Effects of amine pretreatment on ketamine catatonia in pinealectomized or hypophysectomized animals

The present studies were designed to clarify the role of catecholamines and pineal idolamines on ketamine-induced catatonia in the intact, pinealectomized or hypophysectomized chick and rat. In the pinealectomized chick, pretreatment with dopamine increased the duration of catatonia (DOC) after ketamine, but pretreatment with norepinephrine did not. The pineal indolamines exhibited mixed actions. Serotonin and N-acetyl serotonin which augmented ketamine DOC, did not do so in the absence of the pineal gland, whereas melatonin potentiated the ketamine DOC in both the intact and pinealectomized chick. Ketamine was more potent in the hypophysectomized chick and the circadian rhythm noted in the intact chick was absent; furthermore, melatonin did not augment the ketamine DOC whereas dopamine continued to do so. This study did not demonstrate a species difference regarding the role of the amines on the pineal in spite of the immature blood-brain barrier in the young chick and the intact barrier in the rat. In addition, these data indicate a direct role of the pituitary in the augmentation of ketamine DOC induced by melatonin. Furthermore, dopamine appeared to act on systems more closely involved with the induction of ketamine catatonia rather than directly on the pituitary.