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Environmental Impact on Puberty and Reproductive Function

Principal Investigator: Dr. Greg Fraley

Research in my laboratory tests the hypothesis that environmental factors associated with food availability modulate the development of adult reproductive function. In female animals, puberty and reproduction can be prevented by small changes in food availability, whereas males appear to be less susceptible. It is plausible that environmental factors such as the time of weaning, food availability, or food type (fat vs. protein vs. carbohydrate) alter neural mechanisms that regulate puberty and reproduction. The neural mediator between nutritional status and reproduction is not known. Galanin-like peptide (GALP), appears to have a primary role in the regulation of reproduction; furthermore, GALP gene activity is solely regulated by metabolic signals. GALP may be an important mediator between nutrition and reproduction, and thus a central target for metabolic
signals that are responsible for governing the timing of the onset of puberty. The aims of my research are to 1) to determine the effects of altered nutritional environments alter the ontogeny of GALP gene expression, 2) to determine the role of hypothalamic GALP in regulating reproductive development, and 3) to understand the neural mechanisms underlying the sex differences in the timing of the onset of puberty. Students in my laboratory participate in all aspects of research: development of hypotheses, experimental design, data acquisition, data analysis, and scientific writing. Students combine behavioral, histological and molecular biological approaches to understand how internal and external environmental factors alter biological systems involved with reproductive development. This combination of techniques illustrates to trainees the interdisciplinary aspects to neuroscience.

Representative Publications:

  • Fraley, G. S. 2006. Immunolesions of glucoresponsive projections to the arcuate nucleus alter glucoprivic-induced alterations in food intake, luteinizing hormone secretion, and GALP mRNA but not sex behavior in adult male rats. Neuroendocrinology. 83: 97-105.
  • Stoyanovich, A. G.*, Johnson, M. A.*, Clifton, D. K., Steiner, R .A. and Fraley, G. S. 2005. Galanin-like peptide rescues reproductive function in the diabetic rat. Diabetes. 54: 2471-2476.
  • Kauffman, A. S., J. Buenzle, G S. Fraley, and E .F. Rissman. 2005. Effects of galanin-like peptide (GALP) on locomotion, reproduction, and energy balance in female mice. Hormones and Behavior. 48(2):141-151.
  • Fraley, G. S., S. E. Thomas-Smith, B. Acohido, D. K. Clifton, and R. A. Steiner. 2004. Stimulation of Sexual Behavior in the Male Rat by Galanin-Like Peptide. Hormones and Behavior 46: 551-557.
  • Fraley, G. S., I. Shimada, D. Teklemichael, J. Scarlett, D. K. Clifton, and R. A. Steiner. 2004. The effects of insulin and diabetes on hypothalamic galanin-like peptide mRNA. Diabetes 53: 1237-1242.
  • Hansen, K. R., S. M. Krasnow, M. A. Nolan, G. S. Fraley, J. W. Baumgartner, D. K. Clifton, and R. A. Steiner. Activation of the sympathetic nervous system by galanin-like peptide - a possible link between leptin and metabolism. Endocrinology 144: 4709-4717.
  • Fraley, G. S., I. Shimada, J. Baumgartner, D. K. Clifton, R. A. Steiner. 2003. Differential fos induction in the hypothalamus following intracerebroventricular injection of galanin-like peptide. Endocrinology 144(4): 1143-1146.
  • Krasnow, S. M., G. S. Fraley, S. M. Schuh, J. W. Baumgartner, D. K. Clifton and R .A. Steiner. 2003. A Role For Galanin-like Peptide (GALP) in the integration of feeding, body weight regulation and reproduction in the mouse. Endocrinology 144(3): 813-822.

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