The behavior of worker and non-worker rats under the influence of (-) 9 -trans-tetrahydrocannabinol, chlorpromazine and amylobarbitone

Reversible effects of acute and long-term administration of delta-9-tetrahydrocannabinol (THC) on memory in the rat

A study was designed to develop a measure of both acute and chronic effects of THC administration on memory in the rat. Errors in an 8-arm radial maze, before and after two delay intervals (5 s and 1 h, introduced between the fourth and the fifth arm choice), constituted the principal dependent measures. The first experiment involved testing the animals shortly after administration of 1.25 mg/kg THC. The drug did not affect performance in the pre-delay tests, although a significant effect was observed after the 5-s delay but not after 1-h delay. In the second experiment, 5 mg/kg THC or saline were administered 6 days/week for 90 days. Testing was conducted 18 h after each drug administration. During chronic administration the pre-delay performance did not differ between groups but the post-delay performance of the THC group deteriorated in a gradual manner, relative to their controls, in both the 5-s and 1-h delay conditions. After discontinuation of drug administration, the differences between groups reversed only after 30 days. The results provided evidence that both acute and chronic administration of THC affected working-memory in the radial arm maze test, although it did not interfere with the general cues of the task (reference memory). Chronic drug effects on memory were reversible after prolonged abstinence. Thus, the 8-arm radial maze task proved to be a useful measure of THC effects on memory and could be further used to investigate more thoroughly the mechanisms involved in such drug effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Behavioral effects of hashish in mice. IV. Social dominance, food dominance, and sexual behavior within a group of males

Within groups of three adult male mice the acute and subchronic effects of hashish extract (20 mg delta 9-THC/kg) on social dominance, food dominance, and sexual interactions with a female were investigated. An initial drug treatment of only the dominant male weakened his social position, but dominance was regained after treatment 2 or 3. In contrast, a persistent change in dominance was found when only the male which was dominant in the feeding test was treated with the extract. Simultaneous drug treatment of all three males did not affect the social dominance relationship but resulted in a reversible change in food dominance. The original feeding order was reestablished after drug treatment 3. Upon meeting an estrous female, no male of the group was distinctly dominant in mating. After treatment 1 was given to all members of the group, all types of behavior were impaired and total activity was significantly reduced. After treatment 2, animals showed tolerance to the sedative effects, and after treatment 3, sexual behavior was even more frequent in drugged animals than in controls. The results are discussed in relation to a possible dependence of behavioral drug effects and tolerance development on the experimental situation.

Correlation between Individual Differences in Rats' Performance and the Outcome of Social Worker-Parasite Relationship

An experiment was designed to predict the outcome of establishing a worker-parasite relationship between rats paired in a modified Skinner box with the water dipper and the bar attached to opposite walls. The rats were first trained individually to press the bar for water reward. After this individual training the reinforcement, besides being contingent to the pressing response, began also to be freely delivered (by the experimenter) in a variable-interval schedule of reinforcement. The number of such sessions each animal took to stop emitting the bar-pressing response was recorded. After stopping the operant response the animals were again trained individually. Following that they were paired in the experimental cage according to the number of sessions they took to stop the bar-press response. After the development of the worker-parasite relationship, categorization into workers and parasites could be predicted according to the number of sessions the rats took to stop the response in the individual condition. Individual characteristics may then play a role, among a multitude of other possible variables, in the outcome of the worker-parasite relationship between rats.

Cannabis intoxication: effects of monetary incentive on performance, a controlled investigation of behavioural tolerance in moderate users of cannabis

The study examined the effect of monetary incentive on the performance of five tasks after two heterogeneous groups of experienced users of cannabis and previously naive subjects had smoked placebo material and two dose levels of cannabis. The performance of the motivated subjects was compared with that of two non-motivated matched groups. Dose-related impairment was found on four of the five tasks, supporting previous findings of cannabis-induced impairment of short-term memory, goal-directed behavior and choice reaction times. Results for three of the tasks suggested that the performance of the motivated subjects was less affected by the drug than was the performance of the non-motivated subjects. There was no difference between the performance of subjects naive and experienced with respect to drug use.