UPTAKE AND BINDING OF ANDROGENS BY THE ANTERIOR PITUITARY GLAND, HYPOTHALAMUS, PREOPTIC AREA AND BRAIN CORTEX OF RATS

1974 ◽  
Vol 76 (3) ◽  
pp. 417-430 ◽  
Author(s):  
Oddvar Næss ◽  
Arne Attramadal
Keyword(s):  
Pituitary Gland ◽  
Muscle Tissue ◽  
Anterior Pituitary ◽  
Brain Cortex ◽  
Preoptic Area ◽  
Anterior Pituitary Gland ◽  
Radioactive Material ◽  
Ventral Prostate ◽  
Target Cells ◽  
The Brain

ABSTRACT [1,2-3H] testosterone was given intramuscularly to castrated adult male and female rats. The concentration of radioactivity in the anterior pituitary gland, hypothalamus, preoptic area, brain cortex, ventral prostate and muscle tissue was measured at different time intervals. In the ventral prostate a preferential concentration and retention of radioactivity was recorded. In the anterior pituitary, hypothalamus, preoptic area and brain cortex, however, the maximum uptake was observed 7½ min after the injection of the hormone. Thereafter the radioactivity rapidly declined. Non-labelled testosterone was found to compete with the radioactive testosterone for the binding sites in the anterior pituitary, hypothalamus and preoptic area. High doses of non-labelled testosterone caused a slight, and statistically insignificant reduction of the radioactivity in the brain cortex. The concentration of radioactivity in the muscle tissue was not affected by any of the doses of non-radioactive testosterone given. Filtration of serum on Sephadex G-25 columns showed that considerable amounts of radioactivity were associated with macromolecules. Therefore in order to get a valid record of the binding of androgens to the specific molecules of the target cells, perfusion of the vascular system was essential. In vivo and in vitro experiments revealed that considerable amounts of radioactive material were bound to macromolecules in the cytosol fractions of the anterior pituitary gland, hypothalamus, preoptic area and brain cortex. Thus for the first time a binding of androgens by macromolecules in the cytosol fraction of the preoptic area and brain cortex has been found. Since association of androgens with plasma constituents can be excluded, the radioactive material is most likely bound to specific binding molecules present in the target cells of the anterior pituitary gland, hypothalamus, preoptic area and the brain cortex.

Degradation of Insulin-I131 by an Extract of Anterior Pituitary Gland

1958 ◽  
Vol 193 (3) ◽  
pp. 476-478 ◽  
Author(s):  
H. T. Narahara ◽  
R. H. Williams
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Trichloroacetic Acid ◽  
Electrophoretic Analysis ◽  
Anterior Pituitary Gland ◽  
Radioactive Material ◽  
Incubation Mixture ◽  
Pituitary Extract ◽  
Insulin Molecule

When insulin-I131 was incubated at 37°C and pH 7.5 with an extract of beef anterior pituitary, the radioactive material was rendered more soluble in trichloroacetic acid (TCA). Electrophoretic analysis of the TCA-soluble reaction product revealed that it was not free iodide. The concept that pituitary extract might contain a system capable of attacking the insulin molecule was strengthened by the observation that the addition of nonlabeled insulin to the incubation mixture decreased the rate of degradation of insulin-I131. The degradative system of beef anterior pituitary extract was found to be nondialyzable and heat-labile. The degradation of insulin by pituitary extracts may help to explain the observation of other workers that such extracts can inactivate insulin in vitro.

ANDROGEN RECEPTORS IN THE RAT BRAIN, ANTERIOR PITUITARY GLAND AND VENTRAL PROSTATE GLAND: EFFECTS OF ORCHIDECTOMY AND AGEING

1979 ◽  
Vol 81 (1) ◽  
pp. 75-81 ◽  
Author(s):  
B. D. GREENSTEIN
Keyword(s):  
Pituitary Gland ◽  
Binding Sites ◽  
Anterior Pituitary ◽  
Androgen Receptors ◽  
Prostate Gland ◽  
Anterior Pituitary Gland ◽  
Male Rats ◽  
Ventral Prostate ◽  
Binding Reaction ◽  
Old Rats

Available high-affinity binding sites for 5α-dihydrotestosterone (DHT) were measured in cytosols obtained from the amygdala, hypothalamus, anterior pituitary gland and ventral prostate gland of 12-week-old rats at various times after orchidectomy, and in the corresponding tissues of 18-month-old male rats. It is suggested that the lower affinity of the DHT binding reaction in brain and ventral prostatic cytosols after orchidectomy or ageing respectively, may explain, at least in part, the changes in the responsiveness of the tissues to androgens.

IMMUNOCHARACTERISTICS OF OESTROGEN AND ANDROGEN TARGET CELLS IN THE ANTERIOR PITUITARY GLAND OF THE CHICK EMBRYO AS DEMONSTRATED BY A COMBINED METHOD OF AUTORADIOGRAPHY AND IMMUNOHISTOCHEMISTRY

1980 ◽  
Vol 86 (2) ◽  
pp. 245-NP ◽  
Author(s):  
J.-M. GASC ◽  
M. SAR ◽  
W. E. STUMPF
Keyword(s):  
Chick Embryo ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Feedback Regulation ◽  
Anterior Pituitary Gland ◽  
Target Cells ◽  
Combined Method ◽  
Gonadotrophin Secretion ◽  
Positive Immunoreactivity ◽  
Autoradiographic Technique

The distribution of oestrogen and androgen target cells in the anterior pituitary gland of the chick embryo on days 10, 12 and 15 of incubation was studied 1 h after the injection of tritium-labelled steroid hormone using the thaw–mount autoradiographic technique. Oestradiol target cells were localized in the caudal zone that corresponds to the so-called 'caudal lobe', while androgen target cells were found throughout the rostral and caudal lobes of the anterior pituitary gland. With a combined autoradiography and immunohistochemistry technique, most of the oestrogen target cells showed immunoreactivity to turkey LH antiserum but not to adrenocorticotrophin (1–24) and β-thyrotrophin antisera. In contrast, androgen target cells did not show positive immunoreactivity to the three antisera used. The results suggested a direct and early involvement of oestrogens but not of androgens in the feedback regulation of pituitary gonadotrophin secretion in the chick embryo.

scholarly journals 60 YEARS OF NEUROENDOCRINOLOGY: MEMOIR: Harris' neuroendocrine revolution: of portal vessels and self-priming

2015 ◽  
Vol 226 (2) ◽  
pp. T13-T24 ◽  
Author(s):  
George Fink
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Anterior Pituitary Gland ◽  
Portal Blood ◽  
Endocrine Disorders ◽  
Experimental Proof ◽  
Chemical Substances ◽  
Major Interest ◽  
The Brain ◽  
Hypophysial Portal

Geoffrey Harris, while still a medical student at Cambridge, was the first researcher (1937) to provide experimental proof for the then tentative view that the anterior pituitary gland was controlled by the CNS. The elegant studies carried out by Harris in the 1940s and early 1950s, alone and in collaboration with John Green and Dora Jacobsohn, established that this control was mediated by a neurohumoral mechanism that involved the transport by hypophysial portal vessel blood of chemical substances from the hypothalamus to the anterior pituitary gland. The neurohumoral control of anterior pituitary secretion was proved by the isolation and characterisation of the ‘chemical substances’ (mainly neuropeptides) and the finding that these substances were released into hypophysial portal blood in a manner consistent with their physiological functions. The new discipline of neuroendocrinology – the way that the brain controls endocrine glands andvice versa– revolutionised the treatment of endocrine disorders such as growth and pubertal abnormalities, infertility and hormone-dependent tumours, and it underpins our understanding of the sexual differentiation of the brain and key aspects of behaviour and mental disorder. Neuroendocrine principles are illustrated in this Thematic Review by way of Harris' major interest: hypothalamic–pituitary–gonadal control. Attention is focussed on the measurement of GnRH in hypophysial portal blood and the role played by the self-priming effect of GnRH in promoting the onset of puberty and enabling the oestrogen-induced surge or pulses of GnRH to trigger the ovulatory gonadotrophin surge in humans and other spontaneously ovulating mammals.

GONADOTROPHIN SECRETION AFTER ELECTRICAL STIMULATION OF THE PREOPTIC AREA DURING THE OESTROUS CYCLE OF THE RAT

1974 ◽  
Vol 62 (3) ◽  
pp. 589-604 ◽  
Author(s):  
G. FINK ◽  
M. S. AIYER
Keyword(s):  
Electrical Stimulation ◽  
Luteinizing Hormone ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Preoptic Area ◽  
Medial Preoptic Area ◽  
Anterior Pituitary Gland ◽  
Oestrous Cycle ◽  
Early Afternoon ◽  
Stimulation Of

SUMMARY The responsiveness of the hypothalamo-hypophysial axis to electrical stimulation of the medial preoptic area was tested at various times during the oestrous cycle of the rat. Animals were anaesthetized with sodium pentobarbitone, and glass-insulated bipolar platinum electrodes were stereotaxically implanted in the medial preoptic area. The stimulus consisted of accurately balanced biphasic rectangular pulses, height 500 μA, duration 2 ms and frequency 60 Hz, applied in trains of 30 s intervals. The concentration of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in blood samples withdrawn from the external jugular vein immediately before and at frequent intervals up to 1 h after application of the stimulus was determined by radioimmunoassay. In all animals the stimulus was applied for a period of 15 min, for it was found that under these conditions the profiles of LH and FSH produced in individual animals were similar to those which followed the i.v. injection of 50 ng synthetic luteinizing hormone releasing factor (LH-RF)/100 g body wt, the minimal ovulatory dose of LH-RF in our laboratory. Both for LH and FSH, the profiles of responsiveness of the hypothalamo-hypophysial axis to electrical stimulation through the oestrous cycle resembled closely the profile of responsiveness of the anterior pituitary gland to LH-RF administered intravenously. There was a relatively gradual increase in pituitary sensitivity, in terms of the mean maximal increments, between the early afternoon of dioestrus and pro-oestrus, followed by an abrupt and marked rise which reached a peak at 18.00 and 21.00 h of pro-oestrus for LH and FSH, respectively. Sensitivity of the hypothalamo-hypophysial axis declined through oestrus and metoestrus reaching a nadir at 13.30 h of dioestrus. While these results do not exclude a change in sensitivity of the neural component of the hypothalamo-hypophysial axis during the oestrus cycle, they do indicate that the timing and magnitude of changes in sensitivity of the anterior pituitary gland to both endogenous and exogenous LH-RF are similar. This raises the possibility that a marked increase in the secretion of LH-RF during the afternoon of pro-oestrus may not be necessary for the occurrence of the surge of LH and FSH, for conceivably the latter could depend on a change in sensitivity of pituitary gonadotrophs to constant or only slightly increased levels of LH-RF in hypophysial portal blood. Our findings are compared with those of workers who have employed electrochemical stimulation of the preoptic area.

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