M. Marlyne Kilbey

?9-tetrahydrocannabinol induced inhibition of predatory aggression in the rat

AbstractΔ9-tetrahydrocannabinol inhibits predatory aggression in rats. Increases in the degree of inhibition are obtained with increasing dosages of the drug. Although sex and strain of the subjects varied nonsystematically, inhibition of predatory aggression uniformly was found to be dose related. Readministration of Δ9-tetrahydrocannabinol did not effect motor activity measures at dose levels which inhibit aggression. Administration of Δ9-tetrahydrocannabinol increases whole brain serotonin, while norepinepherine is largely unaffected, indicating that the anti-aggressive effect may be mediated, in part, by serotonergic mechanisms.

Δ-9-Tetrahydrocannabinol: Inhibition of deprivation- and carbachol-induced water consumption in the rat after central and peripheral administration

Male rats were used in three experiments to assess the effects of Δ-9-tetrahydrocannabinol on drinking behavior. In study 1, water consumption during a 1-hr drinking period was stabilized, and then each S received one of six levels of Δ-9-tetrahydrocannabinol. A dose-dependent depression of drinking was found. In study 2, 15 male rats increased water consumption when carbachol was administered via indwelling lateral hypothalamic cannulae. The effect was blocked by administration of Δ-9-tetrahydrocannabinol. In experiment 3, Δ-9-tetrahydrocannabinol was applied to the brain of six rats, via hypothalamic cannulae, and a depression of drinking was found. These data suggest an anticholinergic action of Δ-9-tetrahydrocannabinol although the possibility that the effects may result from a norepinephrine mechanism should not be overlooked.

Behavioral, biochemical and maturation effects of early DL-para-chlorophenylalanine treatment

DL-para-Chlorophenylalanine was administered to albino rats daily from within eight hours of birth for various lengths of time during the 30 day postnatal cortical development period. In experiment one, whole brain serotonin and plasma phenylalanine were measured 24 and 72 h post treatment in 7, 14, 21, and 28 day rats. The data are interpreted as supporting the hypothesis that DL-para-chlorophenylalanine may be used to institute the biochemical characteristics of phenylketonuria. The DL-para-chlorophenylalanine-treated Ss weighed significantly less at 14 days of age and thereafter and, also, were less strong. One hundred mg/kg DL-para-chlorophenylalanine was administered daily from birth through day 30 for experimental Ss of studies two and three. In experiment two maturation indices were reported to be retarded in drug-treated Ss for behaviors involving the skeletal-muscular system and activity measures were reported to be lower at 25, 45, and 121 days of age. Experiment three showed that acquisition of a conditioned pole climb avoidance and/or escape response measured at 180 days of age was poor in early drug-treated Ss. These data were interpreted as indicating that early DL-para-chlorophenylalanine-treated Ss show some degree of behavioral deficit at maturity.

Effects of dl-para-chlorophenylalanine on sucrose preference and intake: Reversal by 5-hydroxytryptophan and 6-methoxy 1,2,3,4,-tetrahydro-β-carboline

Abstract In two experiments involving 12- or 4-hr two-bottle preference tests, rats depleted of brain serotonin by dl -para-chlorophenylalanine (pCPA) injections consumed larger amounts of sucrose and had a higher preference for sucrose solutions over distilled water than vehicle-injected control animals. Injection of 5-hydroxytryptophan (5-HTP) or 6-methoxy-1,2,3,4-tetrahydro-β-carboline (6-MeO-THBC) was found to reverse the effects of pCPA on brain serotonin as well as reverse the increased sucrose preference produced by pCPA.

Self-selection of 5-hydroxytryptophan in dl-para-chlorophenylalanine treated rats ☆

Abstract Male Sprague-Dawley rats were depleted of serotonin (5-HT) by i.p. injections of dl-para-chlorophenylalanine (p-CPA). In a 36-hr two-bottle preference test, animals were allowed to choose between distilled water (H 2 O) and a solution of free base 5-hydroxytryptophan (5-HTP), a precursor of 5-HT. The p-CPA-treated animals showed significantly greater preference for the 5-HTP solution than the control animals. A significant increase in brain levels of 5-HT was found for the 5-HT-deficient group following consumption of 5-HTP.

Time course of Δ9-tetrahydrocannabinol inhibition of predatory aggression

Abstract Three studies assessed the time course of inhibition of predatory aggression and changes in levels of brain serotonin following administration of Δ 9 -THC. In Study One, six groups of six rats each were administered 1.25 mg/kg Δ 9 -THC IV and frog-killing behavior was measured at six postinjection intervals: 30, 60, 90, 150, 210, and 270 minutes. In Study Two, four groups of six rats each were tested. Group One received a vehicle control injection and was tested immediately, i.e. zero-minutes, postinjection. The remaining groups received 1.25 mg/kg Δ 9 -THC, and behavior was measured at 0, 15, and 30 min postinjection. In Study Three, two groups of six rats were treated with the vehicle or 1.25 mg/kg Δ 9 -THC and sacrificed one minute postinjection. Additional drug groups were sacrificed at 30 and 210 min postinjection. Levels of 5-HT were determined in four brain sections: cortex, midbrain, medulla, and cerebellum. Significant inhibition of predatory aggression was found for groups tested at 0, 15, and 30 min postinjection. Brain levels of 5-HT in the midbrain and/or medulla were significantly increased over the same period.

Effects of Δ-9-tetrahydrocannabinol on appetitive- and aggressive-rewarded maze performance in the rat

Forty-two rats were trained in a T-maze with the opportunity to obtain food (21 rats) or attack a frog (21 rats) as a reward for choosing the side designated correct Following training, three dosage levels of Δ-9-tetrahydrocannabinol were administered. Differential effects of drug administration on behavior were found to be a function of the type of reward employed, indicating that Δ-9-tetrahydrocannabinol had a more profound inhibitory effect on aggression than on appetite.