The value of plasma prolactin levels in the prediction of the responsiveness of growth hormone secretion to bromocriptine and TRH in acromegaly

ABSTRACT Effects of chlorpromazine (CPZ) on plasma GH and prolactin levels were observed in conscious rats provided with chronic indwelling right atrial cannulae. The administration of CPZ (200 μg/100 g b.w. iv) suppressed episodic plasma GH burst and resulted in significant elevations of plasma prolactin levels. These were also observed in rats in which two types of hypothalamic deafferentation, i.e. anterior and complete, had been carried out. The data suggest that CPZ acts within the medial basal hypothalamus and inhibits episodic plasma GH secretion. In addition, it is inferred that catecholamines are involved in the generation of episodic plasma GH burst.

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EFFECT OF CHICKEN HYPOTHALAMUS ON PROLACTIN AND GROWTH HORMONE SECRETION IN MALE CHICKENS

Journal of Endocrinology ◽

10.1677/joe.0.0820193 ◽

1979 ◽

Vol 82 (2) ◽

pp. 193-197 ◽

Cited By ~ 18

Author(s):

S. HARVEY ◽

C. G. SCANES ◽

A. CHADWICK ◽

G. BORDER ◽

N. J. BOLTON

Keyword(s):

Growth Hormone ◽

Medulla Oblongata ◽

Hormone Secretion ◽

Growth Hormone Secretion ◽

Pituitary Cells ◽

Plasma Prolactin ◽

Gh Secretion ◽

Brain Tissues

SUMMARY The effects of a chicken hypothalamic extract (HE) on the secretion of prolactin and growth hormone (GH) in vivo have been investigated by radioimmunoassay in the domestic fowl. Different i.v. doses of HE (0·25–25 HE equivalents/kg body weight) had no effect on GH secretion in conscious or anaesthetized cockerels. In both groups of birds the concentration of plasma prolactin was significantly increased within 10 min of administration of the extract. Extracts of other brain tissues (cerebral cortex, cerebellum and medulla oblongata) had no stimulatory effect on prolactin or GH secretion. Release of both prolactin and GH by dispersed pituitary cells and by hemipituitary glands in vitro was enhanced following incubation with HE (5 hypothalami equivalents/ml) or with single whole hypothalami respectively. Other brain tissues (cerebellum, optic lobes and medulla oblongata) had no effect on the concentration of prolactin or GH released by incubated hemipituitary glands.

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Episodic prolactin and growth hormone secretion not related to the actual suckling activity in lactating rats

Journal of Endocrinology ◽

10.1677/joe.0.1110137 ◽

1986 ◽

Vol 111 (1) ◽

pp. 137-142 ◽

Cited By ~ 11

Author(s):

G. Nagy ◽

B. Kacsóh ◽

B. Halász

Keyword(s):

Growth Hormone ◽

Hormone Secretion ◽

Growth Hormone Secretion ◽

Blood Sampling ◽

Physical Contact ◽

Plasma Prolactin ◽

Blood Samples ◽

Apparent Correlation ◽

Freely Behaving ◽

Episodic Fluctuations

ABSTRACT In order to characterize the secretion pattern of prolactin and GH in freely behaving lactating rats, frequent serial blood samples were collected through indwelling atrial cannulae and their prolactin and GH concentrations determined by radioimmunoassay. At the time of blood sampling, physical contact with the pups was recorded. Plasma prolactin and GH levels showed episodic changes which were independent of each other and there was no apparent correlation between hormone levels and contact between mother and pups. The data suggest that there are episodic fluctuations in plasma prolactin and GH concentrations in lactating rats. These changes do not appear to be closely correlated with the proximity of the mother to her pups. J. Endocr. (1986) 111, 137–142

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