The antagonistic effects of naloxone on hypermotility in mice induced by dynorphin-(1-13) using a multi-dimensional...

The effects of intracerebral injection of dynorphin-(1-13) on spontaneous locomotor activity were investigated by using a newly devised multi-dimensional behavioural analyser based on a capacitance system. With this equipment, nine different measures of behavior exhibited by the mouse can be recorded. It was found that dynorphin-(1-13) (0.3 and 1 microgram) produced a significant increase in the linear locomotion recorded on the 1/1 and 1/2 counters. In addition, dynorphin-(1-13) (0.3 micrograms) significantly increased the grooming behavior recorded on the 1/16 counter. As the dynorphin-(1-13)-induced behavioural effects were reversed by pretreatment with relatively small doses of naloxone (0.5, 1 and 2 mg/kg), the dynorphin-induced increases in linear locomotion and grooming are probably mediated through opiate receptors in the brain.