Atrial natriuretic peptide and arginine vasopressin secretion in schizophrenic patients

Abstract

Plasma levels of arginine vasopressin (AVP) and atrial natriuretic peptide (ANP) were measured in 15 patients with schizophrenic or schizoaffective disorders and 15 healthy volunteers during oral water loading at 20 ml/kg. In the patient group, plasma AVP was secreted even when plasma osmolality was below 270 mosmol/kg, although the sensitivity of AVP secretion response to osmolality was lower than in the controls. The ANP level was higher in the group of patients than in the controls. There was a negative correlation between plasma ANP and osmolality in the patients. We speculate that the volume expansion caused by inappropriate AVP secretion stimulated plasma ANP release and that the natriuresis resulting from the elevated plasma ANP level might contribute to hyponatremia.

Absence of a Difference in the Neurosecretory Activity of Supraoptic Nucleus Vasopressin Neurons of Neuroleptic-Treated Schizophrenic Patients

“…The present study shows that in spite of the many articles indicating abnormalities in the regulation of VP secretion in schizophrenia [1,2,3,4,5,6,7,8], no differences were found in a number of activity measures for VP neurons of the dl-SON between schizophrenics and controls. Our sample consisted of schizophrenics under neuroleptic treatment with no documented evidence of polydipsia in their clinical reports.…”

“…Dysfunction in water intake and metabolism has frequently been reported in schizophrenia [1,2,3,4,5,6,7,8,9,10,11]. Recent epidemiological studies indicate that primary polydipsia is still an enduring problem for about 20% of the chronic inpatients [9].…”

“…Under water load, drug-free psychotic patients had a significantly lower cumulative urine output and higher minimum urine osmolalities as compared with healthy volunteers, indicating that water intoxication may develop during acute exacerbations of psychoses due to impaired excretory mechanisms [4,5]. Schizophrenics on neuroleptic medication have lower plasma levels of VP at comparable values of plasma osmolality than healthy volunteers and show gentler slope of the regression line and lower threshold of VP secretion [3, 6, 8]. Water load tests indicated that, while in healthy volunteers plasma VP is not secreted below a lower limit of plasma osmolality of 270 mosm/kg, in schizophrenics under medication VP is secreted even when the plasma osmolality falls below this limit [6, 8].…”

“…Schizophrenics on neuroleptic medication have lower plasma levels of VP at comparable values of plasma osmolality than healthy volunteers and show gentler slope of the regression line and lower threshold of VP secretion [3, 6, 8]. Water load tests indicated that, while in healthy volunteers plasma VP is not secreted below a lower limit of plasma osmolality of 270 mosm/kg, in schizophrenics under medication VP is secreted even when the plasma osmolality falls below this limit [6, 8]. Failure of VP secretion and induction of diabetes insipidus is reported to coexist with polydipsia in schizophrenic patients after chronic treatment with neuroleptic drugs [12, 13].…”

Differential sensitivity of the Brattleboro rat to glutamatergic and dopaminergic perturbation

“…VP is also involved in behavioral outcomes important in the etiology of schizophrenia such as learning and memory, aggression, and sociality [23]. In addition, both glutamate and VP antagonism have been associated with negative symptoms of schizophrenia, suggesting a potential interaction between glutamate and VP signaling in the brain [24][25][26]. Moreover, there is evidence that VP activity in the hypothalamus may be regulated by glutamatergic signaling [22].…”