The effects of clonidine and yohimbine in the tail flick and hot plate tests in the naked mole rat (Heterocephalus glaber)

Abstract

Objective: The naked mole rat (NMR) (Heterocephalus glaber) is increasingly considered an important biomedical research model for various conditions like hypoxic brain injury, cancer and nociception. This study was designed to investigate the effects of clonidine and yohimbine, an alpha-2 (α2) adrenoceptor agonist and antagonist respectively in the tail flick and hot plate tests. Results: A significant difference in tail flick latency was noted between saline control and 30µg/kg clonidine, which was reduced after administration of 30µg/kg yohimbine. A significant difference in hot plate latency was also noted between saline control and 30µg/kg clodinine during the periods 30, 45, 60, 75 and 90 minutes after administration, and between saline control and 10µg/kg clonidine during 30 minutes after administration. The hot plate latency by 30µg/kg clonidine was also reduced by 30µg/kg yohimbine during 30 minutes after administration. Since the tail-flick and hot plate tests mediate the effects at spinal and supraspinal levels respectively, the present study indicates the presence and involvement of noradrenergic receptors in thermal antinociception at spinal and supraspinal levels of the NMR, similar to what has been found in other mammals.