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Results for “Prolactin Release-Inhibiting Factors”

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PubMed1977

Hormonal control of zinc uptake and binding in the rat dorsolateral prostate.

The zinc uptake in the dorsolateral prostate of rats was studied after different hormonal manipulations. Orchiectomy reduced the uptake of 65Zn. Administration of estradiol benzoate to orchiectomized rats doubled the 65Zn uptake, a phenomenon which was not observed in orchiectomized-adrenalectomized rats. Adrenalectomy in orchiectomized rats had no effect on the concentration of radioactivity beyond the castration-induced decrease. A prolactin release inhibitor, 6-methyl-8-erogelenylacetamide, reduced the radioactivity concentration without changing the weight of the gland. Cyproterone acetate reduced the weight but not the radioactivity concentration. The concentration of 65Zn in the ventral prostate was not changed by orchiectomy, adrenalectomy, or the administration of estradiol benzoate, prolactin release inhibiors, or cyproterone acetate. The results suggest an important role for prolactin in the zinc uptake in the dorsolateral prostate but not in the ventral prostate.

Acetamides↗
PubMed1977

[Prolactin].

Explore the source record for details and available documents.

Animals↗
PubMed1977

Localization of hypophysiotropic neurohormones by assay of sections from various brain areas.

The results of studies of the localization of the hypothalamic hypophysiotropic factors based on their direct determination in sections or nuclear punches are described. Luteinizing hormone-releasing hormone was found in high concentrations in the median eminence-arcuate nucleus complex, in lower concentrations in the mediobasal zone of the preoptic area. In addition to these hypothalamic sites, it is present in all four periventricular organs, especially in the organum vasculosum laminae terminalis. Thyrotropin releasing hormone has a widespread distribution. High concentrations are in the median eminence, arcuate nucleus, dorsomedial nucleus, and anterior part of the ventromedial nucleus. Lower concentrations are in several other structures of the hypothalamus, preoptic area and septum, and low but measurable quantities are found in most of the structures of the brain. Somatostatin is also present in most structures of the central nervous system, with highest concentrations in the median eminence, arcuate nucleus, ventromedial nucleus and periventricular nucleus. There are indications that the ventromedial nucleus or its immediate vicinity contains growth hormone releasing factor. Prolactin releasing activity was present in the median eminence and mediobasal parts of the anterior hypothalamus, whereas prolactin inhibitory activity was in the dorsolateral parts of the anterior hypothalamus and/or preoptic area.

Animals↗
PubMedDate not supplied

Some new approaches to potential test systems for drugs against prostatic cancer.

We have previously reported on test systems, based on 5alpha-reductase (5alpha-RA) and arginase activities and steroid deposition in animal prostates, potentially useful in screening drugs possibly effective in cancer of the prostate. Recently, we have concentrated on the development of other in vivo and in vitro systems which may prove of further value in testing such drugs. These systems include the following: (a) The effects of drugs on 5alpha-RA activity in human and animal non-malignant and human cancerous prostatic tissues in organ culture. The parameters necessary for the maintenance of optimal 5alpha-RA in such explants have been determined, and it has been shown that certain agents (estramustine phosphate, progesterone, estradiol-17beta) can inhibit 5alpha-RA under in vitro conditions, pointing to the potential use of such an approach in screening various cytostatic agents. In addition, 65Zn deposition, the histology, and the androgen metabolism in such tissues in organ culture are being determined as additional parameters. (b) The deposition of 65Zn in the rat dorsolateral gland, particularly as affected by prolactin and testosterone, and the effects of chemotherapeutic agents on such deposition. Methotrexate and CCNU have been shown to be potent inhibitors of 65Zn deposition in the dorsolateral gland. The parameters related to zinc metabolism in the prostate are being further investigated. (c) The demonstration of receptors for estrogens (estradiol-17beta, diethylstilbestrol) in the prostate of the baboon. The various parameters related to the specificity of such receptors have been established. The development and standardization of these approaches, some facets of which are reported in the present publication, may prove them to be more sensitive, specific, and optimal than other systems and should afford an opportunity to test various combinations of drugs potentially useful in cancer of the prostate with relative speed, efficacy, and ease of manipulation.

Adrenalectomy↗
PubMed1977

Dissociation of growth hormone and prolactin response to levodopa during pyridoxine administration.

500 mg of levodopa was administered orally to 8 normal subjects and induced an increase of growth hormone (GH) and a decrease of prolactin (PRL) secretion. The levodopa-induced GH release was inhibited by an intravenous infusion of pyridoxine; on the contrary, the PRL response to levodopa was enhanced by pyridoxine infusion. This dissociation of GH and PRL responses to levodopa during pyridoxine infusion appears to be mediated by peripheral acceleration of the conversion of levodopa to dopamine. Since dopamine does not penetrate the blood-brain barrier, the enhanced PRL decrease observed during pyridoxine infusion might be explained only on the basis of a mechanism of action exerted by dopamine on extra blood-brain barrier sites.

Adult↗
PubMed1978

Dopaminergic control of prolactin secretion.

A brief summary is given about present-day knowledge and views on the control of prolactin secretion in mammals. This is followed by the presentation of the evidence that dopamine is the inhibitory hypothalamic transducer controlling hormone release by prolactin cells. Most of the evidence is pharmacological in nature. It is only very recently that dopamine has been found in a meaningful concentration in the blood flowing from the median eminence to the pituitary. Although the dopamine concept of an inhibitory control of prolactin secretion seems quite satisfactory, the possibility of another unrelated inhibitory control system is not excluded.

Animals↗
PubMed1978

Hypothalamic regulatory hormones: physiological and clinical implications.

The hypothalamic regulatory hormones used for clinical studies are TRH, Gn-RH and somatostatin. In addition, as dopamine appears to be a physiological PIF, the dopamine agonists such as bromocriptine, could be considered as functional analogues of PIF. Gn-RH can be used to study the hypothalamic-pituitary gonadal relationship and to test the secretory reserve capacity of the gonadotrophs in disease states. Unfortunately Gn-RH testing discrimulates between pituitary and hypothalamic diseases only poorly. However gonadotrophin deficient men or women may be successfully treated with long-term Gn-RH with induction of puberty, potency, spermatogenesis and ovulation. Somatostatin has multiple actions in inhibiting endocrine and exocrine secretion but its actions are still being explored in diabetes. Bromocriptine, a long acting dopamine agonist (a functional analogue of PIF), suppresses prolactin and is highly effective in treating many hypogonadal states since hyperprolactinaemia is common. It also lowers growth hormone in acromegaly. TRH has provided a major, accurate, sensitive and safe test of thyroid function.

Dopamine↗
PubMed1976

Studies of maternal plasma prolactin and amniotic fluid prolactin. Effects of chlorpromazine and prostaglandin F2alpha.

We have studied the effect of chlorpromazine and PGF2alpha on the blood and amniotic fluid levels of prolactin over a 1-hour period of time in women who were in the 14th-20th week of gestation. Following intramuscular injection of chlorpromazine, maternal plasma prolactin rose 1.0- to 2.5-fold. No significant change was noted in maternal plasma after PGF2alpha administration. Amniotic fluid prolactin declined by 6 to 56%. These changes may be dilutional.

Amniotic Fluid↗