SECRETION OF LUTEINIZING HORMONE IN OVARIECTOMIZED ADULT RATS TREATED NEONATALLY WITH MONOSODIUM GLUTAMATE

1981 ◽  
Vol 91 (2) ◽  
pp. 341-346 ◽  
Author(s):  
R. G. DYER ◽  
R. F. WEICK ◽  
S. MANSFIELD ◽  
H. CORBET
Keyword(s):  
Monosodium Glutamate ◽  
Pulse Height ◽  
Treated Group ◽  
Experimental Manipulation ◽  
Ovariectomized Rats ◽  
Adult Rats ◽  
Blood Samples ◽  
Oestradiol Benzoate ◽  
And Control ◽  
Lh Secretion

We have studied the possible effects of monosodium glutamate (MSG) on LH secretion in ovariectomized rats. In experiment 1 MSG-treated and control rats were given oestradiol benzoate at noon and 72 h later half the rats in each group were given a second injection of oestradiol benzoate or progesterone. Blood samples were taken immediately before and 6 h after these i.m. injections. At 78 h there were no significant differences in plasma LH concentration measured in the two groups of rats given progesterone or in the two groups given a second injection of oestradiol benzoate although for both MSG-treated and control rats progesterone produced a significantly (P < 0·01) greater LH surge than did oestradiol benzoate. In experiment 2 100 μl blood samples were collected at 5-min intervals for up to 3 h from MSG-treated and control rats. For rats showing more than one pulsatile discharge of LH, peak and trough values for plasma LH concentrations were not significantly influenced by MSG treatment. However the mean pulse height was significantly (P < 0·001) greater in the MSG-treated group than in control rats. Pulsatile release stopped more quickly in the MSG-treated rats and their mean plasma LH concentration after 120 min of blood sampling was significantly (P < 0·05) lower than that obtained in the control animals. Thus, although some aspects of LH secretion seem to be significantly different in MSG-treated rats, these effects may result from the greater sensitivity of the MSG-treated animals to experimental manipulation.

Adrenal progesterone facilitates the negative feedback of oestrogen on LH release in ovariectomized rats

1993 ◽  
Vol 139 (2) ◽  
pp. 253-258 ◽  
Author(s):  
A. M. Salicioni ◽  
R. W. Carón ◽  
R. P. Deis
Keyword(s):  
Ovariectomized Rats ◽  
Adrenal Steroids ◽  
Serum Progesterone ◽  
Oestrogen Treatment ◽  
Ovx Rats ◽  
Serum Lh ◽  
Oestradiol Benzoate ◽  
Lh Release ◽  
Lh Secretion

ABSTRACT There is evidence that the adrenals play a role in the regulation of the synthesis and release of gonadotrophins in various vertebrates. The aim of this study was to determine the part played by adrenal steroids, with special reference to progesterone, on the concentration of LH in ovariectomized (OVX) and oestrogen-primed rats. OVX rats received a single s.c. injection of vehicle or oestradiol benzoate (OB, 20 μg/rat). This day was designated as day 0. Three or four days later (day 3–day 4), the rats were treated with mifepristone (10 mg/kg) or with two doses of progesterone antiserum and blood samples were obtained at 13.00 and 18.00 h. OB treatment of OVX rats reduced serum LH at 13.00 h and 18.00 h on day 3 but only at 13.00 h on day 4. The administration of mifepristone at 08.00 h to OVX and oestrogen-treated rats induced a significant increase in serum LH at 18.00 h on days 3 and 4, without modifying the values at 13.00 h. When mifepristone was given at 13.00 h a much larger increase in serum LH was obtained at 18.00 h. In OVX and oestrogen-treated rats, adrenalectomy on day 2 (08.00–09.00 h) induced an increase in serum LH at 18.00 h similar to that observed in the OVX and oestrogen-primed rats after mifepristone treatment. In order to determine the specificity of the effect of mifepristone, a group of OVX and oestrogentreated rats was injected with progesterone antiserum at 08.00 and 13.00 h on day 3. Serum LH concentrations at 13.00 and 18.00 h on day 3 were similar to values obtained in OVX rats treated with oestrogen and mifepristone. Serum progesterone was measured at 08.00 and 13.00 h in OVX and OVX and oestrogenprimed rats. At both times, values were similar in OVX rats but oestrogen treatment significantly increased serum progesterone levels. The important role of adrenal progesterone on the regulation of LH secretion in OVX and oestrogen-primed rats is evident from these results. Blocking progesterone action at the receptor level, we showed that OB significantly increased LH values at 18.00 h. On the basis of these studies it is tempting to speculate on the possibility of an inhibitory or stimulatory effect of oestrogen on serum LH concentration in OVX rats, according to the presence or absence of adrenal progesterone action. Journal of Endocrinology (1993) 139, 253–258

Dissociation between the ovarian factors controlling sexual receptivity and preovulatory secretion of LH in cyclic female rats

1987 ◽  
Vol 112 (1) ◽  
pp. 133-138 ◽  
Author(s):  
P. Södersten ◽  
P. Eneroth
Keyword(s):  
Sexual Behaviour ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Sexual Receptivity ◽  
Serum Progesterone ◽  
Lh Surge ◽  
Oestradiol Benzoate ◽  
Lh Release ◽  
Lh Secretion ◽  
Intact Rats

ABSTRACT Ovariectomy and treatment with oestradiol benzoate (10 μg OB) on the day before behavioural oestrus eliminated the preovulatory surge of LH and reduced the level of sexual receptivity on the following day. Sexual behaviour, but not the LH surge, was restored by progesterone (0·5 mg) given 18 h later. Injection of OB on the day after behavioural oestrus induced a small release of LH and normal sexual behaviour on the following day. Ovariectomy on the day after behavioural oestrus reduced the stimulatory effect of OB on sexual behaviour and eliminated its weakly stimulatory effect on LH release. Sexual behaviour, but not the small LH surge, was restored in these animals by progesterone (0·5 mg) given 18 h later. Treatment of rats ovariectomized 2 days before the day of the LH surge with implants containing oestradiol or injections of oestradiol (1 μg) induced LH surges but the amplitudes of these LH surges were much smaller than those of the normal LH surge. Treatment of intact rats with OB increased serum progesterone levels 24 h later, an effect which was eliminated by ovariectomy. Injections of LH (20 μg) into intact rats on the day after behavioural oestrus also increased serum progesterone concentrations but failed to stimulate sexual behaviour. It is suggested that OB treatment of intact rats on the day after behavioural oestrus stimulates sexual behaviour by inducing a surge of LH secretion which activates ovarian secretion of progesterone. Thus, oestrogen and progesterone but not the LH surge are essential for sexual behaviour. Whereas oestradiol and progesterone restore normal sexual behaviour in ovariectomized rats, additional ovarian factors may be required for induction of normal LH surges. J. Endocr. (1987) 112, 133–138

Different wavelengths of light on GnRH mRNA, LH, steroid hormones and egg lay in the ageing hens (Gallus gallus domesticus).

2016 ◽  
Vol 5 (06) ◽  
pp. 4597
Author(s):  
Janardhan Reddy Ippala* ◽  
Ashish Mishra ◽  
Mondal S. ◽  
David G. C. ◽  
Ravi Kiran G. ◽  
...  
Keyword(s):  
Steroid Hormones ◽  
Egg Production ◽  
Treated Group ◽  
Reproductive Period ◽  
Control Group ◽  
Blood Samples ◽  
Egg Formation ◽  
High Concentrations ◽  
Normal Spectrum ◽  
And Control

The aim of this study was to investigate the effects of red spectrum of light (650nm, treated n=12) and normal spectrum of light (450nm control=12) on circulating concentrations of luteinizing hormone (LH), progesterone (P4), estradiol (E2β), GnRH mRNA, pause days and egg production in birds later in the reproductive period from 92-102weeks of age. Twenty-four White Leghorn birds of same age group were divided into two groups of 12 in each as control and treated. Birds in the control group were exposed to normal spectrum of light (450nm of length) and birds in the treated group were exposed to red spectrum of light (650nm, treated n=12). Egg production and inter sequence pauses were recorded daily from both the groups. Plasma LH, E2β and P4 concentrations were estimated in blood samples collected at weekly intervals. At 97th weeks of age, blood samples from treated and control birds were obtained every 3 h for 36 h to study the surges of LH. It was found that plasma GnRH was higher (p < 0. 01) in treated birds with high concentrations of LH, its 3 h LH surges, E2β and P4 in plasma. Higher egg production, less pause days in treated birds may be the result of high GnRH associated with positively correlated responses of high concentrations of LH (with regular interval and duration of LH surges), E2β and P4 concentration required for completion of egg formation and oviposition. In conclusion, red spectrum of light enhanced GnRH mRNA (p < 0. 01), increased (p < 0. 01) steroid hormones and LH surges, for egg formation and oviposition and enabled the birds to lay more eggs even later in the productive period with the available resources under normal husbandry practices. 

Effects of bovine follicular fluid on the secretion of LH and FSH in inhibin-immunized seasonally anoestrous ewes

1991 ◽  
Vol 128 (3) ◽  
pp. 403-410 ◽  
Author(s):  
P. G. Knight ◽  
J. H. M. Wrathall ◽  
R. G. Glencross ◽  
B. J. McLeod
Keyword(s):  
Follicular Fluid ◽  
Synthetic Peptide ◽  
Pulse Frequency ◽  
Α Subunit ◽  
Blood Samples ◽  
Gonadotrophin Secretion ◽  
Gonadotrophin Releasing Hormone ◽  
And Control ◽  
Lh Secretion ◽  
Dose Dependent

ABSTRACT It has been shown previously that treatment of seasonally anoestrous ewes with steroid-free bovine follicular fluid (FF), a crude inhibin-containing preparation, leads to a decrease in plasma FSH level which is accompanied by a marked increase in pulsatile LH secretion. Since FF contains several factors (e.g. activin, follistatin, unidentified components) other than inhibin, which might act to modify gonadotrophin secretion, it was of interest to establish whether these concurrent effects of FF on FSH and LH secretion persisted in ewes which had been actively immunized against a synthetic peptide replica of the α subunit of bovine inhibin. In June 1989 (anoestrous period) groups of inhibin-immune and control ewes (n = 5 per group) received 6-hourly s.c. injections of either bovine serum (2 ml) or one of two doses of FF (0·5 ml or 2 ml) for 3 days. Blood was withdrawn at 6-h intervals for 6 days beginning 24 h before the first injection. On the final day of treatment, additional blood samples were withdrawn at 15-min intervals for 8 h to monitor pulsatile LH secretion. Ewes were then challenged with exogenous gonadotrophin-releasing hormone (GnRH; 2 μg i.v. bolus) to assess pituitary responsiveness. In control ewes, FF promoted a dose-dependent suppression of basal (maximum suppression 65%; P < 0·01) and post-GnRH (maximum suppression 72%; P < 0·01) levels of FSH in plasma. This was accompanied by an increase (P < 0·01) in LH pulse frequency from 1·40±0·24 (s.e.m.) to 3·20±0·37 pulses/8 h. In contrast, FF did not affect secretion of either FSH or LH in inhibin-immunized ewes. However, mean plasma LH levels in immunized ewes were significantly lower (43%; P < 0·02) than in control ewes, irrespective of treatment. These findings indicate that in the anoestrous ewe the ability of FF to suppress plasma FSH is due entirely to its content of inhibin, that FF-induced enhancement of pulsatile LH secretion is mediated by inhibin, rather than some additional component of FF, and that immunoneutralization of endogenous inhibin can reduce LH secretion. Journal of Endocrinology (1991) 128, 403–410

Varying sensitivity to the negative oestrogen feedback during the ovarian cycle of female rats: evidence for the involvement of oestrogen and the medial preoptic area

1984 ◽  
Vol 102 (3) ◽  
pp. 287-294 ◽  
Author(s):  
F. Döcke ◽  
W. Rohde ◽  
P. Gerber ◽  
R. Chaoui ◽  
G. Dörner
Keyword(s):  
Preoptic Area ◽  
Medial Preoptic Area ◽  
Ovarian Cycle ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Adult Rats ◽  
Gonadotrophin Secretion ◽  
Arcuate Region ◽  
Lh Secretion ◽  
Follicle Maturation

ABSTRACT The gonadotrophic response to a single injection of oestradiol benzoate (OB) was studied in acutely ovariectomized adult rats during the different stages of a 4-day ovarian cycle. The results showed a sudden decline of the sensitivity to the gonadotrophin-inhibiting effect of OB between metoestrus and dioestrus. This desensitization to the negative oestrogen feedback was probably caused by an oestrogen action on the medial preoptic area (MPOA). In rats ovariectomized and implanted with OB in the MPOA in metoestrus, an s.c. injection of OB on the presumptive day of pro-oestrus did not lower the circulating LH and FSH levels, whereas a clear suppression of gonadotrophin secretion was seen in females implanted with cholesterol in the MPOA or implanted with OB in the hypothalamic ventromedial–arcuate region. Similar findings were obtained in rats which had been ovariectomized 3–4 weeks before implantation. A final experiment demonstrated that bilateral lesioning of the MPOA also reduced the sensitivity to the negative feedback action of oestrogen in long-term ovariectomized rats. In all experiments performed, diminution of the oestrogen-induced inhibition of LH secretion was more marked than that of suppression of FSH secretion. It is proposed that desensitization to the negative oestrogen feedback, probably resulting from an inhibitory oestrogen action on medial preoptic neurones, is a prerequisite for adequate gonadotrophic support of preovulatory follicle maturation in the presence of a continuously rising oestrogen concentration in the blood. J. Endocr. (1984) 102, 287–294

scholarly journals Gonadotropin-secreting cells in ovariectomized rats treated with different oestrogen receptor ligands: a modulatory role for ERβ in the gonadotrope?

2006 ◽  
Vol 188 (2) ◽  
pp. 167-177 ◽  
Author(s):  
J E Sánchez-Criado ◽  
J Martín de las Mulas ◽  
C Bellido ◽  
V M Navarro ◽  
R Aguilar ◽  
...  
Keyword(s):  
Oestrogen Receptor ◽  
Light And Electron Microscopy ◽  
Ovariectomized Rats ◽  
Secretory Process ◽  
Oestrogen Receptors ◽  
Receptor Ligands ◽  
Structural Reorganization ◽  
Relative Contribution ◽  
Oestradiol Benzoate ◽  
Lh Secretion

In the rat, oestrogen is a key regulator of gonadotrophin synthesis and release through activation of oestrogen receptors (ERs). Gonadotropes express α and β isoforms of ER and both can activate transcription in response to oestrogen. These experiments were aimed at evaluating the relative contribution of ERα and ERβ on gonadotrope morphology, progesterone receptor (PR) expression and LH secretion. Ovariectomized rats were daily injected over 3 days with 25 μg oestradiol benzoate, 0.3 or 1.5 mg of the selective ERα agonist propylpyrazole triol (PPT) with or without 1.5, 3.0 or 4.5 mg of the selective ERβ agonist diarylpropionitrile (DPN), DPN alone, and 0.3 or 3 mg of tamoxifen. Controls were given 0.2 ml oil. Serum concentration and pituitary content of LH, gonadotrope PR expression, pituitary PR content, and gonadotrope morphology were analyzed by RIA, immunohistochemistry, Western blotting and light and electron microscopy, respectively. Results showed that PPT reversed all consequences of ovariectomy, DPN mimicked the effects of PPT except for its LH-releasing action and tamoxifen had ERα-like responses. When combined with PPT, DPN attenuated ERα effects without interfering with its LH-releasing activity. Oestradiol benzoate had similar effects to those of combined PPT and DPN. It is suggested that (i) the structural reorganization of the cytoplasmic organelles provided by oestrogen, and the shrinkage of the ovariectomy-induced hypertrophy of gonadotropes, which precedes the expression of PR, are evoked by ERα and modulated, in a ying–yang fashion, by ERβ; and (ii) the oestrogen-dependent exocytosis of LH, the final step in the secretory process, is dependent on ERα exclusively.

EFFECT OF NEONATAL ADMINISTRATION OF STEROIDS OR GONADECTOMY UPON OESTRADIOL-INDUCED LUTEINIZING HORMONE RELEASE IN RATS OF BOTH SEXES

1980 ◽  
Vol 85 (1) ◽  
pp. 69-74 ◽  
Author(s):  
F. GOGAN ◽  
I. A. BEATTIE ◽  
M. HERY ◽  
E. LAPLANTE ◽  
C. KORDON
Keyword(s):  
Luteinizing Hormone ◽  
Sexual Differentiation ◽  
Female Rats ◽  
Male Rats ◽  
Ovariectomized Rats ◽  
Hormone Release ◽  
Adult Rats ◽  
Luteinizing Hormone Release ◽  
Neonatal Administration ◽  
Lh Secretion

SUMMARY Implantation of oestradiol into adult rats of both sexes induced different patterns of LH secretion depending on the time at which gonadectomy or testosterone injection were performed. Castration 2 h after birth allowed an LH peak to occur daily at 18.00 h, but its amplitude was lower than that of adult gonadectomized female rats treated with oestradiol. Castration 24 h after birth elicited two kinds of response; a circadian discharge of LH lower than that of male rats gonadectomized 2 h after birth or a steady low level of LH. The LH rhythmicity induced by implantation of oestradiol was not seen after castration at 8 weeks of age. Neonatal administration of testosterone to female rats prevented the LH peak induced by oestradiol that was seen in adult ovariectomized rats. Neonatal or adult ovariectomy did not interfere with the rhythmical response of LH after implantation of oestradiol. Thus, it is concluded that sexual differentiation of the hypothalamus is primarily of masculine origin.

scholarly journals Plasma LH and FSH in Ewes That Were Either Fertile or Infertile After Long-Term Grazing of Oestrogenic Pasture

1980 ◽  
Vol 33 (2) ◽  
pp. 213 ◽  
Author(s):  
RJ Rodgers ◽  
IJ Clarke ◽  
JK Findlay ◽  
Ainslie Brown ◽  
IA Cumming ◽  
...  
Keyword(s):  
Breeding Season ◽  
Area Under The Curve ◽  
Ovarian Vein ◽  
Blood Samples ◽  
Serial Blood ◽  
Area Unit ◽  
And Control ◽  
Lh Secretion

The levels of plasma LH and FSH were measured in serial blood samples taken at 15-min intervals for 6 h from ewes that had remained fertile after grazing oestrogenic pasture (clover-fertile ewes), from ewes that were permanently affected by clover disease (clover-infertile ewes) and from normal ewes. Two flocks of ewes from different locations were studied. In flock I, tonic LH secretion (total area under the curve of LH concentration versus time, 1 area unit = 1 ng ml- 1 x 1 h) was significantly (P < 0'05) greater in clover-infertile ewes (10'4 area units) during anoestrus than in ewes that had remained fertile after prolonged grazing of oestrogenic clover (5·4 area units). Tonic LH and FSH secretions during the breeding season and FSH secretion during anoestrus were not significantly different. In flock 2, LH levels during the breeding season were significantly (P < 0'05) elevated in clover-infertile ewes (10' 9 area units) compared to normal ewes (5' 4 area units) that had never grazed oestrogenic clover. LH secretion in clover-infertile ewes (7. 8 area units) was intermediate to that found in infertile and control ewes. Concentrations of FSH, progesterone and ovarian vein oestradiol-17 P (Ez) during the breeding season were similar in the three groups.

Sexual differences in the effect of serotonin on LH secretion in rats

1985 ◽  
Vol 109 (3) ◽  
pp. 320-325 ◽  
Author(s):  
Jaime A. Moguilevsky ◽  
María R. Faigón ◽  
Modesto C. Rubio ◽  
Pablo Scacchi ◽  
Berta Szwarcfarb
Keyword(s):  
Sexual Differences ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Adult Rats ◽  
Serotoninergic Neurons ◽  
Male And Female Rats ◽  
Lh Release ◽  
Prepubertal Rats ◽  
Lh Secretion ◽  
The Brain

Abstract. The effect of 5-hydroxytryptophan (5-HTP), a serotonin (5-HT) precursor, on luteinizing hormone (LH) secretion was studied in prepubertal male and female rats of different ages. In females 5-HTP stimulated LH release on days 16, 18 and 20 but not in older rats (26, 30, 35 days of age). No effects of 5-HTP on LH levels were observed in males. The positive feed-back mechanism of oestrogen-progesterone (E-P), that normally matures in the female between 20 and 26 days, was inhibited by 5-HTP in all the ages studied during prepuberty (26, 30 and 35 days old). On the other hand, in adult ovariectomized rats, 5-HTP administration not only decreased the high LH levels induced by ovariectomy, but the LH release response to E-P as well. These results indicate that there are sexual differences in the effect of 5-HT on LH in prepubertal rats younger than 26 days old. Administration of p-chloroamphetamine (PCA) a serotonin neurotoxin selective for serotoninergic neurons that depletes 5-HT levels in the brain, induced a significant increase in the LH release response to LRH in females, but had no effect in males. These results, besides suggesting a probable pituitary participation in the 5-HT action on LH secretion in the female, appear to indicate the existence of sexual differences in the effect of 5-HT in adult rats.

scholarly journals Effect of Adiponectin Hormone on Serum Lipoproteins Levels in Female Rats

2013 ◽  
Vol 12 (2) ◽  
pp. 50
Author(s):  
H, A. A. Al-Baka`a
Keyword(s):  
Normal Saline ◽  
Treated Group ◽  
Female Rats ◽  
Control Group ◽  
Serum Lipoproteins ◽  
Control Groups ◽  
Dose Administration ◽  
Blood Samples ◽  
And Control

This investigation aimed to study the effect of adiponectin hormone on serum lipoproteins levels in female rats. For this purpose, thirteen female rats were divided into treated and control groups. Each animal in the treated group received a daily intraperitoneal 25microgram does of adiponectin dissolved in 0.2ml normal saline for fifteen respective days. In the same time, each animal in the control group received a daily intraperitoneal 0.2ml normal saline for fifteen respective days. The animal has fasted for 12 hours after last dose administration. Blood samples were collected, and the sera obtained. Analysis showed a significant increase in the serum HDL level and a significant decrease in LDL concentration. AP < 0.05was considered significant.

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