Domestication alters 5-HT1A receptor binding in rat brain.

Serotonin-1A receptor binding density was compared in the brains of wild and domesticated adult male Rattus norvegicus using in vitro receptor autoradiography of [3H]8-hydroxy-2-[n-dipropylamino]tetraline (DPAT). While both groups exhibited similar patterns of labeling, [3H]DPAT binding density was significantly (p less than or equal to 0.05) lower in the median raphe nucleus and greater in superficial entorhinal cortex and rostral dentate gyrus of domesticated compared to wild rats. The results suggest that specific serotonergic circuits from the median raphe nucleus to the entorhinal and hippocampal regions might be involved in regulation of the defensive behaviors that differ profoundly between wild and domesticated rats. The relationship of these putative differences to behavioral disorders such as anxiety and depression in humans is discussed.