BEHAVIORAL-ASSESSMENT OF PINEALECTOMY AND FETAL PINEAL-GLAND TRANSPLANTATION IN RATS .2.

Pineal gland is an endocrine organ which exerts regulatory effects on the activity of various organs and systems. The present study was unde rtaken to highlight in experimental animals the possible integrative f unction of this endocrine organ on a behavioural pattern. Pinealectomy and foetal pineal gland transplantation to a subpial cortical area cl ose to the pinealectomized region was performed. Behaviour was defined through motor activity induced by low (2 mg/kg) and high (10 mg/kg) d oses of amphetamine in rats. It was shown that pinealectomy produced s ignificantly different patterns of behaviour induced by low and high d oses of amphetamine. In sham operated animals low dose amphetamine ind uced a significant locomotor stimulation but without stereotyped activ ity. High dose amphetamine induced stereotyped activity. After pineale ctomy even low dose amphetamine produced the behavioural pattern of st ereotyped activity resembling a high dose amphetamine-induced behaviou r. This differential effect of amphetamine, seen in pinealectomized ra ts, was completely restored after transplantation. On the other hand, melatonin treatment did not generate a significant alteration of behav ioural profile either in the control or pinealectomized group of rats. Results are discussed with regard to the general regulatory function of the pineal gland.