The experiments proposed here will determine the influences of time of day and daylength on the distribution and concentrations of opiate receptors in the brain of the male golden hamster, a photoperiodic seasonal breeder, Autoradiographic methods will be used to determine the quantity and localization of mu, delta, and kappa receptors. Since radioimmunoassays indicate large effects of photoperiod on the concentrations of endogenous opiates and since peptide and receptor distributions are not always matched, we will complement these binding experiments with immunocytochemical studies of the distribution of met- enkephalin, beta-endorphin, and dynorphin in the brains of long and short day hamsters. finally, the functional significance of opiates in seasonal changes in gonadotropin secretion, male sexual behavior, and body weight will be evaluated using brain lesions and the systemic and intracranial application of opiate receptor agonists and antagonists. By manipulating photoperiod and gonadal steroid concentrations, we will determine the role of endogenous opiates in the integration of internally and externally generated signals. These studies will contribute to our understanding of the role of specific neuro-peptides in the coordination of endocrine and behavioral processes, elucidate environmental and hormonal influences on CNS function, uncover mechanisms of reproductive cyclicity which have possible applications to human and animal fertility, expand our knowledge of brain plasticity, and indicate naturally occurring controls over responsiveness to opiates and hormones which may bear implications for syndromes of abuse and addiction.

National Institute of Health (NIH)
National Institute of Mental Health (NIMH)
Research Project (R01)
Project #
Application #
Study Section
Neurosciences Research Review Committee (BPN)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Massachusetts Amherst
Schools of Arts and Sciences
United States
Zip Code
Bae, H H; Mangels, R A; Cho, B S et al. (1999) Ventromedial hypothalamic mediation of photoperiodic gonadal responses in male Syrian hamsters. J Biol Rhythms 14:391-401
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
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
Tubbiola, M L; Bittman, E L (1995) Short days increase sensitivity to methadone inhibition of male copulatory behavior. Physiol Behav 58:647-51
Tubbiola, M L; Bittman, E L (1994) Steroidal and photoperiodic regulation of opiate binding in male golden hamsters. J Neuroendocrinol 6:317-22
Bittman, E L; Thomas, E M; Zucker, I (1994) Melatonin binding sites in sciurid and hystricomorph rodents: studies on ground squirrels and guinea pigs. Brain Res 648:73-9
Bittman, E L; Weaver, D R (1990) The distribution of melatonin binding sites in neuroendocrine tissues of the ewe. Biol Reprod 43:986-93