Effect of subchronic treatment with (-) 8 -trans-tetrahydrocannabinol ( 8 -THC) on food intake, body temperature, hexobarbital sleeping time and hexobarbital elimination in rats

Effects of Cannabinoid Agonists and Antagonists on Sleep in Laboratory Animals

The cannabinoids are a family of chemical compounds that can be either synthesized or naturally derived. These compounds have been shown to modulate a wide variety of biological processes. In this chapter, the studies detailing the effects of cannabinoids on sleep in laboratory animals are reviewed. Both exogenous and endogenous cannabinoids generally appear to decrease wakefulness and alter rapid eye movement (REM) and non-REM sleep in animal models. In addition, cannabinoids potentiate the effects of sedative-hypnotic drugs. However, the individual contributions of each cannabinoid on sleep processes is more nuanced and may depend on the site of action in the central nervous system. Many studies investigating the mechanism of cannabinoid effects on sleep suggest that the effects of cannabinoids on sleep are mediated via cannabinoid receptors; however, some evidence suggests that some sleep effects may be elicited via non-cannabinoid receptor-dependent mechanisms. More research is necessary to fully elucidate the role of each compound in modulating sleep processes.

Cannabinoids, Endocannabinoids and Sleep

Sleep is a vital function of the nervous system that contributes to brain and bodily homeostasis, energy levels, cognitive ability, and other key functions of a variety of organisms. Dysfunctional sleep induces neural problems and is a key part of almost all human psychiatric disorders including substance abuse disorders. The hypnotic effects of cannabis have long been known and there is increasing use of phytocannabinoids and other formulations as sleep aids. Thus, it is crucial to gain a better understanding of the neurobiological basis of cannabis drug effects on sleep, as well as the role of the endogenous cannabinoid system in sleep physiology. In this review article, we summarize the current state of knowledge concerning sleep-related endogenous cannabinoid function derived from research on humans and rodent models. We also review information on acute and chronic cannabinoid drug effects on sleep in these organisms, and molecular mechanisms that may contribute to these effects. We point out the potential benefits of acute cannabinoids for sleep improvement, but also the potential sleep-disruptive effects of withdrawal following chronic cannabinoid drug use. Prescriptions for future research in this burgeoning field are also provided.

The emerging role of the endocannabinoid system in endocrine regulation and energy balance

During the last few years, the endocannabinoid system has emerged as a highly relevant topic in the scientific community. Many different regulatory actions have been attributed to endocannabinoids, and their involvement in several pathophysiological conditions is under intense scrutiny. Cannabinoid receptors, named CB1 receptor and CB2 receptor, first discovered as the molecular targets of the psychotropic component of the plant Cannabis sativa, participate in the physiological modulation of many central and peripheral functions. CB2 receptor is mainly expressed in immune cells, whereas CB1 receptor is the most abundant G protein-coupled receptor expressed in the brain. CB1 receptor is expressed in the hypothalamus and the pituitary gland, and its activation is known to modulate all the endocrine hypothalamic-peripheral endocrine axes. An increasing amount of data highlights the role of the system in the stress response by influencing the hypothalamic-pituitary-adrenal axis and in the control of reproduction by modifying gonadotropin release, fertility, and sexual behavior. The ability of the endocannabinoid system to control appetite, food intake, and energy balance has recently received great attention, particularly in the light of the different modes of action underlying these functions. The endocannabinoid system modulates rewarding properties of food by acting at specific mesolimbic areas in the brain. In the hypothalamus, CB1 receptor and endocannabinoids are integrated components of the networks controlling appetite and food intake. Interestingly, the endocannabinoid system was recently shown to control metabolic functions by acting on peripheral tissues, such as adipocytes, hepatocytes, the gastrointestinal tract, and, possibly, skeletal muscle. The relevance of the system is further strenghtened by the notion that drugs interfering with the activity of the endocannabinoid system are considered as promising candidates for the treatment of various diseases, including obesity.

Cross-tolerance development to the prolongation of pentobarbitone-induced sleep by delta 8-tetrahydrocannabinol and 11-hydroxy-delta 8-tetrahydrocannabinol in mice

Repeated administration (5 mg kg-1 day-1 i.v.) of delta 8-tetrahydrocannabinol and its active metabolite, 11-hydroxy-delta 8-tetrahydrocannabinol caused tolerance to develop to their prolonging effect on pentobarbitone-induced sleep in mice. Reciprocal cross-tolerance also developed after seven daily doses of these cannabinoids. The magnitude of the tolerance developed by the metabolite was greater than that by delta 8-tetrahydrocannabinol. The results suggest that 11-hydroxy-delta 8-tetrahydrocannabinol plays an important role both in the sleep-prolonging effect of delta 8-tetrahydrocannabinol and its tolerance development.

Difference in tolerance development of hypothermia and pentobarbital-induced sleep prolongating effect of 11-hydroxy-delta 8-tetrahydrocannabinol and 11-oxo-delta 8-tetrahydrocannabinol in mice

Daily administration (5 mg/kg i.v.) of 11-hydroxy-delta 8-tetrahydrocannabinol or 11-oxo-delta 8-tetrahydrocannabinol as well as delta 8-tetrahydrocannabinol quickly induced tolerance to their hypothermic effects in mice. Tolerance also developed to their pentobarbital-induced sleep prolongating effects. However, the degrees of tolerance development differed from one another. The sleeping times after the 8th injection of these cannabinoids were still significantly longer than those of the controls when no hypothermia was induced.

Changes in body temperature after administration of antipyretics, LSD, delta 9-THC, CNS depressants and stimulants, hormones, inorganic ions, gases, 2,4-DNP and miscellaneous agents

This survey concludes a series of complications of data from the literature, primarily published since 1965, on thermoregulatory effects of antipyretics in afebrile as well as in febrile subjects, LSD and other hallucinogens, cannabinoids, general CNS depressants, CNS stimulants including xanthines, hormones, inorganic ions, gases and fumes, 2,4-dinitrophenol and miscellaneous agents including capsaicin, cardiac glycosides, chemotherapeutic agents, cinchona alkaloids, cyclic nucleotides, cycloheximide, 2-deoxy-D-glucose, dimethylsulfoxide, insecticides, local anesthetics, poly I:poly C, spermidine and spermine, sugars, toxins and transport inhibitors. The information listed includes the species used, route of administration and dose of drug, the environmental temperature at which the experiments were performed, the number of tests, the direction and magnitude of body temperature change and remarks on the presence of special conditions such as age or lesions, or on the influence of other drugs, such as antagonists, on the response to the primary agents.

Food and water intake, meal patterns and activity of obese and lean Zucker rats following chronic and acute treatment with delta9-tetrahydrocannabinol

A series of experiments investigated the effects of delta9-THC on food and water intakes and wheel-running activity of Zucker rats. Following chronic drug treatment (15 days), food and water intakes of all rats were suppressed, but intakes and body weights of the obese rats recovered more slowly than those of lean rats. Acute effects of the drug (24 hr) were examined using techniques of meal pattern analysis and were discussed in relation to known patterns of anorectic drug action. The drug-induced anorexia was both delayed and of short duration, with no rebound eating observed for either solid or liquid diets. Both feeding rate and meal size were reduced, but meal frequency was transiently increased. The time of onset of the first meal remained unchanged. The time course of the suppression of feeding was paralleled by a suppression in running-wheel activity. These findings suggest that the drug-induced reduction in food and water intake may be the result of a decreased level of arousal.

Screening hallucinogenic drugs II. Systematic study of two behavioral tests

The effects of hallucinogenic and nonhallucinogenic drugs were studied on two behavioral tests: (1) discriminated Sidman avoidance, using modified Bovet-Gatti profiles, which have been proposed as specific in detecting hallucinogenic activity and (2) a drug discrimination experiment. By the first method, the "hallucinogenic profile" was obtained with both hallucinogenic and nonhallucinogenic drugs and, at least as used here, was not a suitable screening method. In the drug discrimination experiment, data from the present study along with other available evidence suggest the potential value of this method for drug screening procedures.

Interaction between delta(9)-tetrahydrocannabinol and d-amphetamine

d-Amphetamine increases the motor activity at a dose range of 0.5-4 mg/kg. delta(9)-Tetrahydrocannabinol (THC) diminishes this effect dose-dependently. Also, the hyperthermia caused by 5 mg/kg d-amphetamine is antagonized by THC, whereas the d-amphetamine induced stereotype movements (above 4 mg/kg) are prolonged by the cannabinoid. THC and d-amphetamine both reduce the food and water intake and the normal development body weight of rats. In combination the two substances have an additive effect. Rats treated with 5 mg/kg d-amphetamine show a significant enhancement of the dopamine (DA) concentration (26%) in the brain stem 2 h p.i. Pretreatment with 10 mg/kg THC, which also causes an increase of DA by 15%, raises the DA content by 50%. Norepinephrine (NE) in the brain stem and hypothalamus is reduced by d-amphetamine but THC has no effect on the concentration of this monoamine. After subchronical treatment with THC tolerance is demonstrable to all THC effects tested. But there is no cross tolerance between delta(9)-THC and d-amphetamine since the pharmacological as well as the biochemical effects of d-amphetamine occur despite the subchronical treatment with THC.

Anorectic activity of prostaglandin precursors

1 Intraperitoneal and intragastric (i.g.) administration of prostaglandin precursors arachidonic (2 mg, 15 mg/kg, i.p; 30 mg/kg i.g.), linolenic (100 mg/kg i.p.; 200 mg/kg, i.g.) and linoleic (15, 100 mg/kg, i.p.; 100 mg/kg, i.g.) acids to 22 h food-deprived rats inhibits food intake. 2 This anorexia is similar to that induced by prostaglandin F2alpha (1 mg/kg, i.p.). 3 At anorectic doses these fatty acids do not cause pyrexia, in fact arachidonic acid causes hypothermia. 4 Prior treatment with indomethacin (15 mg/kg) and paracetamol (50 mg/kg) specifically reverses the anorexia and the behavioural satiety induced by the three fatty acids, while not affecting prostaglandin F2alpha-induced suppression of food intake. 5 Results of the present experiments suggest that both physiological and pharmacological modification of appetite could be brought about through an effect on prostaglandin generating systems.