EFFECTS OF STILBOESTROL ON GROWTH HORMONE SECRETION AND PITUITARY CELL PROLIFERATION IN THE MALE RAT

1971 ◽  
Vol 51 (3) ◽  
pp. 473-481 ◽  
Author(s):  
H. M. LLOYD ◽  
J. D. MEARES ◽  
JOAN JACOBI ◽  
FRANCES J. THOMAS
Keyword(s):  
Growth Hormone ◽  
Cell Proliferation ◽  
Mitotic Activity ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Mean Value ◽  
Pituitary Cell ◽  
Male Rats ◽  
Male Rat ◽  
Serum Growth Hormone

SUMMARY A single 12 mg dose of stilboestrol dipropionate given to 100-day-old male rats resulted in increased pituitary mitotic activity, pituitary weight and serum growth hormone; the latter rose from a mean value of 20 ng/ml to a maximum of 342 ng/ml 9 days later. Serum growth hormone and pituitary mitotic activity then gradually diminished but were still slightly increased on day 28. Serum growth hormone and pituitary weight were significantly correlated during the periods of rapidly rising and of sustained high levels of serum growth hormone. Indices of mitotic activity were correlated with serum growth hormone during the periods of rapidly rising and of falling levels of serum growth hormone.

EARLY EFFECTS OF STILBOESTROL ON GROWTH HORMONE AND PROLACTIN SECRETION AND ON PITUITARY MITOTIC ACTIVITY IN THE MALE RAT

1973 ◽  
Vol 58 (2) ◽  
pp. 227-231 ◽  
Author(s):  
H. M. LLOYD ◽  
J. D. MEARES ◽  
JOAN JACOBI
Keyword(s):  
Growth Hormone ◽  
Mitotic Activity ◽  
Single Injection ◽  
Prolactin Secretion ◽  
Male Rats ◽  
Male Rat ◽  
Serum Prolactin ◽  
Serum Growth Hormone ◽  
Total Period ◽  
Early Effects

SUMMARY The effects of a single injection of 1 mg diethylstilboestrol dipropionate on pituitary mitotic activity and on secretion of growth hormone and prolactin were investigated in male rats on each of the first 15 days following the single dose and then at intervals for a total period of 63 days. Mitotic activity increased to a maximum on day 4 and then gradually diminished. Serum growth hormone was moderately increased during the 2nd week and serum prolactin showed a gradual rise with a return to normal on day 63. In the pituitary gland, growth hormone concentration diminished until day 28, whereas prolactin rose quickly at first, maintained a raised level and increased further on day 43. During the first 12 days, pituitary weight was significantly correlated with serum growth hormone and prolactin concentration. During days 13–28, serum prolactin, but not growth hormone, was significantly correlated with the pituitary mitotic index.

DNA SYNTHESIS AND DEPLETION OF PROLACTIN IN THE PITUITARY GLAND OF THE MALE RAT

1978 ◽  
Vol 77 (1) ◽  
pp. 129-136 ◽  
Author(s):  
H. M. LLOYD ◽  
J. M. JACOBI ◽  
J. D. MEARES
Keyword(s):  
Growth Hormone ◽  
Dna Synthesis ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Prolactin Secretion ◽  
Male Rats ◽  
Male Rat ◽  
Serum Prolactin ◽  
Inhibitory Effects ◽  
Pituitary Prolactin

Haloperidol, bromocriptine and diethylstilboestrol dipropionate were given in various régimes to male rats to determine their effects on pituitary DNA synthesis, prolactin secretion and growth hormone secretion. Haloperidol increased serum prolactin but did not stimulate pituitary DNA synthesis or reduce pituitary prolactin concentrations. Haloperidol potentiated the effects of oestrogen on serum prolactin and on pituitary DNA synthesis; pituitary prolactin concentrations were greatly reduced, and growth hormone secretion was slightly inhibited. The inhibitory effects of bromocriptine in oestrogen-stimulated rats were demonstrated by smaller pituitary weights and decreased DNA synthesis; serum prolactin levels were lowered and pituitary prolactin concentrations were increased. Haloperidol, given to rats treated with oestrogen and bromocriptine, reversed the inhibitory effects of bromocriptine on DNA synthesis and serum prolactin; pituitary prolactin concentrations fell to well below normal. The results suggest that the haloperidol potentiation of oestrogeninduced pituitary DNA synthesis may depend upon stimulation of prolactin secretion together with reduction of intracellular prolactin levels.

In vivo evidence of a positive role for somatostatin to optimize pulsatile growth hormone secretion

1995 ◽  
Vol 269 (4) ◽  
pp. E683-E690 ◽  
Author(s):  
J. P. Turner ◽  
G. S. Tannenbaum
Keyword(s):  
Growth Hormone ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Convincing Evidence ◽  
Male Rats ◽  
Male Rat ◽  
Normal Male ◽  
Positive Role ◽  
Analogue Octreotide

Despite convincing evidence that somatostatin (SRIF) and growth hormone (GH)-releasing factor (GRF) individually play crucial roles in GH regulation, the nature of the interplay between these two hypothalamic hormones is far from clear. In the present study, we used the long-acting SRIF analogue, octreotide, as a probe in both the normal and mutant dwarf (dw) rat 1) to further elucidate the temporal nature of the SRIF-GRF interaction in vivo and 2) to define possible mechanisms of action of SRIF in generating pulsatile GH secretion. Normal free-moving adult male rats pretreated with octreotide (25 and 50 micrograms iv) and subsequently challenged with GRF (1 micrograms iv) exhibited a markedly blunted GH response to exogenous GRF 1 h after treatment. In contrast, preexposure to octreotide for 3 h produced a two- to threefold augmentation in GH responsiveness to GRF. Compared with normal saline-pretreated controls, 3-h pretreatment with octreotide produced a 14- to 16-fold augmentation in the postinhibitory rebound release of GH after the coadministration of native SRIF-14 and GRF (P < 0.001). In dw rats, which show a selective reduction in GH synthesis and storage, 3-h preexposure to octreotide failed to significantly alter GRF-induced GH release. These results demonstrate that, in the normal male rat, a 3-h period of exposure to the SRIF analogue octreotide is sufficient to enhance GH responsiveness to GRF. Our findings suggest that this effect is due to a SRIF-mediated buildup of pituitary GH stores in a readily releasable poo.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Hydroxydopamine Lesions of the Locus Coeruleus Induce a Paradoxical Increase in Growth Hormone Secretion in Male Rats

1992 ◽  
Vol 4 (1) ◽  
pp. 9-14 ◽  
Author(s):  
M. T. Bluet-Pajot ◽  
F. Mounier ◽  
D. Durand ◽  
C. Kordon ◽  
C. Llorens-Cortes ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Locus Coeruleus ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Male Rats ◽  
6 Hydroxydopamine

Somatostatin Inhibits prolactin secretion in the estradiol primed male rat

1981 ◽  
Vol 59 (10) ◽  
pp. 1082-1088 ◽  
Author(s):  
G. R. Cooper ◽  
S. H. Shin
Keyword(s):  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Blocking Agent ◽  
Prolactin Secretion ◽  
Male Rats ◽  
Male Rat ◽  
Dependent Manner ◽  
Intact Male ◽  
Plasma Prl

Somatostatin inhibits not only growth hormone secretion, but also the secretion of several other hormones. The role of somatostatin in prolactin (PRL) secretion has not been clearly demonstrated. The present study was undertaken to examine the effects of somatostatin on rat PRL secretion in several different circumstances where the circulating PRL level is elevated: (1) the estradiol primed intact male rat, (2) normal and (3) estradiol primed rats pretreated with pimozide, (4) normal and (5) estradiol primed hypophysectomized male rats with adenohypophyses grafted under the kidney capsule (HAG rat). Blood samples (70 μL) were taken every 2 min via an indwelling atrial cannula from conscious, unrestrained animals. In the estradiol primed intact rats, a bolus injection of somatostatin (10, 100, and 1000 μg/kg) lowered PRL levels in a dose-dependent manner. When the PRL concentration was elevated by the administration of pimozide (3 mg/kg), a dopaminergic receptor blocking agent, somatostatin was ineffective in decreasing plasma PRL concentration but the PRL concentration was lowered by somatostatin when the rat had been primed with estradiol. Somatostatin had no effect on the normal HAG rats, but lowered the plasma PRL concentration in the estradiol primed HAG rats. Since somatostatin inhibits PRL secretion only in the estradiol primed rats, it is suggested that estradiol priming creates a new environment, presumably via new or altered receptors, which can be inhibited by somatostatin.

Inhibitory effect of leptin on growth hormone secretion of GH3 cells: Involvement of cell proliferation, apoptosis and intracellular free Ca2+

Cytokine ◽  
2009 ◽  
Vol 46 (2) ◽  
pp. 245-250 ◽  
Author(s):  
Yali Liu ◽  
Yanqing Zhong ◽  
Jianming Pei ◽  
Yunlong Zhu ◽  
Yuzhen Hu ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Cell Proliferation ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Inhibitory Effect ◽  
Gh3 Cells
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