Increased basal plasma vasopressin-neurophysin in mania

Basal plasma vasopressin-neurophysin (hNpI) was estimated in 50 drug-free neuropsychiatric patients classified according to the Research Diagnostic Criteria. The hNpI concentration was higher in the 5 manics (0.76 +/- 0.15 ng/ml) than in the 16 schizophrenics (0.53 +/- 0.08), 12 minor depressed (0.54 +/- 0.06) and 17 major depressed (0.48 +/- 0.10; p less than 0.05). Thus, those results confirm our initial observation of an increased vasopressinergic function in the manic compared to the depressed phase in one bipolar patient. Whether this increase in the vasopressin release is a consequence of the neuropsychiatric disorders or initiates and/or participates in their pathophysiology remains to be elucidated. The hypothetic consequence on water metabolism of such an increase remains also to be defined.