Increased Drinking following Social Isolation Rearing: Implications for Polydipsia Associated with Schizophrenia

PLOS ONE, February 2013

23441161

Emily R. Hawken, Nicholas J. Delva, Richard J. Beninger

Primary polydipsia, excessive drinking without known medical cause, is especially associated with a diagnosis of schizophrenia. We used animal models of schizophrenia-like symptoms to examine the effects on schedule-induced polydipsia: post-weaning social isolation rearing, subchronic MK-801 treatment (an NMDA-receptor antagonist) or the two combined. Male, Sprague-Dawley rats reared in groups or in isolation beginning at postnatal day 21 were further divided to receive subchronic MK-801 (0.5 mg/kg twice daily) or saline for 7 days beginning on postnatal day 62. Following a 4-day withdrawal period, all groups were trained on a schedule-induced polydipsia paradigm. Under food-restriction, animals reared in isolation and receiving food pellets at 1-min intervals developed significantly more drinking behavior than those reared with others. The addition of subchronic MK-801 treatment did not significantly augment the amount of water consumed. These findings suggest a predisposition to polydipsia is a schizophrenia-like behavioral effect of post-weaning social isolation.