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Neuroscience & Behavior
Master of Science (M.S.)
Year Degree Awarded
Month Degree Awarded
Trio, AVPV, TCDD, sexual dimorphism, splice variants
The anteroventral periventricular nucleus (AVPV) is a sexually dimorphic preoptic structure that is nearly three times larger in the female rat. Estradiol (E2) exposure during development decreases AVPV volume through apoptosis, a process which normally occurs preferentially in male. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is an endocrine disrupter that interferes with E2-dependent sexual differentiation of the AVPV. Whole-genome microarrays were used to identify sex-specific genes regulated by E2 and TCDD in postnatal day 2 (P2) AVPV punches from untreated males and females, males treated with TCDD or vehicle, and females treated with E2 or vehicle. Trio emerged as a gene target regulated by E2 and TCDD, and this gene is essential for neurite outgrowth which is sexually dimorphic in the AVPV. My goal was to verify microarray data that Trio was expressed in the P2 AVPV and to test whether expression was affected by sex, E2 and TCDD. The microarray did not discriminate among Trio splice variants, 9S, 9L and Duet, so I mapped each of these in the P2 AVPV using in situ hybridization. I used quantitative real-time PCR to examine the effects of sex, E2 and TCDD on mRNA levels encoding each splice variant. I found that the AVPV expressed 9S and 9L at moderate levels and Duet at low levels. The expression of 9S and 9L mRNA was increased by E2 in females. However, only 9S expression differed between sexes and it was lower in males. TCDD had no effect on expression of any of the splice variants. This work provides the first evidence that Trio splice variants are independently regulated and that Trio may mediate effects of E2 in the developing AVPV.
Sandra L Petersen