Meeting Abstract

72.3  Friday, Jan. 6  Neural androgens regulate paternal care in a polygamous sex changing fish PRADHAN, DS*; SOLOMON-LANE, TK; WILLIS, MC; GROBER, MS; Georgia State Univ., Atlanta; Georgia State Univ., Atlanta; Georgia State Univ., Atlanta; Georgia State Univ., Atlanta

In many vertebrates, changes in circulating androgens regulate critical aspects of the breeding season. In species with considerable temporal overlap in territory defense, mating, and parental care, mechanisms of androgen action and effect are unclear. Lythrypnus dalli, a hermaphroditic fish, exhibits a haremic social structure where the male provides all parental care, including fanning and rubbing eggs until hatching, and aggressive defense of the nest/eggs from females and other predators. While there are no sex differences in systemic, brain, or gonadal 11-Ketotestosterone (KT), brain levels are several-fold higher than gonad, and parenting males have high systemic KT compared to non-parenting males. To test the hypothesis that brain KT regulates male parenting behavior, we intracerebroventricularly (icv) injected parenting males with either carbenoxolone (CBX), a KT synthesis inhibitor that does not cross the blood brain barrier, or vehicle. After icv injections, males were allowed to recover until they regained equilibrium and reunited with their harem for 1 h. CBX-treated males took longer to enter and defend their nest and had lower rates of parental care compared to controls. Females from groups with CBX treated males were also successful at entering the nest and consuming eggs. There were no overall differences in agonistic social behavior between the two groups. We will determine to what extent icv CBX manipulations affected KT levels in brain and other tissues of the experimental subjects. This is the first study to demonstrate that KT is necessary to regulate parental behavior in males. The use of an enzyme inhibitor (CBX) demonstrates that KT can be regulated non-genomically and thus rapidly.