In addition to physiological functions, the neuropeptide hormone, arginine vasopressin (AVP) facilitates the mammalian central nervous system (CNS) regulation of cognitive function and social behaviors. V 1A receptors mediate these effects. Although distribution patterns of AVP-producing neurons and fibers are similar among mammals, CNS V1A receptor patterns are species-specific.
Here, rhesus (Macaca mulatta) central V1A receptors were mapped using receptor autoradiography techniques. By incubating 20 μm tissue sections with 125I-lin-AVP (125I-Phenylacetyl-D-Tyr(Me)-Phe-Gln-Asn-Arg-Pro-Arg-Tyr-NH 2 linear vasopressin V1A receptor antagonist) AVP binding sites were detected. A V1A agonist ([d(Ch2)5[Tyr(Me)]AVP) displaced the 125I-lin-AVP tracer in all sites, providing support for verification of the sites as V1A receptors.
V1A receptors were localized within pyriform, entorhinal, cingulate and insular cortices, the presubiculum, bed nucleus of the stria terminalis (BNST), lateral septum (LS), mammillary bodies and within several structures of the amygdala, hypothalamus, hippocampus, thalamus and brain stem.
The rhesus V1A receptor map is relevant to recent research in human learning, memory and emotion. Particularly pertinent are those receptors found in the amygdala, mammillary bodies, medial temporal lobe structures, and cingulate cortex.
Comparison of this rhesus V1A receptor map to those previously reported for nonprimates revealed that all had V1A receptors in the BNST, central amygdala, diagonal band of Broca, LS, and solitary tract. Marmosets shared similar binding patterns in the BNST, but densities differed in SCN, LS, and various amygdala and hypothalamus regions. In presubiculum, supraoptic nucleus, cortical regions, and mammillary bodies, areas dense with V1A receptors in rhesus, marmosets revealed none. Such differences may reflect species-specific memory capabilities.