| Abstract No.: | A-G1184 |
| Country: | Canada |
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| Title: | FLUCTUATIONS OF GAD65 MRNA IN THE CEREBELLUM OF MALE RATS DURING THE ACQUISITION OF SEXUAL EXPERIENCE. |
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| Authors/Affiliations: | 1 Laura Bolivar-Duarte*; 2 Milagros Silva; 2 Jorge Manzo; 1 James Pfaus;
1 Concordia University, Montreal, QC, Canada; 2 Universidad Veracruzana, Xalapa, Mexico. |
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| Content: | Sexually-naïve male rats typically take longer to initiate copulatory contact, display more incomplete mounts or mounts without intromission, and take longer to ejaculate, relative to sexually-experienced rats. It takes male rats several copulatory trials with ejaculation to reach stable individual baseline rates of sexual responding. Although very little is understood about how sexual behavior becomes habitual or “automated”, sexually- experienced males have a number of morphological and functional differences in their brains relative to sexually-naïve males, including a higher number of dendritic spines on medium spiny neurons in the nucleus accumbens, larger stimulated dopamine release in mesolimbic dopamine terminals, and higher oxytocin receptor densities in the ventromedial hypothalamus and medial amygdala. The cerebellum appears to play a critical role in the automation of behavioral responses, or “habits”, and previous work has revealed a pattern of Fos activation in granule cells of the mid-vermis and lobule 7 following a male rat’s first ejaculation that is inhibited after successive ejaculations. This inhibition suggested the activation of GABA neurons, therefore the present study quantified mRNA of the GABA synthesizing enzyme GAD65 by RT-PCR in the cerebellum of sexually naïve male rats following one, two, three, or four sessions of sexual behavior, each terminated after the first ejaculation. The cerebellum of each animal was divided into the vermis and hemisphere. A low concentration of GAD65 mRNA was found in both regions of sexually naïve, noncopulated control rats. However, during the acquisition of sexual experience, GAD65 mRNA concentrations in the hemispheres increased linearly after the first, second, and third training sessions, but returned to “naïve” levels after the fourth session, concomitant with the males acquiring baseline rates of copulatory behavior. These data suggest that GABA synthesis in the cerebellum follows a dynamic pattern of activation during the acquisition of baseline sexual behavior. GABA transmission in the cerebellum may therefore play an important role in motor learning, perhaps as a mechanism that inhibits out unnecessary movements in the formation of relatively “fixed” habits. |
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