Many vertebrate species display seasonal changes in gonadotropin secretion, sexual behavior, and body weight. The effects of gonadal steroid hormones upon these functions vary with time of year. Fluctuations in daylength provide the proximate environmental cue which triggers these changes, and the photoperiodic signal is relayed to the neuroendocrine brain by the pineal gland. These phenomena are exemplified in the golden hamster, which will be the subject of the proposed research. The neurochemical mechanisms which are responsible for pineal-mediated changes remain poorly understood. Responsiveness to opiate agonists and antagonists depends upon photoperiod, however, and daylength may influence the concentration of neuropeptides including endogenous opiates. Daylength may influence respon- siveness to gonadal steroid hormones by regulating the expression of the genes which encode them in specific brain regions. The proposed experiments will utilize in vitro receptor autoradiography to determine the interaction between daylength and gonadal steroids in the regulation of opiate receptors, and establish the role of the pineal gland in these effects. The quantity and localization of mu, delta, and kappa receptors will be examined under different photoperiodic and steroidal conditions. The influence of these manipulations on the pattern of immunostaining of beta endorphin, met-enkephalin,and dynorphin will also be studied. Opiate peptide, androgen and estrogen receptor gene expression will be quantified in specific loci using in situ hybridization. Loci at which opiates regulate male sexual behavior will be examined by systemic and intracranial application of opiate receptor agonists and antagonists. In separate experiments on female hamsters, the neurochemical basis of photoperiodic influences on the induction of sexual receptivity will be examined by study of the interaction between estradiol and daylength in the regulation of oxytocin and GABA-a receptors. By manipulating photoperiod and gonadal steroid concentrations, we will determine the role of endogenous opiates in the integration of internally and externally generated signals. This will contribute to our understanding of the role of specific neuropeptides in the coordination of endocrine and behavioral processes, elucidate environmental and hormonal influences on CNS function, expand our knowledge of brain plasticity, and indi- cate controls over responsiveness to opiates relevant to abuse and addiction.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Scientist Development Award - Research (K02)
Project #
1K02MH000914-01A1
Application #
3070285
Study Section
Research Scientist Development Review Committee (MHK)
Project Start
1992-09-01
Project End
1997-08-31
Budget Start
1992-09-01
Budget End
1993-08-31
Support Year
1
Fiscal Year
1992
Total Cost
Indirect Cost
Name
University of Massachusetts Amherst
Department
Type
Schools of Arts and Sciences
DUNS #
153223151
City
Amherst
State
MA
Country
United States
Zip Code
01003
De La Iglesia, H O; Blaustein, J D; Bittman, E L (1999) Oestrogen receptor-alpha-immunoreactive neurones project to the suprachiasmatic nucleus of the female Syrian hamster. J Neuroendocrinol 11:481-90
Meyer-Bernstein, E L; Jetton, A E; Matsumoto, S I et al. (1999) Effects of suprachiasmatic transplants on circadian rhythms of neuroendocrine function in golden hamsters. Endocrinology 140:207-18
Bittman, E L; Tubbiola, M L; Foltz, G et al. (1999) Effects of photoperiod and androgen on proopiomelanocortin gene expression in the arcuate nucleus of golden hamsters. Endocrinology 140:197-206
Vernadakis, A J; Bemis, W E; Bittman, E L (1998) Localization and partial characterization of melatonin receptors in amphioxus, hagfish, lamprey, and skate. Gen Comp Endocrinol 110:67-78
Huang, L; DeVries, G J; Bittman, E L (1998) Photoperiod regulates neuronal bromodeoxyuridine labeling in the brain of a seasonally breeding mammal. J Neurobiol 36:410-20
Powers, J B; Jetton, A E; Mangels, R A et al. (1997) Effects of photoperiod duration and melatonin signal characteristics on the reproductive system of male Syrian hamsters. J Neuroendocrinol 9:451-66
Matsumoto, S; Basil, J; Jetton, A E et al. (1996) Regulation of the phase and period of circadian rhythms restored by suprachiasmatic transplants. J Biol Rhythms 11:145-62
Bittman, E L; Jetton, A E; Villalba, C et al. (1996) Effects of photoperiod and androgen on pituitary function and neuropeptide staining in Siberian hamsters. Am J Physiol 271:R64-72
de la Iglesia, H O; Blaustein, J D; Bittman, E L (1995) The suprachiasmatic area in the female hamster projects to neurons containing estrogen receptors and GnRH. Neuroreport 6:1715-22
Tubbiola, M L; Bittman, E L (1994) Steroidal and photoperiodic regulation of opiate binding in male golden hamsters. J Neuroendocrinol 6:317-22

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