Vasopressin in affective illness.

Animal studies have revealed two important aspects of vasopressin function which make this peptide a suitable candidate for involvement in complex behavioural syndromes: (1) vasopressin deficiency produces deficits of behaviour which are reversed by vasopressin; (2) well-developed systems exist for the distribution of vasopressin throughout the central nervous system (C.N.S.) via either peptidergic neurons or the cerebrospinal fluid (C.S.F.) and provide the means by which vasopressin may regulate cells controlling behavioural or physiological processes. Among the processes which vasopressin can influence are several of significance in the symptom-complex of affective illness, including alterations in memory, changes in pain sensitivity, synchronisation of biological rhythms, the timing and quality of R.E.M. sleep, and the regulation of fluid and electrolyte balance. In addition, vasopressin is functionally linked to monoamine neurotransmitter systems and, like them, is altered by pharmacological agents which affect mood. Some of the pharmacological and clinical data suggest that vasopressin function is diminished in depression and augmented in mania; sometimes, however, alterations in vasopressin function may be detectable only during crucial periods of the manic-depressive cycle. The hypothesis that vasopressin plays a role in disorders of human behaviour, particularly manic-depressive illness, can now be directly tested by radioimmunoassays of vasopressin in C.S.F. and plasma and by the administration of specific vasopressin analogues and inhibitors.