Meeting Abstract

63.2  Friday, Jan. 6  Social Isolation, Reproductive Physiology and Behavior in Male Zebra Finches ERNST, D.F.K.*; BENTLEY, G.E. ; UC Berkeley

Zebra finches are not highly photoperiodic and instead respond to environmental cues such as rainfall, food availability, and social cues to time reproduction. Unlike many photoperiodic species, zebra finches do not exhibit marked changes in hypothalamic GnRH-I content in different reproductive conditions. Instead, it is thought that regulation of the hypothalamo-pituitary-gonadal (HPG) axis occurs via regulation of GnRH-I release at the level of the median eminence. Type II iodothyronine deiodinase (DIO2) has been implicated in the rapid release of GnRH-I from the hypothalamus in photoperiodic species in response to a stimulatory cue. Thus, we hypothesized a role for DIO2 in zebra finch HPG activation in response to stimulatory social cues. We predicted that social isolation would cause downregulation of the HPG axis, and that subsequent presentation of a novel female would rescue this effect. Following two days of social isolation males were presented with a novel female, a novel male, or no stimulus. Males presented with a female exhibited increased activity, courtship and mating behavior compared with males in the other two groups. One hour following the behavioral assay, RNA was extracted from the brains for qPCR, and sections of the brain were retained for ICC. There were no differences in expression of genes for DIO2, DIO3, GnRH, GnIH, or CFOS in the hypothalamus, while the group of males presented with a female had significantly greater EGR-1 expression than the isolated group (p<.03). Males given a male conspecific had an intermediate amount of EGR-1 expression. ICC results show that EGR-1 was not co-localized with GnRH-I neurons. These data indicate a social effect on behavior and EGR-1 expression in the hypothalamus of males, but this effect does not appear to influence components of the HPG axis directly.