Meeting Abstract

P3.198  Monday, Jan. 6 15:30  Neuronal Plasticity in the Forebrain of the Male Checkered Garter Snake: Effect of Sex Steroid Hormones on Dendritic Spine Formation PATEL, N.T.*; KROHMER, R.W.; Saint Xavier University, Chicago, IL; Saint Xavier University, Chicago, IL krohmer@sxu.edu

In many seasonally breeding species, changes in the density and/or morphology dendritic spines appears to be an active process within neural regions essential for the control of reproductive behaviors. In many cases, this neuronal plasticity has been found to be in response to changes in circulating sex steroid hormone levels. Previous studies in the red-sided garter snake found a seasonal response in dendritic spine formation as well as changes in dendritic spine density in response to circulating levels of sex steroid hormones, with dendritic spine formation greater under the influence of estrogen compared to testosterone. The current study examines the role of sex steroid hormones on the density and morphology of dendritic spines within regions shown to be critical for the regulation of reproductive behaviors in the male checkered garter snake (Thamnophis marcianus). Our study revealed that animals receiving either testosterone or estradiol exhibited greater density of dendritic spines than control animals. However, animals implanted with estrogen exhibited greater dendritic spines density compared to testosterone implanted animals. These results add to the increasing amount of evidence suggesting that estrogens, aromatized from circulating testosterone may be the active hormone setting up the pathways critical for the regulation of reproductive activity in a reptile.