Litter has an effect on the behavioural changes caused by the administration of the nitric oxide synthase inhibitor NG-nitro-L-arginine and ethanol in mice

The aim of the work was to study the effects of litter and the nitric oxide synthase (NOS) inhibitor NG-nitro-L-arginine (L-NOARG) on the behaviour of mice after acute and chronic ethanol administration and withdrawal. Male outbred NIH/S mice, from 21 litters, were distributed among experimental groups and subjected to acute and chronic ethanol administration. After acute or chronic ethanol administration, the effects of L-NOARG on the behaviour of mice in the plus-maze test were studied. Acute ethanol (1 g/kg, i.p.), L-NOARG (20 and 40 mg/kg, i.p.) and their combination induced an anxiolytic effect. Furthermore, the values for the representatives of different litters tended to be either above or below the group mean, irrespective of the drug treatment. Chronic ethanol administration (23 days by inhalation) induced an anxiolytic effect and ethanol withdrawal induced an anxiogenic effect in the plus-maze. The administration of L-NOARG (20 mg/kg, i.p.) induced an anxiolytic effect in control mice and had no effect on ethanol-intoxicated mice, but attenuated the anxiogenic effect of ethanol withdrawal in the plus-maze. However, after chronic ethanol administration and withdrawal, litter had no effect on the behaviour of mice. If the litter is a significant determinant in the behaviour of outbred mice, then the use of information about the litter origin of animals could serve for the purposes of reduction. But only if this information is available from breeders.