Role of the pineal gland in the regulation of prostatic androgen receptors in pubertal and mature rats

Abstract

The effects of exposure to continuous light, continuous darkness, and administration of melatonin on prostatic androgen receptors in relation to pubertal development in rats were examined. Darkness produced dissimilar results between the pubertal and adult groups. Whereas the prostate weight in the pubertal group remained unaltered, it increased in the adult group. In the pubertal group exposed to darkness, plasma melatonin increased significantly, and androgen receptors declined, whereas in the adult group these receptors rose significantly with a simultaneous increment of melatonin concentration in plasma. Exposure to continuous light did not produce any effective alterations in the parameters examined. The afternoon melatonin administration showed trends similar to those seen in animals exposed to darkness. The results indicate that exposure to darkness or administration of melatonin both have age-dependent effects on prostatic androgen receptors. Exposure to darkness may interfere with the process of sexual maturation in the pubertal animal as a result of increased melatonin production.

Ontogeny of the androgen receptor in rat ventral prostate during sexual development

“…These results convincingly demonstrate that the concentration of androgen receptors may also be regulated by mechanisms other than androgens or pituitary hormones. More recent findings provide evidence that the pineal [10] and dopamine [11] may be involved in the regulation of androgen receptor concentrations.…”

“…Cytosolic androgen receptor was analyzed according to Wagner [19] with the modifications of Moeller et al [8][9][10]. Briefly, the frozen tissue was powdered and suspended in 4 volumes of buffer (10 mM Tris-HC1, pH 7A, 0°C; 50 mM dithioerythritrol, 5 mM NAN3, 250 mM sucrose, 400 mU/ml NADase); i h centrifugation (100,000 g); incubation of supernatant for 24 h at 0°C with 20 nM 3H-DHT (final concentration) and additional 2 IxM R 1881 in parallel assays for identification of unspecifically bound 3H-DHT; separation of receptor-bound 3H-DHT by agar gel electrophoresis at low temperature [18].…”

Ontogeny, Circadian Rhythm Pattern, and Hormonal Modulation of 5α-Dihydrotestosterone Receptors in the Rat Pineal

“…However, while the prostatic receptors, espe cially those of the nucleus, decline after castration [ 12], the nuclear receptors of the pineal significantly in creased. Although the time lapse between orchidectomy and sacrifice was different for the two studies, it is hard to explain the anomalous behavior.…”

“…The cytosolic 5a-DHT receptor binding sites were measured as described by Moeller et al (II,12] following the method of Wagner [13] with the modification that 'H-DHT was sta bilized during incubation by addition of NAD+ nucleosidase; an other modification, which has been also earlier described by Haidar and Gupta [14], was the postincubation separation of free and bound ligands. Instead of agar gel electrophoresis, dextran-coated charcoal suspension was used throughout the current investigation.…”

“…The limit of detection was 4.0-fmol binding sites per milligram protein; the interassay coefficient of variation was 11.3%. Protein was as sayed by applying the method of Schaffner and Wissmann [15] with the modifications as reported by Moeller et al [12], DNA was as sayed in the 100,000 g pellet according to the method of Burton [ 16] using deoxyribose as standard. Correction was carried out by means of Spearman's coefficient rank correlation.…”