Regional Patterning of Hormones in the Female Rat Anterior Pituitary: Disproportionate Changes Over the Estrous Cycle

1988 ◽  
Vol 14 (4) ◽  
pp. 263-282 ◽  
Author(s):  
Jerome M. Goldman ◽  
Ralph L. Cooper ◽  
Georgia L. Rehnberg ◽  
Kimberly C. Booth ◽  
W. Keith McElroy ◽  
...  
Keyword(s):  
Estrous Cycle ◽  
Anterior Pituitary ◽  
Female Rat

scholarly journals The influence of 17β-estradiol on annexin 1 expression in the anterior pituitary of the female rat and in a folliculo-stellate cell line

2007 ◽  
Vol 192 (2) ◽  
pp. 429-442 ◽  
Author(s):  
Evelyn Davies ◽  
Selma Omer ◽  
John F Morris ◽  
Helen C Christian
Keyword(s):  
Cell Line ◽  
Estrous Cycle ◽  
Anterior Pituitary ◽  
Stellate Cell ◽  
Ovariectomized Rats ◽  
Female Rat ◽  
Annexin 1 ◽  
17Β Estradiol ◽  
Estrous Cycle Stage

Annexin 1 (ANXA1) is a Ca2+- and phospholipid-binding protein that plays an important role as a mediator of glucocorticoid action in the host-defence and neuroendocrine systems. Sex differences in hypothalamo–pituitary–adrenal (HPA) axis activity are well documented and a number of studies have demonstrated that gonadal steroids act as regulators of HPA activity. The aim of this study was to investigate the effect of ovariectomyand 17β-estradiol replacement, and estrous cycle stage, on anterior pituitary ANXA1 content. The amount of anterior pituitary ANXA1 determined by western blotting varied with estrous cycle stage with a peak at estrus declining to a trough at proestrus. Ovariectomy resulted in a significant (P<0.05) decrease in anterior pituitary ANXA1 content. Administration of 17β-estradiol (1 μg/100 g) significantly (P<0.01) increased anterior pituitary ANXA1 expression in the ovariectomized animals. In contrast, there was no change in pituitary ANXA1 content in response to 17β-estradiol in adrenalectomized and adrenalectomized/ovariectomized rats. Treatment of TtT/GF cells, a folliculo-stellate cell line, with 17β-estradiol (1.8–180 nM) increased ANXA1 mRNA expression and increased the amount of ANXA1 protein externalized in response to a dexamethasone stimulus. These results indicate that 17β-estradiol stimulates ANXA1 expression in the anterior pituitary and in vivo an adrenal factor contributes to the mechanism of action.

scholarly journals In vitro effect of leptin on LH release by anterior pituitary glands from female rats at the time of spontaneous and steroid-induced LH surge

2001 ◽  
pp. 659-665 ◽  
Author(s):  
SN De Biasi ◽  
LI Apfelbaum ◽  
ME Apfelbaum
Keyword(s):  
Estrous Cycle ◽  
Anterior Pituitary ◽  
Female Rats ◽  
Female Rat ◽  
Lh Surge ◽  
Pituitary Glands ◽  
Lh Release ◽  
Vitro Effect ◽  
Stimulation Of

OBJECTIVE: The purpose of this work was to study the direct effect of leptin on LH release by anterior pituitary glands from female rats at the time of spontaneous and steroid-induced LH surge. METHODS: LH responsiveness to leptin by pituitaries from rats killed in the afternoon (1500 h) at different stages of the 4-day estrous cycle (diestrus-1: D1; diestrus-2: D2; proestrus; estrus), ovariectomized (OVX; 15 days post-castration) and ovariectomized steroid-primed (OVX-E(2)/Pg; pretreated with 5 microg estradiol and 1 mg progesterone), was evaluated in vitro. Hemi-adenohypophyses were incubated in the presence of synthetic murine leptin for 3 h. RESULTS: Addition of increasing concentrations of leptin (0.1-100 nmol/l) to the incubation medium of proestrus pituitaries produced a dose-related stimulation of LH release; the maximal increase to 315% of control was obtained with 10 nmol/l leptin. Leptin (10 nmol/l) enhanced LH release at all days of the estrous cycle, the greatest response occurring in proestrus (318%) and the lowest at D1 (123%). In order to evaluate the role of nitric oxide (NO) in the action of leptin on LH release, glands from proestrus rats were incubated in the presence of 10 nmol/l leptin with or without 0.3 mmol/l N(G)-monomethyl-l-arginine (NMMA), a competitive inhibitor of NO synthase (NOS). NMMA completely suppressed the stimulation of LH release induced by leptin. Leptin also stimulated LH release by pituitaries from OVX rats, and treatment with steroid hormones led to a marked increase in the response (OVX: 162% compared with OVX-E(2)/Pg: 263%; P<0.05). For comparative analysis, a similar experimental procedure was carried out using GnRH (10 nmol/l). Leptin acts at the pituitary level in a similar manner as GnRH, although with significantly lower potency. CONCLUSIONS: These results confirm and extend previous reports regarding a direct action of leptin at the pituitary level, stimulating LH release by anterior pituitaries from female rats at the time of spontaneous and steroid-induced LH surge. In the female rat pituitary this leptin action is controlled by gonadal steroids and mediated by NO.

THE ONSET OF ALLOMETRIC MAMMARY GROWTH IN THE FEMALE HOODED NORWAY RAT

1953 ◽  
Vol 10 (1) ◽  
pp. 35-45 ◽  
Author(s):  
MARIAN SILVER
Keyword(s):  
Growth Rate ◽  
Anterior Pituitary ◽  
Intact Animal ◽  
Mammary Glands ◽  
Mammary Development ◽  
Female Rat ◽  
Suckling Period ◽  
Intact Female ◽  
Norway Rat ◽  
Endogenous Oestrogen

SUMMARY In order to study the factors involved in the initiation of allometric mammary growth, which occurs at about 3 weeks of age in the intact female rat, an attempt to induce this phase prematurely in the suckling gonadectomized animal by means of oestrogen was made. It was found, however, that the mammary glands were practically insensitive to physiological doses of this hormone during the suckling period unless anterior pituitary (a.p.) extract was also given. The relative mammary growth rate in animals treated with a.p. plus oestrogen from the 10th to 27th day of life was similar to that found in control rats receiving oestrogen alone from the 20th to 36th day, but in the former groups allometry was initiated before the 20th day of life. It is suggested that both the level of endogenous oestrogen secretion and the functional activity of the anterior pituitary may be important in determining the time of onset of allometric mammary development in the intact animal.

Influence of the estrous cycle on hypoxic failure in the female rat heart

2009 ◽  
Vol 6 (4) ◽  
pp. 596-603 ◽  
Author(s):  
Tom L. Broderick ◽  
Peter Wong
Keyword(s):  
Estrous Cycle ◽  
Rat Heart ◽  
Female Rat
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