SPECIFIC BINDING OF LH-RH TO THE ANTERIOR PITUITARY GLAND DURING THE OESTROUS CYCLE IN THE RAT

1976 ◽  
Vol 82 (1) ◽  
pp. 62-70 ◽  
Author(s):  
K. R. Park ◽  
B. B. Saxena ◽  
H. M. Gandy
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Specific Binding ◽  
Anterior Pituitary Gland ◽  
Oestrous Cycle ◽  
Lh Rh

Relationship between endogenous opioids and the oestrous cycle in the rat

1984 ◽  
Vol 100 (3) ◽  
pp. 271-275 ◽  
Author(s):  
G. K. Hulse ◽  
G. J. Coleman ◽  
D. L. Copolov ◽  
J. A. Clements
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Ovarian Hormones ◽  
Endogenous Opioids ◽  
Anterior Pituitary Gland ◽  
Oestrous Cycle ◽  
Neurointermediate Lobe ◽  
Response To Stress ◽  
Induced Changes

ABSTRACT The aim of this study was twofold: (1) to document changes in levels of immunoreactive β-endorphin (Ir-β-EP) in the hypothalamus, anterior pituitary gland, neurointermediate lobe and plasma during the oestrous cycle of the rat and (2) to investigate stress-induced changes in plasma Ir-β-EP at different stages of the oestrous cycle. Evidence was found that Ir-β-EP levels in the hypothalamus, anterior pituitary gland and plasma are not constant during the oestrous cycle and that the Ir-β-EP response to stress is a function of the phase of the oestrous cycle at which stress is applied. It is suggested that fluctuations in ovarian hormones may influence oestrous Ir-β-EP levels both under normal conditions and after exposure to stress. J. Endocr. (1984) 100, 271–275

Ornithine decarboxylase activity and polyamines in the anterior pituitary gland during the rat oestrous cycle

1985 ◽  
Vol 107 (1) ◽  
pp. 83-87 ◽  
Author(s):  
L. Persson ◽  
M. Nilsson ◽  
E. Rosengren
Keyword(s):  
Pituitary Gland ◽  
Ornithine Decarboxylase ◽  
Anterior Pituitary ◽  
Anterior Pituitary Gland ◽  
Oestrous Cycle ◽  
Ovariectomized Rats ◽  
Oestrogen Treatment ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Lh Releasing Hormone

ABSTRACT The biosynthesis of polyamines, an ubiquitous group of amines shown to be essential for normal cellular growth and differentiation, was studied in the rat anterior pituitary gland during the different stages of the oestrous cycle. The activity of ornithine decarboxylase (ODC), which catalyses the rate-limiting step in the biosynthesis of polyamines, was low during oestrus, metoestrus and dioestrus. However, a marked transitory rise in ODC activity was found in the pituitary gland on the evening of pro-oestrus. The rise in ODC activity was accompanied by an increase in the pituitary content of the polyamines putrescine and spermidine. Ovariectomy did not significantly change the basal ODC activity in the pituitary gland. Oestrogen treatment of ovariectomized rats resulted in a marked stimulation of pituitary polyamine biosynthesis. The largest effects were observed when oestrogen was given as two injections 72 h apart, which gave rise to levels of ODC activity comparable to those observed on the evening of pro-oestrus. The increase in polyamine synthesis in the anterior pituitary gland during pro-oestrus appeared not to be related to the preovulatory secretion of LH or prolactin, since neither LH-releasing hormone nor thyrotrophin-releasing hormone (which induces a secretion of prolactin) affected pituitary ODC activity. The observed biosynthesis of polyamines may be associated with the cellular proliferation which occurs in the anterior pituitary gland at oestrus. J. Endocr. (1985) 107, 83–87

OESTRADIOL RECEPTORS IN THE RAT ANTERIOR PITUITARY GLAND DURING THE OESTROUS CYCLE: QUANTITATION OF RECEPTOR ACTIVITY IN RELATION TO GONADOTROPHIN RELEASING HORMONE-MEDIATED LUTEINIZING HORMONE RELEASE

1978 ◽  
Vol 76 (2) ◽  
pp. 211-218 ◽  
Author(s):  
K. K. SEN ◽  
K. M. J. MENON
Keyword(s):  
Pituitary Gland ◽  
Binding Sites ◽  
Anterior Pituitary ◽  
Anterior Pituitary Gland ◽  
Oestrous Cycle ◽  
Hormone Release ◽  
Releasing Hormone ◽  
Lh Release ◽  
Gonadotrophin Releasing Hormone ◽  
Stimulation Of

Specific oestradiol binding to a receptor in nuclear and cytosol fractions of the rat anterior pituitary gland and pituitary responsiveness to gonadotrophin releasing hormone (GnRH) during the oestrous cycle have been studied. To accomplish this, both unoccupied and occupied oestradiol-binding sites in the cytosol and oestradiol-binding sites in the nucleus and total cell were measured during the oestrous cycle. The concentration of unoccupied and occupied sites and total oestradiol binding in the cytosol fluctuated during the cycle. At pro-oestrus, the concentration of cytosol receptor was diminished by about 40% and replenishment occurred during oestrus. On the other hand, a profound increase in concentrations of cellular and nuclear receptors occurred at pro-oestrus. Administration of GnRH significantly stimulated LH release at all stages of the cycle. The maximum stimulation of LH release by GnRH was observed at 13.00 h of pro-oestrus. From these studies, it is concluded that pituitary responsiveness to exogenous GnRH during pro-oestrus parallels the changes in the content of oestrogen receptors in the cytosol and nucleus.

POSSIBLE PRIMING EFFECT OF LUTEINIZING HORMONE RELEASING HORMONE ON THE ANTERIOR PITUITARY GLAND IN THE JAPANESE QUAIL AND THE STIMULATION OF SECRETION OF FOLLICLE-STIMULATING HORMONE

1979 ◽  
Vol 82 (1) ◽  
pp. 71-75 ◽  
Author(s):  
D. T. DAVIES ◽  
J. COLLINS
Keyword(s):  
Pituitary Gland ◽  
Japanese Quail ◽  
Anterior Pituitary ◽  
Follicle Stimulating Hormone ◽  
Anterior Pituitary Gland ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Lh Rh ◽  
Lh Releasing Hormone ◽  
Stimulation Of

SUMMARY After the i.m. injection of 10 μg synthetic LH releasing hormone (LH-RH) into Japanese quail the levels of LH and FSH in plasma rose significantly within 2 min. The increased level of LH declined rapidly but that of FSH was maintained for the duration of the experiment. To determine whether the anterior pituitary gland is primed by LH-RH a double injection schedule was adopted. It would appear that, while endogenous LH-RH may prime the avian pituitary gland slightly, synthetic LH-RH is ineffective.

Effect of stress on tissue and plasma levels of immunoreactive β-endorphin in ovariectomized rats primed with oestrogen and progesterone

1984 ◽  
Vol 100 (3) ◽  
pp. 277-280 ◽  
Author(s):  
G. K. Hulse ◽  
G. J. Coleman
Keyword(s):  
Pituitary Gland ◽  
Plasma Levels ◽  
Anterior Pituitary ◽  
Sesame Oil ◽  
Anterior Pituitary Gland ◽  
Oestrous Cycle ◽  
Ovariectomized Rats ◽  
Neurointermediate Lobe ◽  
Pituitary Tissue

ABSTRACT The aim of this study was to investigate the effect of oestrogen and progesterone on levels of immunoreactive β-endorphin (Ir-β-EP) in the hypothalamus, anterior pituitary gland, neurointermediate lobe and plasma under normal conditions and conditions of stress. The injection of oestrogen + progesterone into ovariectomized rats increased Ir-β-EP levels in extracts of anterior pituitary tissue and in plasma, under both normal and stressed conditions. Exposure to a stress reduced the content of anterior pituitary Ir-β-EP in ovariectomized rats treated with oestrogen + progesterone and also with sesame oil. Such treatment only resulted in increments in plasma Ir-β-EP in oil-treated but not in oestrogen + progesterone-treated overiectomized rats. It was concluded (1) that oestrogen and progesterone are involved in the regulation of resting levels of anterior pituitary Ir-β-EP during the rat oestrous cycle, (2) that stress reduces levels of anterior pituitary Ir-β-EP and (3) that increased levels of plasma oestrogen + progesterone inhibit plasma Ir-β-EP increments which normally accompany exposure to stress. J. Endocr. (1984) 100, 277–280

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