Vasopressin- and oxytocin-like systems in the chameleon brain.

The distribution of vasopressin (VP)-like and oxytocin (OX)-like immunoreactivities was investigated in the chameleon brain with antisera specific for either peptide. VP-like and OX-like neurons are found only in two nuclei: in the supraoptic and in the paraventricular nuclei, whereas both peptidergic innervations are restricted to some ventral areas, especially to the hypothalamus. However, in these areas, OX-like innervation is less dense than the VP-like innervation. Even though, no sex differences were noted for the two systems, differences are present between the normal female and the preoviposit one concerning VP-like system. In the latter female, numerous VPergic-like cell bodies occurred in the ependymal layer, making likely direct contact with the cerebrospinal fluid (CSF) of the third ventricle. In addition, some VP-like nerve fibers seem to be in supraependymal position at the septal wall, probably also in contact with CSF.