SPECIES AND SEX DIFFERENCE IN THE CORRELATION VASOPRESSIN V1A AND OXYTOCIN RECEPTOR DENSITY IN THE BRAIN OF <EM>RHABDOMYS PUMILLIO</EM> AND <EM>RHABDOMYS</EM> <EM>DILECTUS</EM>

Vasopressin receptor 1A (V1aR) and oxytocin receptor (OXTR) distribution in the brain has been extensively studied because of the role of vasopressin (AVP) and oxtocin (OXT) in regulating aggressiveness, stress responses, reproductive and social behavior, among other functions. Rhabdomys pumilio (R. pumilio) and Rhabdomys dilectus (R. dilectus) are two sister rodent species that differ in their aggressiveness, anxiety, stress, and size of their social groups. In this study, we describe and compare the correlation between V1aR and OXTR density in the brain of these two species. V1aR and OXTR binding in the brain of R. pumilio (7 females and 5 males) and R. dilectus (7 females and 5 males) adults was determined using autoradiography. Our study showed species-specific brain distribution of V1aR and OXTR in R. pumilio and R. dilectus. Positive and negative correlations between V1aR and OXTR density were found in several brain regions relevant for social behavior, reward, and stress. However, those correlations were also species-specific. The correlation between these two peptide receptors also differed between male and female R. pumilio. Therefore, AVP and OXT systems can interact differently depending on the brain region, sex and species studied. Therefore, the translation of findings related to OXT/AVP system interaction and regulation need to be done carefully and considering these differences.