Enzymatic changes in the male reproductive organs by delta-9-tetrahydrocannabinol

Like most psychoactive agents, cannabis and its active component delta-9-tetrahydrocan-nabinol (Δ⁹-THC) have been reported to affect the neuroendocrine axis in animals. The effect of Δ⁹-THC on some of the functionally important enzymes of the male reproductive organs are reported. The study indicates that Δ⁹-THC reduces the activities of the enzymes, β-glucuronidase, α-glucosidase acid phosphatase and fructose-6-phosphatase in a dose related manner in the testis, prostate as well as in the epididymis. It may be concluded that Δ-THC may interfere with the normal functioning of the male reproductive organs.     

Tetrahydrocannabinol and acetylcholinesterase

Recent evidence suggests that the psychoactive effect of delta-9-tetrahydrocannabinol (Δ⁹-THC), the major psychoactive constituent of marihuana, may be mediated through an alteration of cholinergic neurotransmission. One possible mechanism by which Δ⁹-THC could have its effect is by affecting acetylcholinesterase (AChE) and there is evidence that has suggested that this may be an important mechanism. The results reported in the present study have shown that there is no physiologically important interaction between AChE and Δ⁹-THC or its metabolites that could explain its psychoactive effects or the profound clinical depression observed when human marihuana users are administered the cholinesterase inhibitor physostigmine.     

Role of the central autonomic nervous system in the hypotension and bradycardia induced by (-)-delta 9-trans-tetrahydrocannabinol

(-)-Δ⁹-trans-Tetrahydrocannabinol (Δ⁹-THC), when given intravenously (2 mg kg^?1) to cats, produced marked decreases in blood pressure and heart rate which developed gradually and were of prolonged duration. Cervical spinal transection (C₁-C₂) abolished these effects whereas surgical removal of neurogenic tone to the myocardium selectively eliminated the bradycardia. Bilateral vagotomy alone did not modify the action of Δ⁹-THC upon heart rate or blood pressure. Recordings of spontaneous sympathetic outflow in the inferior cardiac nerve indicated a rapid reduction in neural discharge rate after Δ⁹-THC administration. These observations support the hypothesis that Δ⁹-THC produces a cardiodecellerator and hypotensive effect by acting at some level within the sympathetic nervous system. Experiments conducted to investigate transmission in the superior cervical and stellate ganglia demonstrated that Δ⁹-THC did not alter ganglionic function. Also, responses to intravenous isoprenaline and noradrenaline were unchanged which suggested that Δ⁹-THC did not interact with α- or β- adrenoceptors. The possible action of Δ⁹-THC on central sympathetic structures was investigated by perfusion of Δ⁹-THC into the lateral cerebral ventricle. Δ⁹-THC so administered produced a significant reduction in heart rate without a substantial lowering of blood pressure. Tritiated or ¹⁴C-Δ⁹-THC perfused into the lateral ventricle demonstrated that the amount of radioactive compound passing into the peripheral circulation was insignificant and could not account for the decrease in heart rate. The current data are in agreement with the proposal that Δ⁹-THC produces cardiovascular alterations by an action on the central nervous system which results in a decrease in sympathetic tone.     

Acute and subacute inhalation toxicity of Turkish marihuana, cannabichromene, and cannabidiol in rats.

Fischer rats were exposed to a single daily dose of smoke from Turkish marihuana containing 1.2% cannabidiol (CBD) + cannabichromene (CBCH) and 0.25% of Δ⁹-tetrahydrocannabinol (Δ⁹-THC) or smoke from placebo marihuana impregnated with 0.6% (CBD or CBCH, respectively) 5 days/week for 17–25 days. An automatic inhalator presented cannabinoid doses of 1, 1.5, and 2 mg/kg from Turkish marihuana or 0.6, 0.8, and 1.2 mg/kg from CBD- or CBCH-marihuana. A 50% delayed lethal toxicity occurred in both sexes at the high dose of Turkish marihuana with no deaths in CBD, CBCH, or placebo groups. Hypoactivity was observed by the second week among rats exposed to smoke from Turkish marihuana or placebo marihuana impregnated with CBD or CBCH. No hyperactivity or hypersensitivity was evident after tolerance developed to depressive signs. Turkish marihuana smoke suppressed growth rates and respiration rates more than smoke containing CBD or CBCH without Δ⁹-THC. Hematological variations were more closely associated with CBCH but organ-weight changes were related to Turkish marihuana and CBD. The only drug-related histopathological finding was seminiferous tubule degeneration with interference in sperm maturation. This dose-related effect was most severe in CBD-treated rats. Estimated LD50 values based on cannabinoid content were 10 mg/kg for Turkish marihuana smoke and approximately 35 mg/kg for smoke containing CBD or CBCH.     

Weight and activity in male mice after daily inhalation of cannabis smoke in an automated smoke exposure chamber

An automatic smoking machine capable of delivering marihuana smoke to groups of 10 mice at a time at a constant concentration of Δ⁹-THC is described. In all cases the flow rate (50 ml s^?1 or 100 ml ^s-1) of a smoke: air mixture, and the dilution factor (1:20 or 1:10 smoke:air) was adjusted to give the same equilibrium concentration of Δ⁹-THC in the chamber atmosphere. At a concentration of 0–123 mg Δ⁹-THC litre^?1 of exposure chamber atmosphere (1:20 smoke: air; 100 ml s^?1 flow rate), a seven day schedule of 20 min daily treatments significantly decreased activity of the marihuana-treated animals by the sixth day over both air and placebo smoke controls. This concentration and exposure schedule failed to affect weight gain during this same period. A significant decrease in activity, although not as great as in the marihuana-treated group, was also seen in the placebo control group compared with the air control animals, indicating the need for a smoke control group in all experiments involving the administration of marihuana via inhalation. An exposure period of 102 min, with marihuana smoke diluted with air 1:10 (50 ml ^s-1 flow rate), at the same equilibrium concentration of 0·123 mg Δ⁹-THC litre^?1, resulted in a mortality of 90% following administration or within 48 h. 102 min of exposure to an atmosphere of placebo smoke at a smoke:air dilution of 1:10 (50 ml ^s-1 flow rate), resulted in no mortality.     

Decreased basal endogenous opioid levels in diabetic rodents: effects on morphine and delta-9-tetrahydrocannabinoid-induced antinociception

We have previously demonstrated synergy between morphine and Δ⁹-tetrahydrocannabinol (Δ⁹-THC) in the expression of antinociception in acute pain models and in arthritic models of chronic pain. Our data has been extended to include acute pain in both diabetic mice and rats. In diabetic mice, Δ⁹-THC p.o. was more active in the tail-flick test in the diabetic mouse than in the non-diabetic mouse. Morphine (s.c.) was less potent in diabetic than in non-diabetic mice [6.1 (5.1-7.2) versus 3.2 (2.4-4.1) mg/kg, respectively], an effect previously extensively documented in pre-clinical and clinical testing. In addition, the combination of Δ⁹-THC with morphine produced a greater-than-additive relief of acute pain in mice. In the rat, the induction of the diabetic state decreased the antinociceptive effect of morphine, an effect temporally related to a decreased release of specific endogenous opioids. Conversely, Δ⁹-THC retained the ability to release endogenous opioids in diabetic rats and maintained significant antinociception. Extrapolation of such studies to the clinical setting may indicate the potential for use of Δ⁹-THC-like drugs in the treatment of diabetic neuropathic pain, alone or in combination with very low doses of opioids.     

Effects of marihuana extract on the operant behavior of chimpanzees

Six chimpanzees were trained to panel push under a food reinforcement baseline in which three operant schedules, each associated with a different stimulus, were presented successively. The fixed ratio (FR) reinforcement schedule required the emission of 40 responses for reinforcement. Reinforcement under the differential reinforcement of low rate (DRL) schedule was delivered only when successive responses were spaced by at least 10 sec. During the extinction or time out from positive reinforcement schedule (TO), no responses were reinforced. In Experiment 1, amounts of marihuana extract containing from 0.2 to 4.0 mg/kg (?)-Δ ⁹-trans-tetrahydrocannabinol (Δ ⁹-THC) were orally administered 1 h prior to experimentation. In Experiment 2, 1.0 mg/kg Δ ⁹-THC was orally administered between 1 and 23 h prior to experimental sessions. No disruption of stimulus control or drug effects during TO were observed. Both DRL and FR response suppression occurred at the highest drug dose. Lower Δ ⁹-THC doses produced facilitation of DRL responding up to 12 h following drug administration. Although FR responding was less sensitive, Δ ⁹-THC stimulated FR behavior from 2 to 5 h following drug administration. It was concluded that marihuana has a biphasic effect on food reinforcement schedule controlled operant behavior.     

Catalepsy induced by intrastriatal injections of delta9-THC and 11-OH-delta9-THC in the rat

Intrastriatal injections of Δ⁹-THC and 1 l-hydroxy-Δ⁹-THC induced dose-dependent catalepsy in the rat, the parent compound being more potent than the metabolite. Catalepsy was not induced following intrapallidal injection of either drug. The results suggest that the caudate-putamen could be a “specific site” in the mediation of catalepsy induced by Δ⁹-THC.Intrastriatal amphetamine attenuated Δ⁹-THC-induced catalepsy whereas intrapallidal amphetamine potentiated the effect indicating a complex interaction with dopaminergic systems in the basal ganglia.Δ⁹-THC and the central cholinergic stimulant, RS-86 synergize on administration to either area indicating a possible cholinergic involvement in the phenomenon.     

Inhibition of naloxone-induced withdrawal in morphine dependent mice by l-trans-Δ9-tetrahydrocannabinol

The effects of various doses of l-trans-Δ⁹-tetrahydrocannabinol (Δ⁹-THC) on naloxone-induced withdrawal were studied in mice rendered dependent on morphine by the pellet implantation procedure. When administered i.p., 30 min prior to naloxone, Δ⁹-THC, inhibited the naloxone-induced withdrawal jumping response. Two other signs of morphine withdrawal (defecation and rearing behavior) were also suppressed by Δ⁹-THC. It is suggested that Δ⁹-THC or some of its derivatives may have potential use in narcotic detoxification.     

Antipyretic, analgesic and anti-inflammatory effects of delta 9-tetrahydrocannabinol in the rat

The effects on body temperature produced by graded doses of Δ⁹-tetrahydrocannabinol (Δ⁹-THC) and phenylbutazone were compared in both normal and pyretic rats. Dose related hypothermic responses were produced by the oral administration of Δ⁹-THC in normal animals. Moreover, Δ⁹-THC significantly reduced elevated temperatures in yeast-induced pyretic rats to near normal levels at doses which exhibited little hypothermic activity in normal rats. The oral antipyretic potency of Δ⁹-THC was approximately 2 times that of phenylbutazone. The comparative oral antinociceptive activity of Δ⁹-THC and selected narcotic and non-narcotic analgesics was determined by the increase in response latency to pressure applied to normal and yeast-inflamed paws. Δ⁹-THC administered orally was essentially inactive at dose levels below those producing pronounced central nervous system depression. The oral anti-inflammatory efficacy of Δ⁹-THC was compared to phenylbutazone and acetylsalicylic acid. Δ⁹-THC was ineffective in inhibiting carrageenin-induced edema of the rat paw following acute or chronic administration.     

GABAergic mediation in the inhibition of hippocampal acetylcholine turnover rate elicited by delta 9-tetrahydrocannabinol.

Both intravenous Δ⁹-tetrahydrocannabinol (Δ⁹-THC) and intraseptal muscimol reduce the turnover rate of acetylcholine (TR_ACh) in the hippocampus by 50 and 58%, respectively, without affecting the hippocampal content of ACh. The ACh content and the TR_ACh, in other areas of rat brain examined are unchanged. Bicuculline fails to alter the hippocampal TR_ACh when administered intraseptally but prevents the decreased hippocampal TR_ACh induced by Δ⁹-THC or muscimol. The effect is specific to the septal-hippocampal cholinergic pathway since lesioning the fimbria (2 hr) abolishes the effect. Moreover, neither naltrexone nor destruction of septal dopaminergic nerve terminals with 6-hydroxy-dopamine injected into area A₁₀ prevents the decreased TR_ACh after Δ⁹-THC. This suggests that neither endophinergic nor dopaminergic neurons are involved in the reduction of the TR_ACh in the hippocampas following administration of Δ⁹-THC or muscimol. When the metabolism of γ-aminobutyric acid (TR_GABA) is measured, Δ⁹-THC produces a 2-fold increase in the TR_GABA which is specific for the septum. These results suggest that Δ⁹-THC inhibits TR_ACh in the cholinergic septal-hippocampal pathway by increasing the release of GABA from septal GABAergic interneurons.     

Pharmacological potency of R- and S-3′-hydroxy-Δ9-tetrahydrocannabinol: additional structural requirement for cannabinoid activity

The pharmacological potency of R- and S-3′-hydroxy-Δ⁹-tetrahydrocannabinol (THC) was compared to that of Δ⁹-THC as well as R/S-3′-OH-Δ⁹-THC. The S-isomer was found to be considerably more potent than the R-isomer in producing hypoactivity in mice, static-ataxia in dogs, and in generalization testing in rats trained to discriminate Δ⁹-THC from vehicle. S-3′-OH-Δ⁹-THC was more active than Δ⁹-THC in these tests which means that Δ⁹-THC may be either activated or inactivated in vivo depending upon which metabolite is formed. The difference in potency of these isomers suggests that the conformation of the side chain is critical for behavioral activity. The R and S isomers were found to be equally active in producing hypothermia in mice which is in contrast to the behavioral effects.     

Antagonism of amphetamine locomotor stimulation in rats by single doses of marijuana extract administered orally

The influence of marijuana extract distillate on (+)-amphetamine stimulation of locomotor activity was examined in rats. Marijuana was administered orally and amphetamine was injected intraperitoneally. In rats acclimated to the activity cages, doses of the extract of 5, 10, and 20 mg/kg Δ⁹-THC administered one hour before amphetamine resulted in a significant antagonism of the locomotor stimulation induced by 1 mg/kg (+)-amphetamine; doses of 0·625, 1·25 and 2·5 mg/kg Δ⁹-THC had no effect on the amphetamine response. A dose of 10 mg/kg Δ⁹-THC (as the extract) antagonized the stimulation produced by 0·5,1 and 2 mg/kg (+)-amphetamine in acclimated animals without depressing baseline activity; however, the same dose of marijuana failed to alter significantly the stimulant effect of 1 mg/kg (+)-amphetamine in nonacclimated rats. Although pretreatment with marijuana extract 1 hr before injection of amphetamine resulted in a marked depression of the amphetamine response, when both drugs were administered at the same time only a small and non-significant decrement in the amphetamine response was observed. In conclusion, this study clearly demonstrates that orally administered marijuana antagonizes amphetamine-induced locomotor stimulation in the rat. Mo evidence of enhancement of the amphetamine effect was observed.     

Interactions of several cannabinoids with the hepatic drug metabolizing system

Spectral interactions of various cannabinoids with rat liver musomes and their effects on several musomal enzymes were studied. Δ⁹-Tetrahydrocannabinol (Δ⁹-THC), Δ⁸-tetrahydrocannabinol (Δ⁸-THC), cannabinol (CBN), and cannabidiol (CBD) produced type I spectral changes; the spectral dissociation constants K_s were 42, 37, 46 and 11·2 μM, respectively,. Aminopyrine demethylation was competitively inhibited by Δ⁸-THC, Δ⁸-THC, CBN and CBD, by the latter only in concentrations below 10 μM. The inhibitor constants were found to be 58, 60, 68 and 49 μM, respectively. In a similar way morphine demethylation was inhibited. Δ⁸-THC, however, did not inhibit this reaction, and inhibition by CBD was of mixed type at all concentrations. There was no effect of cannabinoids on aniline hydroxylation. The inhibitory potencies of cannabis constituents on drug metabolism in vitro parallel the in vivo results obtained by interaction studies with hexobarbitone. It must be concluded that CBD, which is by far more potent in inhibiting drug metabolism than other cannabinoids, contributes significantly to the effects of crude cannabis preparations at least in rodents.     

Influence of several anesthetic agents on the effects of Δ9-tetrahydrocannabinol on the heart rate and blood pressure of the mongrel dog

Δ⁹-Tetrahydrocannabinol (Δ⁹-THC) 1 mg/kg, i.v. produced a slight but significant reduction in the heart rate of conscious mongrel dogs, and these effects were greatly potentiated by pentobarbital and/or urethane anesthesia. However, significant increase in the heart rate was noted following Δ⁹-THC administration in the dogs anesthetized with a combination of morphine plus chloralose; further, neither morphine nor chloralose alone could reverse the bradycardic effects of Δ⁹-THC. Tachycardia induced by Δ⁹-THC in these dogs could be reversed by bilateral vagotomy or by pretreatment of the animals with methylatropine, or propranolol and/or practolol. The data indicated a complex interaction between Δ⁹-THC and morphine-chloralose combination and the tachycardia induced by Δ⁹-THC under this anesthesia may be due to release of epinephrine by a reflexogenic mechanism involving afferent vagi. Further, while the bradycardic effects of Δ⁹-THC were essentially identical under pentobarbital or urethane anesthesia, the hypotensive effects were similar in urethane or chloralose anesthetized dogs. The study emphasizes that anesthetic interaction should be taken into consideration while investigating mechanisms of actions of pharmacological agents.     

Effects of Δ9-tetrahydrocannabinol in individuals with a familial vulnerability to alcoholism

Background and aims

A family history (FH) of alcoholism accounts for approximately 50 % of the risk of developing alcohol problems. Several lines of preclinical evidence suggest that brain cannabinoid receptor (CB₁R) function may mediate the effects of alcohol and risk for developing alcoholism including the observations that reduced CB₁R function decreases alcohol-related behaviors and enhanced CB₁R function increases them. In this first human study, we probed CB₁R function in individuals vulnerable to alcoholism with the exogenous cannabinoid Δ⁹-tetrahydrocannabinol (Δ⁹-THC).

Design, setting, and participants

Healthy volunteers (n?=?30) participated in a three test day study during which they received 0.018 and 0.036 mg/kg of Δ⁹-THC, or placebo intravenously in a randomized, counterbalanced order under double-blind conditions.

Measurements

Primary outcome measures were subjective “high,” perceptual alterations, and memory impairment. Secondary outcome measures consisted of stimulatory and depressant subjective effects, attention, spatial memory, executive function, Δ⁹-THC and 11-hydroxy-THC blood levels, and other subjective effects. FH was calculated using the Family Pattern Density method and was used as a continuous variable.

Findings

Greater FH was correlated with greater “high” and perceptual alterations induced by Δ⁹-THC. This enhanced sensitivity with increasing FH was specific to Δ⁹-THC’s rewarding effects and persisted even when FH was calculated using an alternate method.

Conclusions

Enhanced sensitivity to the rewarding effects of Δ⁹-THC in high-FH volunteers suggests that alterations in CB₁R function might contribute to alcohol misuse vulnerability.     

The effect of (minus)-delta 9-trans-tetrahydrocannibinol on myocardial contractility and venous return in anesthetized dogs

Administration of (?)-Δ⁹-trans-tetrahydrocannabinol (Δ⁹-THC, 2.5 mg/kg i.v.) to pentobarbital-anesthetized dogs in which heart rate was maintained constant by electrical pacing, decreased aortic blood pressure, cardiac output, left ventricular peak pressure and left ventricular end diastolic pressure and dP/dt. However, the contractility index (max. dP/dt)/I.P. was not altered by the compound. Furthermore, it was shown that the decrease in cardiac output due to Δ⁹-THC could be restored to original levels by an infusion of saline-dextran in quantities sufficient to elevate the left ventricular end diastolic pressure to pre-Δ⁹-THC level.In dogs in which cardiac output was maintained constant by a right heart bypass procedure Δ⁹-THC decreased blood pressure and total peripheral resistance and augmented intravascular blood volume. This increase in intravascular blood volume was significantly less (74%) in animals in which the splanchnic (superior, inferior and celiac) arteries were ligated prior to the administration of Δ⁹-THC. On the other hand, in spinal dogs Δ⁹-THC was devoid of any measurable cardiovascular effects.These observations clearly support the hypothesis that the diminution of cardiac output induced by Δ⁹-THC in animals with constant cardiac rate is primarily due to diminished venous return to the heart and not to an impaired ability of the myocardium.     

Effects of Δ9-THC and a water soluble ester of Δ9-THC on schedule-controlled behavior

Δ⁹-Tetrahydrocannabinol (Δ⁹-THC) and one of its water soluble esters (SP-111) decreased the rates of responding by pigeons working under a variable interval 3-min schedule of food presentation, or a multiple fixed-ratio 30, fixed-interval 5-min schedule of food presentation. Δ⁹-THC was 3–6 times more potent than SP-111 and had a faster onsetof effects on behavior.     

The effect of Δ-tetrahydrocannabinol on the uptake and release of C-dopamine from crude striatal synaptosomal preparations

Δ⁹-Tetrahydrocannabinol (Δ⁹-THC) and a water soluble ester derivative (compound I) caused a concentration-related decrease in the uptake of ¹⁴C-dopamine into crude synaptosomal preparations derived from mouse striata. Both were less potent than amphetamine in this preparation. In the presence of 10^?7m amphetamine the IC₅₀ of Δ⁹-THC was unaffected. The IC₅₀ is the concentration of drug in the medium which will inhibit the uptake of ¹⁴C-dopamine into the synaptosomes by 50%. However in the presence of 3.0 × 10^?6m Δ⁹-THC, the dose response curve to amphetamine was shifted to the right and the IC₅₀ of amphetamine was increased. Δ⁹-Tetrahydrocannabinol and compound I increased the release of ¹⁴C-dopamine from preparations pre-incubated with ¹⁴C-dopamine. The effect was small but significant. The effects of amphetamine and Δ⁹THC combined were additive on this system. The mode of action of Δ⁹-THC with regard to the dopaminergic system of the striatum is discussed.     

THE EFFECT OF δ9-TETRAHYDROCANNABINOL (δ9-THC) ON THE TURNOVER RATE OF BRAIN SEROTONIN OF THE RAT

1. One isotopic and three non-isotopic methods were used to determine the effect of an acute intravenous dose of Δ⁹-tetrahydrocannabinol (Δ⁹-THC, 2 mg/kg) on the rat brain turnover rate of serotonin. 2. In control animals the turnover rate of serotonin was about 2 nmol/g per h. This rate was not altered by Δ⁹-THC when it was calculated from the rise of 5-hydroxyindoleacetic acid following probenecid or from the rise of serotonin following pargyline. 3. Δ⁹-THC did not alter the serotonin turnover rate when it was calculated from the conversion of ³H-tryptophan to ³H-serotonin. 4. The serotonin turnover rate was significantly increased by Δ⁹-THC when the rate was calculated from the decline of 5-hydroxyindoleacetic acid following pargyline. 5. These results suggest that Δ⁹-THC does not alter the turnover of rat brain serotonin. The previously reported Δ⁹-THC-induced changes in body temperature and increased brain levels of 5-hydroxyindoleacetic acid may be mediated by some other mechanism such as interference by Δ⁹-THC of the vesicular binding of serotonin.