Enkephalin ( enk ) is one of endogenous opiate like substance and could induce psychological euphoria and modulate function of learning and memory . however there has no report available about the role of enk in acquisition of sprague - dawley rats as materials 脑啡肽( enk )是内源性阿片样物质的一种，可参与情绪反应调节，引起精神欣快感，并对学习记忆具有调制作用。
