Induction of the Zenk protein after sexual interactions in male Japanese quail.

We mapped cells immunoreactive (ir) for the protein encoded by the immediate early gene zenk in the brains of male Japanese quail after they engaged in either appetitive or consummatory sexual behavior (i.e. copulation). Castrated males treated with testosterone were either allowed to copulate with a female or exhibited a learned social proximity response indicative of appetitive sexual behavior, and were compared with control males in their home cage or in the experimental chamber but not exhibiting the proximity response. Copulation increased the number of ZENK-ir cells in the nucleus striae terminalis and the nucleus intercollicularis, while both copulation and the proximity response induced increases in the medial and anterior ventral hyperstriatum. These results indicate that zenk is induced in the context of sexual behavior.