Meeting Abstract

47.9  Jan. 6  Steroidogenic capacity of the Atlantic stingray (Dasyatis sabina) brain NOEL, M. L.*; NUNEZ, B.S.; Univ. of Texas Marine Science Institute; Univ. of Texas Marine Science Institute noelml@mail.utexas.edu

We investigated the steroidogenic capacity of the Atlantic stingray (Dasyatis sabina) brain by examining the expression of steroidogenic genes in six sections of the brain (cerebellum, telencephalon, optic lobe, medulla, hypothalamus and pituitary). Complementary DNA (cDNA) sequences specific for D. sabina steroidogenic factor-1 (SF-1), side chain cleavage (SCC), steroidogenic acute regulatory protein (StAR) and 11β-hydroxylase (11β-OH) were determined through a nested primer strategy with degenerate primers derived from teleost sequences. Aromatase and 3β-hydroxysteroid dehydrogenase (3β-HSD) sequences for the Dasyatis genus were taken from the literature (Ijiri et al., 2000 and Nunez and Trant, 1998, respectively). Primers specific for these cDNAs were used in RT-PCR to determine if their corresponding mRNAs are present in D. sabina brain from unstressed and stressed adult stingrays (disc width > 30 cm). Between both sexes and stress states, each of the genes investigated was present in at least one area of the brain, with usually more than one gene being present in a specific brain region. Unstressed females expressed three of the six genes investigated (StAR, aromatase, and 11β-OH) in brain tissue, while stressed female brain tissue expressed all six genes. Stressed and unstressed males expressed all genes investigated, though the distribution of expression was different depending on the animals� stress condition. In general, stressed animals expressed steroidogenic genes in more tissues than unstressed animals. This study suggests that the brain of the D. sabina is capable of steroidogenesis, and that stress may play an important role in regulating steroidogeneic gene expression, though further work is needed to determine the types of neurosteroids produced.