The effects of compounds related to gamma-aminobutyrate and benzodiazepine receptors on behavioural responses to anxiogenic stimuli in the XXXX : extinction and successive discrimination.

@entity6341 @entity1027 @entity969 @entity8685 @entity5094 @entity11170 @entity35 @entity1772 @entity734
In a first set of experiments @entity35 were trained to run in a straight alley for food reward on a continuous reinforcement schedule and the running response was then extinguished. On the last 2 days of training and daily throughout extinction different groups of animals were injected IP with saline, 5 mg/kg @entity8685 , 0.75 mg/kg @entity5094 , @entity8685 + @entity5094 , @entity8685 + 1.5 mg/kg @entity1027 , 0.00125 or 0.25 mg/kg @entity6341 , 1 mg/kg @entity1772 , @entity8685 + @entity1772 , or 0.00125 mg/kg @entity6341 + @entity1772 . @entity8685 increased resistance to extinction, a well-known anxiolytic effect. This effect was blocked by both @entity5094 and @entity1027 . @entity5094 on its own reduced resistance to extinction (an anxiogenic-like effect). Whether given alone or in combination with other drugs, @entity6341 and @entity1772 had no effect. In a second set of experiments @entity35 were trained in a successive operant discrimination (signalled by a @entity11170 or steady light) between components in which @entity969 reward was available on a variable-interval schedule for barpressing and components in which no reward was given. @entity8685 at 10 mg/kg increased responding in both rewarded and nonrewarded components, but more in the latter than could be accounted for by change in the former. This effect is as expected with an anxiolytic drug. It was not altered by administration of @entity1027 at 1.5 or 1.75 mg/kg; at 2 mg/kg @entity1027 acted synergistically with @entity8685 . @entity5094 (1 and 1.5 mg/kg) also acted synergistically with @entity8685 , enhancing the latter's rate-increasing effects, but only during rewarded components. Neither @entity6341 (0.00125 and 0.25 mg/kg) nor @entity1772 (0.01 mg/kg) affected response rates, whether given alone or in combination. However, @entity1772 in a dose of 1 mg/kg, provided it was given to @entity35 also injected with @entity6341 (0.00125 or 0.25 mg/kg) at other times, significantly reduced responding during nonrewarded components (an apparently anxiogenic effect). The results of the two sets of experiments are discussed in relation to the hypothesis that @entity734 affect behaviour by increasing GABAergic inhibition.
