Acute and chronic effects of the triazolobenzo-diazepine, alprazolam, on defeat and analgesia evoked by conspecific attack in male mice.
Behavioural and pharmacological evidence suggest that non-opioid analgesia in defeated male mice is a consequence of anxiety provoked by ecologically relevant aspects of the stimulus situation. The effects of acute and chronic alprazolam (0.05-2.0mg/kg, i.p.) treatment on basal nociception, defeat behaviour and analgesia evoked by conspecific attack are assessed. Results show that basal nociception (tail-flick assay) was unaffected by acute or chronic drug treatment, and that attack-induced analgesia was unaltered by acute administration of 0.05-0.50mg/kg alprazolam. Higher acute doses (1-2mg/kg) of the compound inhibited locomotor activity, markedly interfered with the display of defeat postures and resulted in the exposure of intruders to higher than normal levels of attack. Though 1mg/kg alprazolam (acute) significantly inhibited the analgesic consequences of conspecific attack, this effect went at a higher dose. Chronic drug administration led to the development of tolerance to the inhibitory effects of higher alprazolam doses on locomotor activity and, over the dose range 0.5-2mg/kg, to the complete inhibition of analgesic consequences of conspecific attack. Nonetheless, mice treated chronically with 0.5-2mg/kg still failed to display defeat within the maximum time allotted for encounters, suggesting that this behavioural effect may be a valid index of anxiolytic activity. Data are discussed in relation to the possible involvement of panic in intruder analgesia.
Shepherd
J.K.
JK
Pharmacoethology Laboratory, Department of Psychology, University of Bradford, UK Correspondence: Department of Psychology, University of Leeds, Leeds LS2 9JT, UK.
Rodgers
R.J.
RJ