Description and comparison of brain distribution of oxytocin receptors in Rhabdomys pumillio and Rhabdomys dilectus

• Published in: General and comparative endocrinology Vol. 335; p. 114224
• Main Authors: Olazábal, D.E., Pillay, N., Sandberg, N., Hartman, K.-J.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-05-2023
• Subjects: Animals; Brain - metabolism; Comparative anatomy; Female; Hypothalamus - metabolism; Male; Oxytocin; Oxytocin - metabolism; Preoptic Area - metabolism; Receptors, Oxytocin - metabolism; Rodent; Rodentia - metabolism; Social behavior; Social behavior; Comparative anatomy; Oxytocin; Rodent
• ISSN: 0016-6480; 1095-6840
• DOI: 10.1016/j.ygcen.2023.114224

•R. pumilio and R. dilectus have low OXTR density in septum and nucleus accumbens.•R. pumilio has higher density of OXTR in LS and BNST.•R. dilectus has higher density of OXTR in NA, DB, MPOA, Lh, PAG, PVA.•Sex differences in the regulation of OXTR differs in these two species.•Findings are typical of non-monogamous species occurring in variable population sizes.
Oxytocin receptor (OXTR) distribution in the brain has been associated with different reproductive and social strategies of species. Rhabdomys pumilio (R. pumilio) and Rhabdomys dilectus (R. dilectus) are two sister rodent species that live in large/medium (but flexible) or small (mostly solitary) social groups respectively. In this study, we describe and compare the distribution of OXTR in these two species. OXTR binding in the brain of R. pumilio (8 females and 5 males) and R. dilectus (8 females and 5 males) adults was determined using autoradiography. Our results revealed significant differences in the nucleus accumbens, diagonal band, medial preoptic area, lateral habenula, superior colliculus, periaqueductal area and anterior paraventricular nucleus (higher in R. dilectus), and the dorsal lateral septum and anterior bed nucleus of the stria terminalis (higher in R. pumilio). OXTR density in other brain regions, such as the amygdala nuclei and hippocampus, did not differ between the two species. Sex differences were found in the medial preoptic area and ventral region of the lateral septum in R. pumilio (OXTR density higher in males) and in the anterior paraventricular thalamic nucleus, ventromedial nucleus of the hypothalamus and basolateral amygdala of R. dilectus (OXTR density higher in females). A sex difference in the density of OXTR was also found in the posterior region of the bed nucleus of the stria terminalis, where it was higher in males than in females of both species. This study shows species-specific brain distribution of OXTR in R. pumilio and R. dilectus that are unique, but with similarities with other polygynous or promiscuous rodent species that live in variable size groups, such as R. norvergicus, C. sociabilis, S. teguina and M. musculus.