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C Ksir

Publications and source records attributed to C Ksir.

6 recordsLinked to original sources
PubMed1991

Acute tolerance to the locomotor stimulant effects of nicotine in the rat.

Studies of peripheral nicotinic receptors have revealed that, after an initial agonist action, the receptors remain inhibited either through continued depolarization blockade due to continued presence of the agonist or through a brief inactivation of the receptor following its activation. If a similar phenomenon occurs at central nervous system nicotinic receptors, then behavioral responses to nicotine should exhibit an acute tolerance (tachyphylaxis). Groups of rats were given either saline or 0.2 mg/kg nicotine injections at 20-min intervals in photocell activity cages. A progressive decline in the locomotor responsiveness to nicotine was observed. The time course of this acute tolerance was observed in other rats given initial 0.2 mg/kg nicotine injections followed at differing time intervals by second 0.2 mg/kg nicotine test injections. The secondary antagonism to nicotine's locomotor stimulant effects was maximal at 45-60 min and recovered by 90-120 min. The locomotor response to 0.2 mg/kg nicotine test injections was observed in other rats following exposure to 1.8 mg/kg nicotine, and the behavioral response was attenuated for more than 5 h.

Animals↗
PubMed1978

Pentobarbital, promazine, d-amphetamine, and scopolamine effects on behavior under multiple and primed schedules of reinforcement.

Pigeons responded under compound fixed-interval (FI) fixed-ratio (FR) schedules of food presentation. Distinctive discrimininative stimuli were either continuously present during each component schedule (multiple FI FR) or were present only for a brief period at the beginning of each component (primed FI FR). Similar rates and patterns of responding were maintained under the multiple and primed schedules. Pentobarbital, scopolamine, and d-amphetamine decreased FR responding, but promazine had little effect at the doses studied. d-Amphetamine and promazine increased FI responding at certain doses, pentobarbital had little effect, and scopolamine decreased responding. There were no systematic differences in the effects of drugs under the multiple and primed schedules, in spite of the differences in discriminative stimuli under the conditions.

Animals↗
PubMed1977

LSD and d-amphetamine effects on fixed interval responding in the rat.

Food-deprived rats were trained to press a key which produced a food pellet for the first press after 3 min had elapsed (FI 3 min). Daily sessions consisted of 10 such intervals. Graded doses of LSD (0.04 - 1.28 mg/kg) and a d-amphetamine (0.5 - 2.0 mg/kg) were given 30 min before sessions. LSD produced a decrease in response rate at doses of 0.32 mg/kg and above, but did not disrupt the typical FI pattern of responding except at the highest dose (1.28 mg/kg). Amphetamine did not significantly alter the overall response rate, but caused a dose-related disruption of the FI response pattern, with previously low response rates increased more than higher rates, and occasional decreases in the previously highest rates. The experiment was repeated using the same rats responding on a multiple FIFR schedule. The presence of a 2000 Hz tone signalled FR periods; the tone was absent during FI periods. During the FR components, a pellet was produced after 30 responses had been emitted. The FI components were unchanged. LSD (0.08 - 0.32 mg/kg) again produced decreases in FI rate without altering the pattern, and amphetamine again altered the FI pattern without significantly changing overall rate.

Animals↗
PubMed1976

Rate dependent drug effects: possible state dependency.

Of 6 rats given extensive experience responding on a fixed-interval reinforcement schedule after injections of 1 mg/kg d-amphetamine, 3 showed significant rate dependent changes in responding when presession saline was substituted for d-amphetamine. Low rates were increased and high rates decreased by the change from d-amphetamine to saline, a result commonly found when d-amphetamine is first introduced. This indicates that rate dependent changes in fixed-interval responding may be state dependent phenomena.

Animals↗
PubMed1975

Scopolamine and amphetamine effects on discrimination: interaction with stimulus control.

A parametric examination of the interaction between drug-induced behavioral changes and the degree of predrug stimulus control was conducted with rats. A discretetrial simultaneous discrimination was used, with the controlling stimuli varied over 6 values of distinctiveness. The effects of graded doses of scopolamine, d-amphetamine, and methylscopolamine on these performances were studied, with both scopolamine and d-amphetamine showing no increase in error rate under strong stimulus control, and dose-related increases in error rate under weak stimulus control. The similar interaction between drug effect and stimulus control for scopolamine and d-amphetamine indicates that the interaction reflects the degree of susceptibility of the behaviors to drug action, rather than two specific drug-behavior interactions. Methylscopolamine produced a slight effect on error rate and no significant interaction with stimulus control. A decrease in the number of trials responded to was found with both scopolamine and methylscopolamine, but not with d-amphetamine.

Animals↗