Effects of tetrahydrocannabinol on hippocampal evoked afterdischarges in cats

Marijuana intoxication in a cat

Background

Cannabis from hemp (Cannabis sativa and C. indica) is one of the most common illegal drugs used by drug abusers. Indian cannabis contains around 70 alkaloids, and delta-9-tetrahydrocannabinol (delta-9-THC) is the most psychoactive substance. Animal intoxications occur rarely and are mostly accidental. According to the US Animal Poison Control Center, cannabis intoxication mostly affects dogs (96%). The most common cause of such intoxication is unintentional ingestion of a cannabis product, but it may also occur after the exposure to marijuana smoke.

Case presentation

A 6-year-old Persian cat was brought to the veterinary clinic due to strong psychomotor agitation turning into aggression. During hospitalisation for 14 days, the cat behaved normally and had no further attacks of unwanted behaviour. It was returned to its home but shortly after it developed neurological signs again and was re-hospitalised. On presentation, the patient showed no neurological abnormalities except for symmetric mydriasis and scleral congestion. During the examination, the behaviour of the cat changed dramatically. It developed alternate states of agitation and apathy, each lasting several minutes. On interview it turned out that the cat had been exposed to marijuana smoke. Blood toxicology tests by gas chromatography tandem mass spectrometry revealed the presence of delta-9-tetrahydrocannabinol (THC) at 5.5 ng/mL, 11-hydroxy-delta-9-THC at 1.2 ng/mL, and 11-carboxy-delta-9-THC at 13.8 ng/mL. The cat was given an isotonic solution of NaCl 2.5 and 2.5% glucose at a dose of 40 mL/kg/day parenterally and was hospitalised. After complete recovery, the cat was returned to it’s owner and future isolation of the animal from marijuana smoke was advised.

Conclusions

This is the first case of a delta-9-tetrahydrocannabinol intoxication in a cat with both description of the clinical findings and the blood concentration of delta-9-THC and its main metabolites.

Synthetic cannabinoid WIN 55,212-2 mesylate enhances the protective action of four classical antiepileptic drugs against maximal electroshock-induced seizures in mice

The aim of this study was to determine the effect of WIN 55,212-2 mesylate (WIN--a non-selective cannabinoid CB1 and CB2 receptor agonist) on the protective action of four classical antiepileptic drugs (carbamazepine, phenytoin, phenobarbital, and valproate) in the mouse maximal electroshock seizure (MES) model. The results indicate that WIN (10 mg/kg, i.p.) significantly enhanced the anticonvulsant action of carbamazepine, phenytoin, phenobarbital and valproate in the MES test in mice. WIN (5 mg/kg) potentiated the anticonvulsant action of carbamazepine and valproate, but not that of phenytoin or phenobarbital in the MES test in mice. However, WIN administered alone and in combination with carbamazepine, phenytoin, phenobarbital and valproate significantly reduced muscular strength in mice in the grip-strength test. In the passive avoidance task, WIN in combination with phenobarbital, phenytoin and valproate significantly impaired long-term memory in mice. In the chimney test, only the combinations of WIN with phenobarbital and valproate significantly impaired motor coordination in mice. In conclusion, WIN enhanced the anticonvulsant action of carbamazepine, phenytoin, phenobarbital and valproate in the MES test. However, the utmost caution is advised when combining WIN with classical antiepileptic drugs due to impairment of motor coordination and long-term memory and/or reduction of skeletal muscular strength that might appear during combined treatment.

The influence of cannabidiol and delta 9-tetrahydrocannabinol on cobalt epilepsy in rats

The mechanisms of the anticonvulsant activity of cannabidiol (CBD) and the central excitation of delta 9-tetrahydrocannabinol (delta 9-THC) were investigated electrophysiologically with conscious, unrestrained cobalt epileptic rats. The well-known antiepileptics, trimethadione (TMO), ethosuximide (ESM), and phenytoin (PHT), were included as reference drugs. Direct measurements were made of spontaneously firing, epileptic potentials from a primary focus on the parietal cortex and convulsions were monitored visually. ESM and TMO decreased the frequency of focal potentials, but PHT and CBD exerted no such effect. Although CBD did not suppress the focal abnormality, it did abolish jaw and limb clonus; in contrast, delta 9-THC markedly increased the frequency of focal potentials, evoked generalized bursts of polyspikes, and produced frank convlusions. 11-OH-delta 9-THC, the major metabolite of delta 9-THC, displayed only one of the excitatory properties of the parent compound: production of bursts of polyspikes. In contrast to delta 9-THC and its 11-OH metabolite, CBD, even in very high doses, did not induce any excitatory effects or convulsions. The present study provides the first evidence that CBD exerts anticonvulsant activity against the motor manifestations of a focal epilepsy, and that the mechanism of the effect may involve a depression of seizure generation or spread in the CNS.