Effects of cannabis drugs on social behaviour of laboratory rodents

Khat (Catha edulis F.) and cannabinoids: Parallel and contrasting behavioral effects in preclinical and clinical studies

After a brief outline of Catha edulis F. (khat) and the cannabinoid systems, the interactions between the pharmacological effects of khat and cannabinoids will be reviewed. Khat chewing is a widespread habit that has a deep-rooted sociocultural tradition in Africa and the Middle East. Experimental studies conducted to investigate khat's central and peripheral effects have revealed an amphetamine-like mechanism of action mediated through the dopaminergic system. The endocannabinoid system comprises the receptors, the endogenous agonists and the related biochemical machinery responsible for synthesizing these substances and terminating their actions. Endocannabinoids are synthesized "on demand" from membrane phospholipids and then rapidly cleared by cellular uptake and enzymatic degradation. Khat and cannabinoids produce a body of parallel and contrasting behavioral effects. Concurrent consumption of khat and cannabinoids may increase the risk of getting or precipitating psychosis, has rewarding and motivational effect, increases the threshold of pain perception and impairs learning and memory. On the other hand, the action of cannabis to enhance food intake is likely to reduce khat's appetite suppressant effects.

Hu 210: a potent tool for investigations of the cannabinoid system

The synthetic compound HU 210 displays a multiplicity of biochemical, pharmacological, and behavioral effects, most of which have been demonstrated to be dependent on a selective agonistic activity at CB(1) and CB(2) cannabinoid receptors and to involve the main neurotransmitter systems. Results obtained in various studies suggest a potential clinical application of this highly potent drug (e.g., as antipyretic, antiinflammatory, analgesic, antiemetic, and antipsychotic agent) as well as its usefulness in research aimed to develop a better understanding of the involvement of the endogenous cannabinoid system in a number of physiopathological functions.

Inhibitory effects of the cannabinoid agonist HU 210 on rat sexual behaviour

The present study investigates the effects induced by the cannabinoid agonist HU 210 (25-100 microg/kg, administered intraperitoneally [i.p.]) on the following parameters: (a) sexual behaviour of male rats, categorised on the basis of seven consecutive mating pretests as sexually active (SA) and sexually inactive (SI) and (b) sexual receptivity of ovariectomised female rats displaying hormonally induced heat. The data obtained show that HU 210, administered in acute or subchronic mode (once daily for 7 and 14 days), impaired the copulatory pattern of SA rats in a dose- and mode-dependent manner, decreasing their sexual drive, mainly as represented by an increase in mount and intromission latencies, and affecting ejaculation mechanisms (represented as a decrease in intromission frequency and increase in ejaculation latency). After subchronic treatment with the highest dose had been suspended for 2 weeks, SA males' performance was still impaired. In SI rats, acute injections of the drug (25 and 50 microg/kg, i.p.) at the higher dose increased contact latency and decreased genital exploration time towards the female. Acute HU 210 (25-100 microg/kg, i.p.) also inhibited female sexual behaviour, potently reducing lordosis quotient and lordosis intensity.