Side effects of simultaneous alcohol and marijuana use

Cortical adrenoceptor expression, function and adaptation under conditions of cannabinoid receptor deletion

A neurochemical target at which cannabinoids interact to have global effects on behavior is brain noradrenergic circuitry. Acute and repeated administration of a cannabinoid receptor synthetic agonist is capable of increasing multiple indices of noradrenergic activity. This includes cannabinoid-induced 1) increases in norepinephrine (NE) release in the medial prefrontal cortex (mPFC); 2) desensitization of cortical α2-adrenoceptor-mediated effects; 3) activation of c-Fos in brainstem locus coeruleus (LC) noradrenergic neurons; and 4) increases in anxiety-like behaviors. In the present study, we sought to examine adaptations in adrenoceptor expression and function under conditions of cannabinoid receptor type 1 (CB1r) deletion using knockout (KO) mice and compare these to wild type (WT) controls. Electrophysiological analysis of α2-adrenoceptor-mediated responses in mPFC slices in WT mice showed a clonidine-induced α2-adrenoceptor-mediated increase in mPFC cell excitability coupled with an increase in input resistance. In contrast, CB1r KO mice showed an α2-adrenoceptor-mediated decrease in mPFC cell excitability. We then examined protein expression levels of α2- and β1-adrenoceptor subtypes in the mPFC as well as TH expression in the locus coeruleus (LC) of mice deficient in CB1r. Both α2- and β1-adrenoceptors exhibited a significant decrease in expression levels in CB1r KO mice when compared to WT in the mPFC, while a significant increase in TH was observed in the LC. To better define whether the same cortical neurons express α2A-adrenoceptor and CB1r in mPFC, we utilized high-resolution immunoelectron microscopy. We localized α2A-adrenoceptors in a knock-in mouse that expressed a hemoagglutinin (HA) tag downstream of the α2A-adrenoceptor promoter. Although the α2A-adrenoceptor was often identified pre-synaptically, we observed co-localization of CB1r with α2-adrenoceptors post-synaptically in the same mPFC neurons. Finally, using receptor binding, we confirmed prior results showing that α2A-adrenoceptor is unchanged in mPFC following acute or chronic exposure to the synthetic cannabinoid receptor agonist, WIN 55,212-2, but is increased, following chronic treatment followed by a period of abstinence. Taken together, these data provide convergent lines of evidence indicating cannabinoid regulation of the cortical adrenergic system.

The Relationship between Drug Use and Perceived Harmfulness

The present study was an extension of previous research on the perceived harmfulness of commonly used illicit and licit drugs. A large number of college students were asked to report on their experience with a number of drugs. These students were also asked to rate each drug on the degree to which they perceived that drug to be harmful or harmless. From their pattern of use, subjects were classified as being members of one of the following five groups: principled non-users, non-users, light users, moderate users and heavy users of marijuana. One-way analysis of variance was performed on the harmfulness ratings for each of the 12 drugs across groups. Results indicated that the groups differed significantly on their rating of the harmfulness of several drugs. Typically, these differences can be attributed to the contrast between the principled non-users of marijuana group and the other user groups. Cluster analysis was performed on the matrix of intercorrelations among the harmfulness ratings of the drugs by the combined non-users groups, the combined users groups and the total sample. The results of the cluster analysis indicated that for all subjects combined there were five major clusters, and for all non-users there were four major clusters as there were for all users. The drugs that comprise each cluster of drugs for each group and the mean harmfulness rating of the drugs within each cluster are reported. It was found that the users groups clustered LSD with cocaine, marijuana and hashish while the non-users clustered LSD with heroin. It was also found that within this sample, there were sex differences on the usage of marijuana, hashish, heroin, cocaine, alcohol, caffeine and aspirin. There were also sex differences on the harmfulness ratings of marijuana, hashish, cocaine, LSD and alcohol. The results of this study were compared with the results of previous research on the relationship between drug usage and the perceived harmfulness of drugs. Implications for future research are discussed.

Stroke after heavy marijuana smoking

I examined two young men who developed cerebral infarction associated with heavy marijuana smoking. Both were light tobacco smokers, but they did not drink alcohol or use other street drugs. Diagnostic work-up for nonatherosclerotic causes of stroke was unremarkable. I postulate that marijuana-associated alterations in systemic blood pressure resulted in vasospasm, leading to strokes in these patients.

A comparison of male users and nonusers of marijuana on the perceived harmfulness of drugs

Subjects (n = 108) who volunteered to participate in a study in which they expected to smoke marijuana were asked, as part of a screening procedure, to rate the harmfulness of a number of illicit drugs including marijuana. Subjects were separated into three groups according to their reported history of use of marijuana. The three groups were: naive users (at least 1 but no more than 25 incidences of use in a lifetime), light users (1 to 3 incidences of use per week), and heavy users (at least 5 incidences of use per week). Groups did not differ in terms of their perceived harmfulness of any of the drugs. Cluster analyses of the results for each group and for the total group indicated three distinct clusters: the drugs perceived to be the most harmful were heroin, morphine, and LSD; drugs perceived to be less harmful were cocaine, amphetamines, barbiturates, and nicotine; and the drugs perceived to be the least harmful were caffeine and marijuana, with marijuana being judged the least harmful of all the drugs.