were also seen to increase over the days of oestrus, dioestrus day 1 and dioestrus day 2. On pro-oestrus the plasma concentrations of vasopressin remained unchanged. The ratio of oxytocin:vasopressin fell during the light hours of the cycle. The hypothalamic content of both hormones showed a rise during the hours of daylight parallel to that seen in the plasma, whereas the pituitary content fell over the same period. The diurnal pattern of hormone release observed in male rats was similar to that in females at oestrus. However, the plasma oxytocin concentrations were significantly higher in the male. The plasma clearance rate of vasopressin did not vary significantly during the oestrous cycle. However, the plasma clearance rate for oxytocin did show significant variation, being highest on dioestrus day 1 and lowest on dioestrus day 2. Journal of Endocrinology (1993) 136, 305–311

scholarly journals NAFENOPIN-INDUCED HEPATIC MICROBODY (PEROXISOME) PROLIFERATION AND CATALASE SYNTHESIS IN RATS AND MICE

1974 ◽  
Vol 61 (2) ◽  
pp. 344-358 ◽  
Author(s):  
Jarnardan K. Reddy ◽  
Daniel L. Azarnoff ◽  
Donald J. Svoboda ◽  
Jada D. Prasad
Keyword(s):  
Catalase Activity ◽  
Fold Increase ◽  
Female Rats ◽  
Male Rats ◽  
Wild Type ◽  
Rapid Reduction ◽  
Male And Female ◽  
Male And Female Rats ◽  
Rats And Mice ◽  
Catalase Protein

Nafenopin (2-methyl-2[p-(1,2,3,4-tetrahydro-1-naphthyl)phenoxy]-propionic acid; Su-13437), a potent hypolipidemic compound, was administered in varying concentrations in ground Purina Chow to male and female rats, wild type (Csa strain) mice and acatalasemic (Csb strain) mice to determine the hepatic microbody proliferative and catalase-inducing effects. In all groups of animals, administration of nafenopin at dietary levels of 0.125% and 0.25% produced a significant and sustained increase in the number of peroxisomes. The hepatic microbody proliferation in both male and female rats and wild type Csa strain mice treated with nafenopin was of the same magnitude and was associated with a two-fold increase in catalase activity and in the concentration of catalase protein. The increase in microbody population in acatalasemic mice, although not accompanied by increase in catalase activity, was associated with a twofold increase in the amount of catalase protein. The absence of sex difference in microbody proliferative response in nafenopin-treated rats and wild type mice is of particular significance, since ethyl-α-p-chlorophenoxyisobutyrate (CPIB)-induced microbody proliferation and increase in catalase activity occurred only in males. Nafenopin can, therefore, be used as an inducer of microbody proliferation and of catalase synthesis in both sexes of rats and mice. The serum glycerol-glycerides were markedly lowered in all the animals given nafenopin, which paralleled the increase in liver catalase. All the above effects of nafenopin were fully reversed when the drug was withdrawn from the diet of male rats. During reversal, several microbody nucleoids were seen free in the hyaloplasm or in the dilated endoplasmic reticulum channels resulting from a rapid reduction in microbody matrix proteins after the withdrawal of nafenopin from the diet. Because of microbody proliferation and catalase induction with increasing number of hypolipidemic compounds, additional studies are necessary to determine the interrelationships of microbody proliferation, catalase induction, and hypolipidemia.

Radioimmunoassay of inhibin in various mammals

1989 ◽  
Vol 122 (3) ◽  
pp. 697-704 ◽  
Author(s):  
T. Hamada ◽  
G. Watanabe ◽  
T. Kokuho ◽  
K. Taya ◽  
S. Sasamoto ◽  
...  
Keyword(s):  
Adult Male ◽  
Follicular Fluid ◽  
Plasma Concentrations ◽  
High Titre ◽  
Female Rats ◽  
Male Rats ◽  
Pituitary Cells ◽  
Peripheral Plasma ◽  
Male And Female Rats ◽  
Tissue Homogenates

ABSTRACT A sensitive radioimmunoassay (RIA) for the determination of inhibin in peripheral plasma and tissue homogenates of different species has been developed using antisera to partially purified bovine follicular fluid (bFF) inhibin and 125I-labelled bFF 32 kDa inhibin. Antisera were produced by immunization of rabbits with partially purified bFF inhibin prepared by immunoaffinity chromatography. Increasing doses of a high titre antiserum could neutralize the suppressing effect of bFF, porcine follicular fluid and rat ovarian homogenate on FSH secretion from rat anterior pituitary cells in culture. Sensitivity of the assay was 3·1 ng International Research Standard of porcine inhibin per tube. Parallel inhibition curves were obtained for inhibin preparations from female and male animals of ten species, i.e. cattle, goats, sheep, cats, dogs, monkeys, pigs, horses, rats and man. Inhibin subunits and related proteins cross-reacted minimally with the antiserum used in the study. Plasma concentrations of inhibin in adult male and female rats were measured by the RIA before and at various times after gonadectomy. Inhibin levels in peripheral plasma before gonadectomy were significantly higher in adult female than in adult male rats. Inhibin levels decreased abruptly after gonadectomy in both sexes and they correlated negatively with plasma concentrations of FSH. This inhibin RIA will facilitate studies of the physiology of inhibin in various species of animals. Journal of Endocrinology (1989) 122, 697–704

Daily exercise and gender influence postexercise cardiac autonomic responses in hypertensive rats

1997 ◽  
Vol 272 (3) ◽  
pp. H1412-H1418 ◽  
Author(s):  
Y. Chen ◽  
M. P. Chandler ◽  
S. E. DiCarlo
Keyword(s):  
Acute Exercise ◽  
Female Rats ◽  
Male Rats ◽  
Autonomic Response ◽  
Hypertensive Rats ◽  
Experimental Conditions ◽  
Autonomic Responses ◽  
Gender Influence ◽  
Single Bout ◽  
And Gender

The influence of daily spontaneous running (DSR) and gender on postexercise cardiac autonomic responses was examined in spontaneously hypertensive rats. Rats were weaned at 4-5 wk of age and were randomly assigned to a sedentary (7 males and 6 females) or DSR (7 males and 8 females) group. After 8 weeks of DSR or sedentary control, rats were chronically instrumented with arterial and venous catheters. After 5 days of recovery, cardiac sympathetic (ST) and parasympathetic tonus (PT) were determined (by the response of heart rate to receptor antagonists) on alternate days under two experimental conditions: no exercise and postexercise. After a single bout of dynamic treadmill exercise (12 m/min, 10% grade for 40 min) ST was reduced (P < 0.05) (male sedentary: no exercise 45 +/- 4 vs. postexercise 28 +/- 3 beats/min; female sedentary: no exercise 69 +/- 10 vs. postexercise 37 +/- 7 beats/ min). PT was also altered after exercise (male sedentary: no exercise -31 +/- 4 vs. postexercise -11 +/- 2 beats/min; female sedentary: no exercise -5 +/- 4 vs. postexercise 7 +/- 4 beats/min). After DSR, ST was reduced (male sedentary 45 +/- 4 vs. DSR 22 +/- 3 beats/min; female sedentary 69 +/- 10 vs. DSR 36 +/- 4 beats/min) (P < 0.05). Finally, male rats had a lower ST and higher PT than female rats. These results demonstrate that 1) ST was reduced after a single bout of dynamic exercise; 2) ST was reduced after DSR; 3) the autonomic response to acute exercise was attenuated after DSR; and 4) there was a gender influence on the cardiac autonomic function.

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