Locomotor Activity in Photocell Cages
Objective: Measurement of locomotor activity in photocell cages following nicotine or saline injection over an 80-minute period to assess the effects of nicotine on locomotor activity in non-tolerant and tolerant rats
Protocol Steps
Prepare test subject
Rats were prepared for testing in photocell cages
Note: Subjects included both non-tolerant and tolerant rats
View evidence from paper
“Rats were tested for locomotor activity in photocell cages”
Administer injection
Subcutaneous injection of either (-)-nicotine bitartrate or 0.9% w/v NaCl solution (saline) immediately before testing
Note: Injection administered immediately before the start of the 80-minute testing period
View evidence from paper
“for 80 min starting immediately after subcutaneous injection of (-)-nicotine bitartrate or 0.9% w/v NaCl solution (saline)”
Measure locomotor activity
Record locomotor activity in photocell cages for 80 minutes following injection
Note: Activity measurements begin immediately after injection
View evidence from paper
“Rats were tested for locomotor activity in photocell cages, for 80 min starting immediately after subcutaneous injection”
Observe behavioral effects in non-tolerant subjects
Monitor for depressant action and ataxia in the first 20 minutes, followed by increased activity later in the session
Note: Effects are dose-dependent with nicotine doses of 0.1 to 0.4 mg/kg base
View evidence from paper
“nicotine (0.1 to 0.4 mg/kg base) depressed activity and induced ataxia in the first 20 min, but increased activity later in the session; these actions were dose-dependent”
Conduct tolerance studies
Compare rats given daily or weekly nicotine (0.4 mg/kg s.c.) with control rats given saline. Test each subject once weekly with nicotine and once with saline
Note: Tolerance to the depressant action of nicotine persisted for at least 3 weeks
View evidence from paper
“Tolerance was studied by comparing rats given nicotine (0.4 mg/kg s.c.) every day with control rats given saline instead. Each week, every subject was tested once with nicotine (0.4 mg/kg) and once with saline”
Test mecamylamine effects in non-tolerant subjects
Administer mecamylamine (0.5, 1.0 mg/kg s.c.) prior to nicotine (0.4 mg/kg) to assess prevention of initial depressant action
Note: Mecamylamine prevented the initial depressant action of nicotine in non-tolerant subjects
View evidence from paper
“In non-tolerant subjects, mecamylamine (0.5, 1.0 mg/kg s.c.) prevented the initial depressant action of nicotine (0.4 mg/kg)”
Test mecamylamine effects in tolerant subjects
Administer mecamylamine (0.1, 0.32, 1.0 mg/kg s.c.) prior to nicotine (0.4 mg/kg) to assess prevention of locomotor stimulant action in a dose-related manner
Note: Mecamylamine prevented the locomotor stimulant action of nicotine in tolerant rats in a dose-related way
View evidence from paper
“In tolerant rats, the locomotor stimulant action of nicotine (0.4 mg/kg) was prevented by mecamylamine (0.1, 0.32, 1.0 mg/kg s.c.) in a dose-related way”
Test hexamethonium effects in tolerant subjects
Administer hexamethonium (0.2, 1.0, 5.0 mg/kg s.c.) prior to nicotine (0.4 mg/kg) to assess effects on locomotor stimulant action
Note: Hexamethonium had little or no effect on the locomotor stimulant action of nicotine in tolerant rats
View evidence from paper
“the quaternary ganglion blocker, hexamethonium (0.2, 1.0, 5.0 mg/kg s.c.) had little or no such effect”
Test antagonist alone
Administer mecamylamine or hexamethonium alone without nicotine to assess baseline effects
Note: Neither mecamylamine nor hexamethonium altered activity when given alone
View evidence from paper
“Neither mecamylamine nor hexamethonium altered activity when given alone”