Hyperlocomotion induced by inhalation of nicotine and a low dose of Δ9‐Tetrahydrocannabinol in female rats

Abstract

BackgroundsGrowing availability of e‐cigarette devices permits users to prepare their own cocktail of drugs for inhalation, including polysubstance inhalation. Some individuals use nicotine and (−)‐Δ9‐tetrahydrocannabinol (THC) in combination by smoking tobacco and cannabis together or in sequence; this practice may extend to electronic cigarette users. THC exerts biphasic effects on locomotion in rats, with high doses (e.g., 5 mg kg−1, i.p.) decreasing, and lower doses (e.g., 0.03 mg kg−1, i.p.) increasing, locomotor activity. Nicotine (NIC) also increases locomotor activity in rodents. This study was designed to determine if interactive effects of THC and NIC result from vapor inhalation in rats using a novel e‐cigarette based procedure.MethodsFemale Sprague‐Dawley rats were exposed to vapor produced by the propylene glycol vehicle (PG), NIC (1 mg/mL in PG), THC (12.5 mg/ml in PG) or a combination of NIC with THC for a duration of 15 minutes. Body temperature and locomotor responses were evaluated post‐inhalation using a radiotelemetry system.ResultsLocomotor activity was increased in the rats for the first 60 min after NIC (1 mg/ml) exposure and this effect was blocked by pretreatment with mecamylamine. Activity was also increased 15 min after initiation of THC vapor compared with PG. Female rats did not show any further hyperlocomotion following exposure to the combination of NIC+THC vapor compared with either NIC or THC vapor inhalation, alone. The body temperature was decreased following the THC (12.5 mg/ml) or a combination of THC (12.5 mg/ml) +NIC (1 mg/ml) inhalation with significant effects starting 120 min post‐exposure, while NIC (1 mg/ml) inhalation did not alter the body temperature.DiscussionVapor inhalation of NIC or low dose THC stimulates locomotor activity in female rats. The co‐administration of a lower dose of THC with NIC produced no additive locomotor stimulation in female rats compared to either THC or NIC alone. The observed data provided behavioral evidence to suggest that the effect of nicotine on locomotion might not be modified by the physiological action of cannabinoids.Support or Funding InformationFunding support provided by USPHS grants AA007456, DA035482 and DA041967This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.