Nicotine chronic tolerance development and withdrawal in the planaria (Schmidtea mediterranea)

Chronic nicotine exposure reduces sensitivity to the effects of nicotine, which then results in behavioural changes and tolerance development. In planaria, a valuable first-stage preclinical model for addictive behaviour, acute administration has been shown steadily alter motility animals, result that interpreted as evidence withdrawal effects; however, chronic - typically regarded condition development role contextual cues have not systematically assessed. The present study assessed on planarians (Schmidtea mediterranea). animals experimental groups received long (ten daily 30 min exposures); control group was exposed water same context but absence drug. closely monitored every exposure. Following this phase, all were subject three different tests: presence (without drug, Test 1); (Test 2); drug novel 3). Exposure consistently reduced motility; increased with repeated exposures an instance Tolerance dependent nicotinic receptor activation, because it blocked by co-administration mecamylamine. However, found be independent where had experienced. are discussed reference existent theories drugs.