The novel dehydroepiandrosterone (DHEA) derivative BNN27 counteracts behavioural deficits induced by the NMDA receptor antagonist ketamine in rats.

Consistent experimental evidence supports an important role of the glutamatergic system in the etiopathogenesis of schizophrenia. Numerous studies propose that blockade of the NMDA receptor by its antagonist ketamine impairs cognition and can mimic certain aspects of positive and negative symptoms of schizophrenia in rodents. Neuroactive steroids, including dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulphate (DHEAS) were shown to affect brain glutamatergic system and to be implicated in schizophrenia. BNN27 is a novel DHEA derivative, which is devoid of steroidogenic activity. The neuroprotective effects of BNN27 have been recently evidenced. The aim of the present study was to investigate the ability of BNN27 to counteract schizophrenia-like behavioural deficits produced by ketamine in rats. BNN27's ability to attenuate hypermotility, stereotypies and ataxia induced by ketamine were evaluated using a motor activity cage. To assess the efficacy of BNN27 to reverse non-spatial and spatial recognition memory deficits caused by ketamine, the object recognition task and the object location task were used. Finally, the social interaction test was utilized in order to examine the effects of BNN27 on ketamine-induced social withdrawal. BNN27 (3 and 6 mg/kg, i.p.) attenuated ketamine (10 mg/kg, i.p.)-induced ataxia and to some extent also hypermotility. BNN27 (3-6 mg/kg, i.p.) counteracted ketamine (3 mg/kg, i.p.)-induced non-spatial and spatial recognition memory deficits. Further, BNN27 (6 mg/kg, i.p.) reduced the ketamine (8 mg/kg, i.p.)-induced social isolation. Our findings show that BNN27 is sensitive to glutamate hypofunction produced by ketamine since it reduced schizophrenia-like behavioural deficits induced by this NMDA receptor antagonist in rats.