Arginine vasotocin immunoreactivity in hypothalamic and extrahypothalamic areas of an amphibian brain

The distribution of arginine vasotocin immunoreactivity (irAVT) was investigated in the brain of male rough-skinned newts (Amphibia: Taricha granulosa) using microdissection and radioimmunoassay techniques. The highest levels of irAVT were observed in the neuroendocrine hypothalamo-hypophysial system. However, detectable quantities of irAVT (greater than 0.40 ng/mg protein) also were observed in extrahypothalamic areas such as pallium, amygdala, striatum and thalamic, tectal and brainstem nuclei. No irAVT was detected in the olfactory bulb, rostral telencephalon, or in specific areas of the caudal telencephalon and diencephalon. These results indicate that, in amphibians, AVT is distributed among a wide range of brain areas and that there is regional specificity in irAVT concentrations.