[A change in the alarm level entails a change in behavioural strategy of mice in stress and a change in analgesia induced by it].

The effects of anxiogenic (pentylentetrazole) and anxiolytic (diazepam) agents on <> and cold swim stress-induced analgesia were investigated in SHR and NMRI male mice. It was shown that behavioral response to acute stress was associated with a change in the pain tolerance threshold. Diazepam increased immobility time and attenuated stress-induced analgesia (SIA). NMRI mice were more responsive to anxiolytic than the SHR mice, but the lattes manifested more dramatic changes when anxiety was pharmacologically enhanced (immobility time was significantly reduced and the SIA exaggerated). Our findings suggest that the main parameters change in reciprocal manner following a pharmacologically altered anxiety, and reveal that differences between two strains of mice are determined by differences in their sensitivity to stress.