Influences of Photoperiod on Nuclear Androgen Receptor Occupancy in Neuroendocrine Tissues of the Golden Hamster

Bittman, Eric L.; Krey, L.C.

doi:10.1159/000124892

Cited by 27 publications

(30 citation statements)

References 41 publications

(54 reference statements)

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“…Washingtons Crossing, N.J.) anesthesia and main tained in LD photoperiod for 7 weeks. At this time the animals were anesthetized with ether, and a Silastic capsule (Dow-Coming 602-285, I cm long; ID: 0.062"; OF: 0.125") filled with crystalline Twas inserted s.c. to generate serum androgen concentrations (1.5 ng/m l) equivalent to those in intact males in a LD photoperiod (6). After capsule inser tion, half of the animals were transferred to SD photoperiod.…”

Section: Steroid Metabolism Studymentioning

confidence: 99%

“…The MBH and POA blocks were dissected as previously described [6]. The amygdala was dissected in 2-mm square blocks bounded medially by the optic tracks at the level of the MBH.…”

Section: Steroid Metabolism Studymentioning

confidence: 99%

“…An aliquot (300 pi) was removed from each sample to characterize the 3H steroids in the whole tissue. The remaining solutions were used to prepare a purified nuclear pellet by centrifugation (25,000 g at 4 °C) through 2 M sucrose [6].…”

Section: Steroid Metabolism Studymentioning

confidence: 99%

“…Specifically, short-day photoperiods of less than 12.5 h of light [ 15] markedly enhance T suppression of LH release [6,41,46]. This phenomenom appears to be mediated by the prolonged increase in pineal melatonin secretion characteristic of short days [3, 25,38] and may account for the regression of the testes observed under these lighting conditions [ 18].…”

mentioning

confidence: 99%

“…We have previously reported that cell nuclear androgen + receptor levels are comparable in the medial basal hypothala mus (MBH), preoptic area (POA) and anterior pituitary gland of male hamsters maintained in long-or short-day photope riods and exposed to constant circulating levels of androgen [6]. Similarly, Callard et al [9] have reported that limbic brain Received: January 9, 1989 Accepted after revision: March 17, 1989 (POA, MBH and amygdala) cell nuclear estrogen -f receptor levels associated with androgen treatments actually decrease when male hamsters are exposed to short days.…”

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confidence: 99%

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Effects of Daylength on Androgen Metabolism and Pulsatile Luteinizing Hormone Secretion in Male Golden Hamsters

Krey¹,

Ronchi²,

Bittman³

1989

Neuroendocrinology

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In an effort to understand the potential neuroendocrine mechanisms underlying photoperiodic control of fertility in seasonally breeding species, we monitored the intracellular processing and nuclear uptake of [1α,2α-³H]testosterone (³H-T) within the brain-pituitary complex as well as the patterns of episodic luteinizing hormone (LH) secretion in male golden hamsters exposed to long day (14 h light: 10 h dark) and short day (10 h light: 14 h dark) photoperiods. Target tissue specific patterns of nuclear ³H-androgens and estrogens were observed in castrated, T-replaced hamsters exposed to long and short days for 7 weeks or longer. Significantly, ³H-T metabolism or receptor-mediated nuclear uptake in the hamsters in short days was not influenced in any manner that would explain their increased responsiveness to androgen feedback suppression of LH release. Comparable patterns of episodic LH secretion were observed in acutely catheterized hamsters castrated for 7 weeks prior to exposure to 8 weeks of long or short days. Similar patterns were also observed in animals maintained in long days and castrated 1 or 2 weeks prior to blood collection. However, such a pattern was not seen in acutely castrated hamsters maintained in the short-day photoperiod. The data suggest that steroid-independent mechanisms play an important role in suppressing gonadotropin release in short days in this species. However, such mechanisms appear to be most effective when the animals are or have recently been exposed to circulating androgens.

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Section: Steroid Metabolism Studymentioning

confidence: 99%

“…The MBH and POA blocks were dissected as previously described [6]. The amygdala was dissected in 2-mm square blocks bounded medially by the optic tracks at the level of the MBH.…”

Section: Steroid Metabolism Studymentioning

confidence: 99%

Section: Steroid Metabolism Studymentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Effects of Daylength on Androgen Metabolism and Pulsatile Luteinizing Hormone Secretion in Male Golden Hamsters

Krey¹,

Ronchi²,

Bittman³

1989

Neuroendocrinology

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Distribution and hormonal regulation of androgen receptor immunoreactivity in the forebrain of the male European ferret

1996

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The distribution and hormonal regulation of androgen-receptor-immunoreactive (AR-ir) cells in the male European ferret forebrain were examined. AR-ir cells were found in many limbic and hypothalamic structures, and their distribution was similar to that reported for cells that either bind androgen or contain AR protein or mRNA in other species. Regulation of brain AR immunoreactivity by gonadal steroids was brain-region dependent. In most regions examined, including the preoptic area, amygdala, and several hypothalamic nuclei, castration reduced the density of AR-ir profiles and the intensity of immunocytochemical staining, and long-term (days) androgen, but not estrogen, replacement restored these parameters of AR immunoreactivity. Other areas, such as the bed nucleus of the stria terminalis, appeared to be relatively resistant to modulation of AR immunoreactivity by castration and long-term androgen treatment. The ability of testosterone to increase AR-ir profile density is not a simple consequence of translocation of AR from the cytoplasm to the nucleus, because short-term (hours) treatment with testosterone did not result in an increase in AR-ir profile density equivalent to that seen after 10 days of testosterone treatment. Thus, androgens appear to be able to increase AR levels within certain brain cell groups, thereby altering target tissue responsiveness to their own action.

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Intracellular partitioning of androgen receptor immunoreactivity in the brain of the male syrian hamster: Effects of castration and steroid replacement

Wood

Newman

1993

J. Neurobiol.

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The effect of castration and steroid replacement on the intracellular partitioning of the androgen receptor in the brain of the male Syrian hamster was determined using immunocytochemistry. Androgen receptors were visualized using the PG-21 antibody (G. S. Prins) on 40-microns coronal brain sections from hamsters perfused with 4% paraformaldehyde with or without 0.4% glutaraldehyde. Control studies confirmed antibody specificity in gonad-intact and castrate males. In the normal adult male, androgen receptor immunocytochemistry reveals intense staining confined to the cell nucleus. Castration caused a gradual increase in cytoplasmic labelling within 2 weeks, accompanied by a reduction in nuclear staining intensity in androgen receptor-containing neurons throughout the brain. Cytoplasmic androgen receptor staining was eliminated after treatment of orchidectomized males for only 8 h with exogenous testosterone. Likewise, long-term exposure to testosterone and dihydrotestosterone, a nonaromatizable androgen, maintained nuclear androgen receptor immunoreactivity. However, exposure to low physiologic concentrations of estrogen was not effective in this regard. In addition, we determined that nuclear androgen receptor immunoreactivity decreases in response to inhibitory short-day photoperiod, but without an increase in cytoplasmic immunostaining. This appears to be due to the decrease in androgen production by the testis, rather than a direct photoperiodic effect, because testosterone supplementation to short-day males restored the intensity of nuclear androgen receptor immunoreactivity to levels comparable to those in the intact male. These findings are compatible with a new model for the intracellular localization of androgen receptors, in which a subset of unoccupied receptors is located in the cell cytoplasm in the absence of ligand. They further demonstrate the repartitioning of such cytoplasmic receptors, thereby confirming and extending previous observations using biochemical techniques on the regulation of neuronal androgen receptors.

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Influences of Photoperiod on Nuclear Androgen Receptor Occupancy in Neuroendocrine Tissues of the Golden Hamster

Cited by 27 publications

References 41 publications

Effects of Daylength on Androgen Metabolism and Pulsatile Luteinizing Hormone Secretion in Male Golden Hamsters

Effects of Daylength on Androgen Metabolism and Pulsatile Luteinizing Hormone Secretion in Male Golden Hamsters

Distribution and hormonal regulation of androgen receptor immunoreactivity in the forebrain of the male European ferret

Intracellular partitioning of androgen receptor immunoreactivity in the brain of the male syrian hamster: Effects of castration and steroid replacement

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