Prenatal delta-9-tetrahydrocannabinol in the rat: effects on postweaning growth

Either 15 or 30 mg/kg of delta-9-tetrahydrocannabinol (delta-9-THC) was administered from Day 2 through Day 22 of gestation. Pair-fed and nontreated groups served as controls and all treated and control litters were fostered at birth to untreated dams. When weighed at 57-60 days of age, pair-fed controls were significantly heavier than the nontreated, whereas the treated animals were intermediate between the controls. These findings are discussed with respect to nutritional studies that have reported postnatal growth enhancement following prenatal maternal undernutrition and the possibility that prenatal delta-9-THC inhibits this effect.

Induction of cognitive impairment by scopolamine and noncholinergic agents in rhesus monkeys

In primates, treatment with scopolamine impairs performance of a spatial delayed response task in a way which mimics deficits seen spontaneously in aged primates and demented patients. Despite their efficacy in reversing scopolamine induced disruption, the effects of cholinergic agonists on cognition in aged primates and dements are unimpressive, suggesting that other neurotransmitter systems are also involved in this type of deficit. We have induced a scopolamine-like impairment of spatial delayed response performance in rhesus monkeys using phencyclidine (0.1-0.2 mg/kg i.m.), lorazepam (0.4-0.6 mg/kg s.c.) or tetrahydrocannabinol (1-4 mg/kg p.o.), but not amphetamine (0.1-0.4 mg/kg i.m.), yohimbine (0.1-1.0 mg/kg i.m.) or morphine (2-4 mg/kg i.m.). Our findings suggest that disruption of specific neurotransmitter systems other than acetylcholine may contribute importantly to cognitive decline in aging and dementia.

Synthesis and pharmacological evaluation of amino, azido, and nitrogen mustard analogues of 10-substituted cannabidiol and 11- or 12-substituted delta 8-tetrahydrocannabinol

The synthesis of a variety of novel 10-substituted cannabidiol (CBD) and 11- or 12-substituted delta 8-tetrahydrocannabinol (delta 8-THC) analogues containing amino, alkylamino, azido, or a N,N-bis(2-chloroethyl)amino functional group is described, as well as their pharmacological evaluation in mice. These analogues, which possess only a portion of the full pharmacological spectrum of activity of delta 9-THC, indicate that cannabinoid-mediated reduction of spontaneous locomotor activity, hypothermia, antinociception, and/or catalepsy need not be produced simultaneously, possibly suggesting the existence of more than one mechanism of action. The 10-substituted CBD analogues 3, 4, and 5 with an ethylamino, propylamino, or azido functional group, respectively, proved to be largely inactive, except for the production of central nervous system (CNS) depression concomitant with toxicity. Toxicity and CNS depression may be related phenomena in these nitrogenous compounds since 12-amino and 12-ethylamino analogues (8 and 11) of delta 8-THC also proved to be very toxic. Antinociceptive and hypothermic responses (without reduction of motor activity) were observed at a dose of 10 mg/kg of the 11-ethylamino analogue (9) of delta 8-THC, while a dose of 50 mg/kg of the nitrogen mustard 11-[N,N-bis(2-chloroethyl)amino]-delta 8-THC (12) was necessary to produce any observable pharmacological effect. When selected analogues were evaluated for antagonistic properties, they failed to attenuate the effects of delta 9-THC. Some nitrogen mustard analogues were capable of producing minimal pharmacological effects after either peripheral or direct CNS administration; however, these analogues also failed to attenuate the effects of delta 9-THC either immediately after administration or 24-48 h later.

Maternal age does not affect tetrahydrocannabinol's in utero actions in rats

The potential contribution of maternal age to tetrahydrocannabinol's (THC) in utero effects in rats was studied. Pregnant animals were intubated with 25, 10 or 0 mg/kg of THC from gestation day six to parturition. Animals in the 10 and 0 mg/kg groups were pair fed to those given the 25 mg/kg dose. Each series of doses was administered to females three, four or six months of age. THC lowered maternal weight gain and weights of offspring at birth and at 21 days of age, but did not affect litter size, spontaneous alternation or passive avoidance learning in offspring. Increased maternal age was associated with smaller litter size and lower birth weight and weight at 21 days, but did not interact significantly with THC.

Effects of low doses of alcohol on delta-9-tetrahydrocannabinol's effects in pregnant rats

Pregnant rats were intubated with 50 mg/kg of delta-9-tetrahydrocannabinol (THC) or with THC plus alcohol to determine if a low dose of alcohol (1 g/kg) would significantly increase blood levels of THC. On the basis of this study, a second study was conducted in which pregnant rats were intubated with THC (50, 25 or 0 mg/kg) plus alcohol (2, 1 or 0 g/kg) from gestation day six to parturition. THC reduced birth weights but did not significantly affect litter size or passive avoidance learning. Alcohol did not have a significant effect on offspring birth weight nor did it interact with THC to affect offspring.

[Cannabis: a harmless drug?]

Summarizing the literature of the past 25 years, we present a survey of the pharmacological effects of cannabis, which includes the pharmacological particularities of cannabis as a composition of substances with tetra-hydro-cannabinol as main component, the experimentally proved effects on animal cells, the experimentally and clinically proved damages to the central nervous system, respiratory tract, immune system and procreative system. The survey results in a warning: brain damage and dependency can be caused by cannabis and the resulting social consequences of an increasing consumption should not be underestimated.

The effects of prenatal exposure to delta-9-tetrahydrocannabinol on the rest-activity cycle of the preweanling rat

Either 15 or 50 mg/kg of delta-9-tetrahydrocannabinol (delta-9-THC) was administered from Day 2 through Day 22 of gestation. Pair-fed (0 mg/kg) and nontreated groups served as controls and all treated and control litters were fostered at birth to untreated dams. To examine whether delta-9-THC produces effects on the rest-activity cycle of the offspring, groups of 3 littermates from each of the treated and control groups were tested for an 8 hr observation period on electronic activity monitors at 17, 22 and 30 days of age. Whereas all treated and control groups showed age-dependent changes in activity, neither activity level nor the rest-activity pattern were affected by delta-9-THC. These findings are discussed in relation to neurobehavioral studies of activity changes following prenatal exposure to cannabis.

Effects of delta-9-tetrahydrocannabinol on in vitro energy substrate metabolism in mouse and rat testis

In this in vitro radiorespirometric study, the effects of delta-9-tetrahydrocannabinol (THC) on glucose and fructose metabolism in the rat and mouse testes were compared. In the rat testis, THC caused a dose-dependent decrease of 15, 18, 20 and 25% in glucose metabolism with 0.1, 0.2 and 0.3 mM concentrations. Similarly, a 39% inhibition in fructose metabolism was observed when rat testes were exposed to 0.3 mM THC. The comparative studies with mouse testis indicated that 0.1, 0.2 and 0.3 mM THC produced a 4, 12 and 30% decrease in glucose utilization where as a much greater decrease of 13, 30 and 41% in fructose utilization was observed with the same doses of THC. On the basis of these observations in these two animal models, it is concluded that THC has the ability to inhibit energy substrates utilization in the rat and mouse testis. This inhibition of cellular energetics may, in part, be responsible for most of the gonadal effects of THC.

Interactive effects of chronic phencyclidine and delta 9-tetrahydrocannabinol on spermatogenesis in mice

In this study, the combined effects of chronic phencyclidine (PCP) and delta 9-tetrahydrocannabinol on spermatogenesis in mice were examined. Mice were treated with THC (50 mg/kg, PO) and PCP (15 mg/kg, IP) alone or in combination for 16 days and with PCP alone for 35 days. THC had a significant effect on spermatogenesis and decreased the number of all germinal cells. PCP, on the other hand, affected all germinal cells except spermatids after 35 days of treatment. Combination of THC and PCP treatment caused a significant decrease in resting and pachytene spermatocytes. Similarly, combination of these two drugs caused a significant increase in cauda epididymal abnormal sperms. These results suggest that THC and PCP may cause greater disruption in spermatogenesis when they are abused together.

Immunization against prostaglandins reduces delta 1-tetrahydrocannabinol-induced catalepsy in mice

Immunization of mice with a thyroglobulin-prostaglandin E2 (PGE2) conjugate produced animals with measurable blood levels of anti-PGE2 antibodies. When these mice were challenged with delta 1-tetrahydrocannabinol (THC) (20 mg/kg), they showed a greatly diminished cataleptic response as compared with control animals. This observation further supports a hypothesis on the mechanism of action of THC in which eicosanoids, such as PGE2, are early mediators. Based on the likelihood that antibodies were not present in the central nervous system, it is suggested that the initial site of action of THC may be at one or more peripheral locations. The transport of peripheral PGE2 or other eicosanoids to the brain would result in the eventual manifestation of THC action at this site.

Delta-9-tetrahydrocannabinol-induced catalepsy in mice is enhanced by pretreatment with flurazepam or chlordiazepoxide

Pretreatment with flurazepam (3 mg/kg s.c.) or chlordiazepoxide (5.5-30 mg/kg s.c.) at an ambient temperature of 34 degrees C, markedly enhanced the cataleptic response of mice to delta-9-tetrahydrocannabinol (THC; 5-20 mg/kg i.p.) as measured in a bar test. Also, the incidence of loss of the righting response was significantly greater in mice receiving a subhypnotic dose of flurazepam (0.3-3 mg/kg s.c.), followed by THC (5-20 mg/kg i.p.), than in animals receiving THC preceded by saline. Loss of the righting response was not associated with any gross reduction in skeletal muscle tone (inclined screen and wire grip tests) and it was proposed that the animals were not anaesthetized but instead could be placed on their backs because flurazepam had enhanced the cataleptic effect of THC. Loss of the righting response produced in mice by pentobarbitone (60 mg/kg i.p.) or by a large dose of flurazepam (300 mg/kg s.c.) was associated with a marked loss of muscle tone and probably indicated the induction of anaesthesia. It is possible that THC interacts with benzodiazepines by increasing synaptic concentrations of gamma-aminobutyric acid (GABA). However, many other possible mechanisms exist and these cannot yet be excluded.

Inhibition of the cataleptic effect of tetrahydrocannabinol by other constituents of Cannabis sativa L

Tetrahydrocannabinol (THC) induced catalepsy in mice, whereas a cannabis oil (6.68% w/w THC), four cannabinoids and a synthetic mixture did not. Cannabinol (CBN) and olivetol inhibited THC-induced catalepsy in the mornings and the evenings, but cannabidiol (CBD) exhibited this effect only in the evenings. A combination of CBN and CBD inhibited THC-induced catalepsy equal to that of CBN alone in the mornings, but this inhibition was greater than that produced by CBN alone in the evenings.

Perinatal exposure to cannabinoids alters neurochemical development in rat brain

Adult female rats received daily oral doses of delta 9-tetrahydrocannabinol (delta 9-THC), delta 8-THC and cannabidiol (CBD) throughout gestation and lactation. The offspring were sacrificed at various ages and tissue samples of cerebral cortex and striatum were assayed for alpha 1-adrenergic and D2-dopaminergic receptors, respectively. In addition, tyrosine hydroxylase activity was determined in the striatum. The Kd for ligand binding to alpha 1 receptors in the cerebral cortex was significantly increased in 10-day-old offspring exposed to CBD. Significant increases in the Bmax of these receptors occurred at 20 days of age following perinatal exposure to delta 9-THC or delta 8-THC. Exposure to CBD increased the Kd of D2 receptors in the striatum of 10 and 20-day-old offspring compared to control. There were no significant treatment effects on the Bmax of D2 receptors in the striatum at any age. Tyrosine hydroxylase activity was significantly decreased only at 60 days of age in offspring exposed to delta 8-THC or CBD. These results differ from those previously reported with a crude marihuana extract, suggesting that changes in the development of brain catecholamine mechanisms resulting from perinatal exposure to marihuana extracts may be due to an additional constituent of the extract, interactions between specific cannabinoids or other unknown factors.

Effects of delta 9-tetrahydrocannabinol, phenobarbital, and their combination on pregnancy and offspring in rats

delta 9-THC, sodium phenobarbital, or a combination of these drugs, were administered to pregnant mice on gestation days 6 to parturition. Levels of delta 9-THC in blood approximated levels attained in humans after smoking one to two marijuana cigarettes. Blood cannabinoid levels in mice were not significantly elevated by concurrent drug administration. Both drugs significantly reduced litter size and weight per pup at birth, but the combination of these drugs did not affect these outcomes to a significantly greater degree than either drug by itself. Phenobarbital but not delta 9-THC increased resorption rate.

A species comparison of the toxicity of nabilone, a new synthetic cannabinoid

Acute, subchronic, and chronic studies were conducted in various species to evaluate and compare the toxicity of nabilone, a new synthetic 9-ketocannabinoid that is orally effective for the treatment of nausea and vomiting induced by cancer chemotherapy agents. The oral LD50 in mice and rats for nabilone formulated as a polyvinylpyrrolidone (PVP) codispersion was in excess of 1000 mg/kg. Among nonrodents, rhesus monkeys had a higher tolerance to the CNS depression induced by single oral doses of nabilone-PVP than did dogs. Rats fed dietary mixtures of nabilone-PVP which provided approximate daily nabilone doses of 1 to 93 mg/kg tolerated treatment for 3 months with no deaths. Treatment-related changes (at doses greater than or equal to 5 mg/kg) were limited to reduced body temperature, slight-to-moderate decreases in weight gain, and behavioral changes (e.g., hyperactivity, hyperirritability to touch, and hypoactivity). All dogs treated for 3 months with daily oral doses of up to 1.0 mg/kg survived; treatment-related effects were limited to transient episodes of ataxia and anorexia. Nabilone treatment of rats and dogs for 3 months produced no evidence of systemic toxicity in the clinical chemistry, hematology, or pathology parameters examined. Chronic treatment of dogs with daily oral doses of nabilone-PVP equal to 0.5, 1.0, or 2.0 mg of nabilone/kg produced cumulative toxicity; by the end of 7 months, 2, 6, and 7 dogs in the respective dose groups had died. In a number of instances, death was preceded by one or more convulsive episodes. In contrast to the dog, the toxic potential of nabilone was minimal in rhesus monkeys treated with nabilone-PVP for 1 year at daily oral nabilone doses of up to 2.0 mg/kg. The enzymatic reduction of the 9-keto group of nabilone to form carbinol metabolites was a major metabolic pathway for nabilone in dogs but not in rhesus monkeys. The carbinols were long-lived metabolites in the plasma of dogs and accumulated in the plasma compartment with time. Furthermore, the carbinol metabolites were found to concentrate in the brain tissues of treated dogs. Although the precise mechanism for this marked species difference in chronic toxicity is not known, the metabolic differences responsible for the presence of the carbinol metabolites at high concentrations in the plasma and brain over time may play a role in the toxicity observed in the dog.

Neonatal administration of delta-9-tetrahydrocannabinol (THC) alters the neurochemical response to stress in the adult Fischer-344 rat

Fischer-344 rat pups were injected with either 10 mg/kg delta 9-tetrahydrocannabinol (THC) or vehicle on postnatal days 4,6 and 8. Pups were then allowed to mature. On day 129 of age rats were exposed to a stress paradigm which consisted of inescapable electric foot-shock administered at 1 mA for 15 sec daily for 8 days. Analgesia induced by foot-shock was measured by tail withdrawal from 55 degree C water. On the 9th day rats were exposed to the shock environment only. Fifteen minutes following measurement of tail withdrawal, animals were sacrificed. Plasma corticosterone and prolactin were measured. Levels of norepinephrine, dopamine and 5-hydroxytryptamine and metabolites were determined in frontal cortex, hippocampus and hypothalamus. Neonatal exposure to THC produced an increase in baseline tail withdrawal latency. No effect of THC exposure was seen on acute stress-induced analgesia. Rats exposed to THC required a greater number of conditioning trials to develop conditioned analgesia than animals treated neonatally with vehicle. The conditioned stress increased plasma corticosterone without affecting prolactin. Stress increased hypothalamic 5HT and 5HIAA while decreasing 5HT turnover in this area. Dopamine and DOPAC levels in the hypothalamus and frontal cortex were increased by stress; dopamine turnover in the frontal cortex was elevated by stress. Neonatal THC and stress elevated norepinephrine above control levels in the hypothalamus, while increasing 5HT in the hippocampus and frontal cortex. The stress-induced increase in DOPAC in the frontal cortex was decreased by THC exposure. These data suggest that long-term neurochemical changes may occur with neonatal administration of THC.(ABSTRACT TRUNCATED AT 250 WORDS)

Nabilone versus prochlorperazine for control of cancer chemotherapy-induced emesis in children: a double-blind, crossover trial

In a randomized, double-blind, crossover trial, nabilone was compared to prochlorperazine for control of cancer chemotherapy-induced emesis in 30 children 3.5 to 17.8 years of age. All subjects received two consecutive identical cycles of chemotherapy with the trial antiemetics given in accordance to a body weight-based dosage schedule beginning eight to 12 hours before treatment. The overall rate of improvement of retching and emesis was 70% during the nabilone and 30% during the prochlorperazine treatment cycles (P = .003, chi 2 test). On completion of the trial, 66% of the children stated that they preferred nabilone, 17% preferred prochlorperazine, and 17% had no preference (P = .015, chi 2 test). Major side effects (dizziness, drowsiness, and mood alteration) were more common (11% v 3%) during the nabilone treatment cycles. CNS side effects appeared to be dose related and were most likely to occur when the nabilone dosage exceeded 60 micrograms/kg/d, but individual tolerance to nabilone varied considerably. Lower dosages of nabilone were associated with equivalent efficacy and no major side effects. Nabilone appears to be a safe, effective, and well-tolerated antiemetic drug for children receiving cancer chemotherapy. Although major side effects may occur at higher dosages, nabilone is preferable to prochlorperazine because of improved efficacy.

Factors affecting the response of the female rat reproductive system to cannabinoids

Chronic oral administration of either crude marihuana extract (CME) or delta 9-tetrahydrocannabinol (THC) to female Fischer rats for 64-72 days, at a dose approximating heavy usage by humans, reduces food intake by about 8%. Pair-feeding studies demonstrate that this decreased food intake accounts for previously described decreases in uterine and ovarian weights, which are much more affected by food restriction than is body weight. THC-treated rats lost weight initially which was not regained. Pair-fed rats gained only about one-half of the weight of the untreated control or vehicle-treated control rats over a 64-day period. Although long-term cannabinoid administration leads to tolerance and the resumption of the estrous cycle, the onset of estrus is often delayed when cannabinoid is administered 5-6 hr before the proestrus luteinizing hormone (LH) surge. Our results indicate that although chronic exposure to cannabinoids can continue to affect the rat estrous cycle, they do not have a direct effect on growth of the reproductive organs. The results reemphasize the need for adequate nutritional controls in marihuana and other toxicological research.

A major metabolite of delta 1-tetrahydrocannabinol reduces its cataleptic effect in mice

The results described here demonstrate that THC-induced catalepsy in mice can be substantially inhibited by the prior administration of delta 1-THC-7-oic acid, the major metabolite of THC in most species including humans. This raises the possibility that the intensity and duration of action of THC may depend to a large degree on the levels of this metabolite at the sites of action.

Species specificity in the metabolism of nabilone. Relationship between toxicity and metabolic routes

The disposition of 14C-nabilone has been examined in dogs and monkeys; it is rapidly absorbed and extensively metabolized in both species. A metabolic pathway initiated by the stereoselective enzymic reduction of the 9-keto moiety of nabilone was of major importance in the biotransformation of nabilone in the dog but was only a minor pathway in the monkey. The resulting long half-lived carbinol metabolites accounted for 77% of the circulating 14C in dog but for only 19% in monkey, 48 h after drug administration. Accumulation of carbinol metabolites in brain tissue was observed in dogs, with 24 h brain concentrations being five to six times higher than the plasma concentrations. No accumulation of carbinol metabolites, nabilone or of 14C occurred in the brain of monkeys. Accumulation of the carbinol metabolites in brain tissue has been implicated as the causative factor for the CNS toxicity observed in dogs treated chronically with nabilone. Comparison of nabilone pharmacokinetics in dog and humans showed the dog to be unique in producing high levels of carbinol metabolites, so that monkey appeared to be a more appropriate model than dog for pre-clinical toxicological and safety studies. Studies with liver 15,000 g supernatants indicated that the enzymic reduction of nabilone to its carbinol metabolite was a viable metabolic pathway in rat, dog and monkey, so that a distinct species difference exists between dog and monkey in the subsequent metabolism and/or elimination of these carbinol metabolites.

Inhibition of natural killer cell function by marijuana components

The extent of modulation of host resistance mechanisms by marijuana components is not fully understood. Natural killer (NK) cells are a subpopulation of lymphoid cells and are important in host resistance mechanisms against malignant cells, virus-infected cells, and possibly pathogenic bacteria and fungi. We report that the marijuana component delta-9-tetrahydrocannabinol (THC) injected into mice results in a suppression of splenic NK activity. Furthermore, THC and the hydroxylated metabolite 11-hydroxy-delta-9-tetrahydrocannabinol (11-hydroxy-THC) suppress the NK activity of cultured murine splenocytes in a dose-dependent manner (range 1 X 10(-5) to 3.2 X 10(-5) M) without diminishing NK cell viability. The hydroxylated derivative appears to possess a more potent suppressive effect, in that it suppresses at lower concentrations than THC does and requires a shorter incubation time with the effector cells for its suppressive action. Purification of NK cells by Percoll density-gradient centrifugation suggests that both cannabinoids act directly on the natural killer cell population, resulting in suppression. Studies involving target binding analysis and calcium ionophore experiments suggest that cannabinoids do not suppress NK cell killing by the inhibition of effector/target binding or by disruption of calcium ion flux. These results suggest that two principal psychoactive cannabinoids can suppress natural killer cell function by interacting directly with the killer cells and disrupting cellular events postbinding and during the programming for lysis. Furthermore, the data suggest different modes of action for THC and the hydroxylated metabolite.

Behavioral effects of THC as a function of environment and prior drug experience

Holtzman albino rats were divided into 4 groups, and on 5 consecutive days each group was exposed to one of 4 conditions. The drug-adapted group was given delta-9-tetrahydrocannabinol (THC) (0.0, 0.5, 2.5 or 5.0 mg/kg PO) in their home cages, while the environment-adapted group was given vehicle and placed for one hr in the chamber where they were later tested. The naive group was given vehicle in their home cages and the drug + environment adapted group was given THC and placed in the test chamber. One week later, all rats were given either 0.0, 0.5, 2.5, or 5.0 mg/kg THC and placed in the test chamber where standing, sitting, and behavioral activity were measured. The results showed that the behavioral effects of THC are a function of environmental familiarity in rats who are drug naive but not in rats given prior exposure to THC.

Effects of delta-9-tetrahydrocannabinol, chlordiazepoxide (Librium), and their combination on pregnancy and offspring in mice [correction of rats]

Delta-9-tetrahydrocannabinol (THC), chlordiazepoxide hydrochloride (Librium) or a combination of these drugs, were administered to pregnant mice on gestation days 6 to parturition. Levels of THC in blood were dose-related and approximated levels attained in humans after smoking one to two marijuana cigarettes. Blood cannabinoid levels in mice were elevated by concurrent administration of chlordiazepoxide. Maternal weight gain was significantly reduced by THC but not by chlordiazepoxide. Neither drug affected implantations, but THC significantly increased resorptions. Both THC and chlordiazepoxide decreased fetal weight. There was no indication of synergism between the two drugs for any of the measures examined in this study.