COMPRESSION OF THE PITUITARY-STALK ELICITS CHRONIC INCREASES IN CSF VASOPRESSIN, OXYTOCIN AS WELL AS IN SOCIAL-INVESTIGATION AND AGGRESSIVENESS

The neurochemical and behavioural effects of a novel stereotaxic surgi cal method developed for interrupting the nerve fibres running through the rat pituitary stalk to the posterior pituitary gland was studied, The cerebrospinal fluid (CSF) vasopressin (AVP) and oxytocin (OT) con tent as well as changes in aggressiveness were measured in rats one we ek and one month after the surgical intervention. The main results are as follows: (1) the compression of the pituitary stalk elicits a chro nic increase in water consumption, as well as in CSF vasopressin and o xytocin content; (2) the surgical intervention increased the frequency of clinch fighting after one week. The increase in aggressiveness acc entuated after one month and, in addition, operated animals showed red uced scores of resting while exploratory and social behaviours increas ed; (3) there was a strong positive correlation between water consumpt ion, vasopressin, and aggressiveness; (4) oxytocin changes showed a po sitive correlation with variation in social behaviour, The surgical in tervention may serve as a model for lesions of the pituitary stalk and formation of ectopic neurohypophyses in humans.