Changes induced by hashish constituents on human erythrocyte phospholipids

The possible effect of delta 9-THC on human erythrocyte phospholipids of chronic hashish users was studied. Changes in individual phospholipids concentrations were observed in heavy hashish users after smoking the drug. Results are discussed in relation to the possible alterations of enzymatic mechanisms which require the presence of essential for their activation phospholipids.     

Effects of chronic administration of delta 9-transtetrahydrocannabinol (delta9-THC) in guinea-pigs.

The guinea-pigs were divided into three groups: (1) absolute control, (2) solvent control (tween 4%), and (3) delta9-THC group (3 mg/kg). The selected dose of delta9-THC corresponds to the minim amount producing physiological effects in acute administration and was given for six months at the rate of five injections/week. The results showed that THC produced no changes on these parameters: serum glucose, urea nitrogen, total proteins, Mg, Ca, Na, and K. However, the fatty acids and alpha1 globulin were significantly decreased. There was a significant increase in gamma globulin. The body weight gain of delta9-THC treated animals was lower than of the two controls. Delta9-THC decreased the relative weight of liver and spleen; however, it did not significantly affect the relative weight of heart, adrenals, and kidneys. Similarly, the morphological examinations showed no alteration in these tissues, except in the liver tissue, where a perturbation of the autodigestion of glycogen was noted. These observations suggest that the toxic effect of the drug is caused by its accumulation in the liver, which provokes an inhibition of certain liver enzymatic systems.     

Effects of long-term administration and withdrawal of tetrahydrocannabinols (delta 8-THC and delta 9-THC) on open-field behavior in rats

The behavior of female Wistar rats, injected daily with Δ⁸-THC (5.0 mg/kg), Δ⁹-THC (2.5 mg/kg) or vehicle was studied in an open-field test both during the two weeks' period of drug administration and after withdrawal. The behavior of rats allowed long-term acclimation to the laboratory (LTA), studied in Experiment 1, was compared with those of Experiment 2, which were subjected to short-term acclimation (STA). Throughout the injection period a depressant effect of both isomers of THC was seen on ambulation, rearing, grooming and latency. Length of acclimation period interacted with the effects of THC:s on ambulation, producing even an increased ambulation for Δ⁸-THC in the STA group. Minor indications of tolerance to Δ⁹-THC were observed in the LTA condition only. A kind of circling behavior was characteristic of both drug groups, its frequency declining with repeated injections. At drug withdrawal, most open-field measures slowly returned to control levels, whereas rate of grooming showed a manifold increase. Possible implications of the results for behavioral research with the THC:s are discussed.     

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.     

Effects of delta 9-THC and castration on behavior and plasma hormone levels in male mice

Gonadectomy resulted in a rapid increase in plasma luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels, but had no consistent effects on plasma prolactin (PRL) and growth hormone (GH) levels. In castrated males, oral administration of THC (50 mg/kg) significantly increased plasma LH levels within hours following surgery and again from 3 to several weeks post-castration, while THC treatment decreased LH levels between 1 day and 2 weeks postcastration. Administration of THC to 12-hour sham castrates significantly increased plasma LH levels. Plasma FSH, PRL and GH levels were either reduced or unchanged by THC. Administration of THC significantly reduced levels of gonadotropins, PRL and GH in intact males. In additional studies, we examined the influence of THC on the negative feedback response of the anterior pituitary to gonadal steroids. In testosterone propionate (TP)-treated castrated males, concomitant administration of THC increased plasma testosterone (T) and LH at 20 min, while plasma FSH levels were elevated after 60 min. In contrast, in intact TP-treated mice, concomitant THC exposure reduced plasma T levels except at 60 min, when plasma LH levels were significantly increased. Testosterone replacement failed to restore copulatory behavior in castrated mice given a single dose (50 mg/kg) of THC. In fact, acute THC administration to these TP-treated castrates resulted in marked sedation, which was not observed in intact mice given the same dose of THC in an earlier study. The present findings indicate that the effects of acute THC treatment on pituitary gonadotropin release is dependent upon the time after castration. Furthermore, THC administration can suppress copulatory behavior even in animals whose peripheral T levels have been maintained. Effects of THC on plasma androgen levels in animals injected with TP suggest that THC can alter the metabolism or target tissue response to gonadal steroids.     

Effects of acute delta 9-THC administration on EEG and EEG power spectra in the rat

This study was designed to determine the acute effects of delta 9-THC on the cortical EEG with the spectral analysis technique. Adult female Sprague-Dawley rats were implanted with chronic cortical and temporalis muscle electrodes. Intraperitoneally administered delta 9-THC (5 and 10 mg/kg) produced a reduction in peak-to-peak voltage of the desynchronized cortical EEG during wakefulness. Associated spectral power was reduced to about 50% of control during the first hour after injection of delta 9-THC and gradually returned toward the control value over an 8-hr period. Occurrences of delta 9-THC-induced high-voltage EEG bursts, overriding the reduced EEG tracing, were associated with an EEG spectral peak at 6 Hz. The first few slow-wave sleep (SWS) episodes appearing after delta 9-THC administration were associated with more slow-frequency waveforms and more slow-frequency spectral power than with control slow-wave sleep episodes. During control rapid eye movement (REM) sleep episodes, an EEG theta wave pattern, with an associated spectral peak at about 8 Hz, was characteristic. Conversely, the first few REM sleep episodes emerging after delta 9-THC administration contained overriding high-voltage bursts, the related power spectra of which had two peaks at about 7 and 11 Hz.     

Parameters influencing the effect of delta9-THC on activity wheel behavior

In 2 studies the effect of Δ⁹-THC on activity wheel behavior in rats was examined. The amount of laboratory acclimation prior to testing was manipulated and either 4 mg/kg or 8 mg/kg Δ⁹-THC was given intraperitoneally. Activity counts were taken 15 minutes, 1, 6, 24, 48 or 72 hr after the injection. Those animals that received 4 mg/kg Δ⁹-THC and had little laboratory acclimation were significantly more active than their controls during the first 15 min but, after 1 hr were, like the other 3 experimental groups, less active than the appropriate controls. The time course for the depressant action of the Δ⁹-THC at both dose levels was quite similar and lasted for approximately 24 hr.     

Influence of tetrahydrocannabinols (delta8-THC and delta9-THC) on body weight, food, and water intake in rats

Female Wistar rats, six to a group, were injected daily for a 23-day period with Δ⁸-THC (5.0 mg/kg), Δ⁹-THC (2.5 mg/kg) or vehicle. Body weight, food and water intake were recorded every second day. It was found that Δ⁸-THC caused a decrease of body weight, to a level maintained throughout the injection period, with only slight signs of recovery. Both drugs caused a marked decrease of water intake. Food intake was not significantly affected by the drugs. Factors in relation to the effects of THC on body weight, food and water intake are discussed.     

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.     

Changes of HDL-lipid composition as related to delta 9-THC action

An attempt was made to investigate the possible action of delta 9-THC on HDL-Lipid composition. Significant changes were observed in the serum total lipids, triglycerides and HDL subfractions after hashish smoking. The results are discussed in relation to the possible alterations of some enzymatic mechanisms regulating lipid metabolism in hashish users.     

Differential effects of delta9-THC on learning in adolescent and adult rats

Marijuana use remains strikingly high among young users in the U.S., and yet few studies have assessed the effects of delta9-tetrahydrocannabinol (THC) in adolescents compared to adults. This study measured the effects of THC on male adolescent and adult rats in the Morris water maze. In Experiment 1, adolescent (PD=30-32) and adult (PD=65-70) rats were treated acutely with 5.0 mg/kg THC or vehicle while trained on the spatial version of the water maze on five consecutive days. In Experiment 2, adolescent and adult rats were treated acutely with 2.5 or 10.0 mg/kg THC or vehicle while trained on either the spatial and non-spatial versions of the water maze. In Experiment 3, adolescent and adult rats were treated with 5.0 mg/kg THC or vehicle daily for 21 days, and were trained on the spatial and then the non-spatial versions of the water maze task four weeks later in the absence of THC. THC impaired both spatial and nonspatial learning more in adolescents than in adults at all doses tested. However, there were no long-lasting significant effects on either spatial or non-spatial learning in rats that had been previously exposed to THC for 21 days. This developmental sensitivity is analogous to the effects of ethanol, another commonly used recreational drug.     

Determination of delta9-THC in whole blood using gas chromatography-mass spectrometry

A simple and reliable liquid-liquid extraction method for the determination of delta9-tetrahydrocannabinol (THC) in whole blood utilizing gas chromatography-mass spectrometry in electron impact mode is described. The substance is derivatized with pentafluoropropionic anhydride in pentafluropropanol. The limit of detection is 0.5 ng/mL for a 1-mL specimen, with recovery greater than 70%. The intra-assay coefficient of variation (CV) is 3.1% to 5.2%, and the interassay CV is 6.4% to 9.5%, calculated at THC concentrations of 1, 5, and 25 ng/mL. The accuracy is between 95 and 97%. The optimization of extraction and derivatization conditions is detailed.     

Differential effects of delta 9-THC on spatial reference and working memory in mice

RATIONALE: Marijuana remains the most widely used illicit drug in the U.S., and recent attention has been given to putative therapeutic uses of marijuana and cannabinoid derivatives. Thus, developing a better understanding of delta9-THC (tetrahydrocannabinol)-induced mnemonic deficits is of critical importance. OBJECTIVES: These experiments were conducted to determine whether delta9-THC has differential effects on spatial reference and working memory tasks, to investigate its receptor mechanism of action, and to compare these effects with those produced by two other compounds--scopolamine and phencyclidine--known to produce mnemonic deficits. In addition, the potency of delta9-THC in these memory tasks was compared with its potency in other pharmacological effects traditionally associated with cannabinoid activity. METHODS: Two different versions of the Morris water maze were employed: a working memory task and a reference memory task. Other effects of delta9-THC were assessed using standard tests of hypomotility, antinociception, catalepsy, and hypothermia. RESULTS: delta9-THC disrupted performance of the working memory task (3.0 mg/kg) at doses lower than those required to disrupt performance of the reference memory task (100 mg/kg), or elicit hypomotility, antinociception, catalepsy, and hypothermia. These performance deficits were reversed by SR 141716A. The effects of delta9-THC resembled those of scopolamine, which also selectively disrupted the working maze task. Conversely, phencyclidine disrupted both tasks only at a dose that also produced motor deficits. CONCLUSIONS: These data indicate that delta9-THC selectively impairs performance of a working memory task through a CB, receptor mechanism of action and that these memory disruptions are more sensitive than other pharmacological effects of delta9-THC.     

A novel female influences delta 9-THC effects on plasma hormone levels in male mice

Exposure to delta 9-tetrahydrocannabinol (THC) (50 mg/kg) alters the endocrine responsivity of male mice to female-related exteroceptive stimuli. Exposure to a novel female prevents or delays the THC-induced decrease in plasma testosterone (T) and luteinizing hormone (LH) levels. These hormonal alterations are apparently not due to the LH-releasing effects of female-related pheromonal or tactile cues, since administration of luteinizing hormone releasing factor (LRF) did not mimic the effects of a novel female on plasma T levels in THC-treated males. Exposure to a much lower dose of THC (0.5 mg/kg) did augment the LRF-induced increases in plasma T levels suggesting a possible synergism between gonadotropins and THC on androgen production. The present findings suggest that THC-induced alterations in hormonal status may be influenced by complex social or environmental factors.     

Maternal responsiveness in the squirrel monkey following chronic administration of delta 9-THC.

Mother squirrel monkeys were orally administered gradually increasing doses of delta 9-THC (from 0.5 to 5.0 mg/kg) 5 days/wk from 2 wk to approximately 6 mo after birth. After having received a dose of 5.0 mg/kg for an average of 3.5 mo, drug-treated mothers were then compared with control mothers in terms of theri responsiveness both to their own and to unrelated infants. In contrast to the control mothers whose response pattern clearly showed differentiation of their own and other infants, the mothers that received delta 9-THC responded in much the same manner to the alien infant as they did to their own infant. The results show that the behavior of the THC-exposed mothers was not attributed simply to a general reduction in their responsiveness toward their offspring or to an overall reduction in their own state of arousal. Rather, the results suggest that chronic ingestion of delta 9-THC caused the mothers to be less disturbed by separation from their infants and/or produced degree of perceptual distortion that prevented them from responding selectively to the different infants.     

Effects of chronic delta-9-THC treatment on cardiac beta-adrenoceptors in rats

This study was designed to determine if chronic treatment with delta-9-tetrahydrocannabinol (THC) alters cardiac beta-adrenoceptors in the rat. Following daily oral administration of 10 or 20 mg/kg THC or an equivalent volume of control solvent for 90 days, rats were sacrificed, and sarcolemmal membranes were prepared from ventricular myocardium. Beta-adrenoceptor density and binding affinity estimated with (-)[3H]dihydroalprenolol; a beta-adrenergic antagonist, were not significantly affected by treatment with THC when compared to vehicle controls. These results suggest that the tolerance to cardiovascular effects of THC which develops during chronic exposure in the rat is not associated with alterations in cardiac beta-adrenoceptors as monitored by radiolabeled antagonist binding.     

Treatment of Tourette syndrome with delta-9-tetrahydrocannabinol (delta 9-THC): no influence on neuropsychological performance.

Previous studies provide evidence that marijuana (Cannabis sativa) and delta-9-tetrahydrocannabinol (Delta(9)-THC), the major psychoactive ingredient of marijuana, respectively, are effective in the treatment of tics and behavioral problems in Tourette syndrome (TS). It, therefore, has been speculated that the central cannabinoid receptor system might be involved in TS pathology. However, in healthy marijuana users there is an ongoing debate as to whether the use of cannabis causes acute and/or long-term cognitive deficits. In this randomized double-blind placebo-controlled study, we investigated the effect of a treatment with up to 10 mg Delta(9)-THC over a 6-week period on neuropsychological performance in 24 patients suffering from TS. During medication and immediately as well as 5-6 weeks after withdrawal of Delta(9)-THC treatment, no detrimental effect was seen on learning curve, interference, recall and recognition of word lists, immediate visual memory span, and divided attention. Measuring immediate verbal memory span, we even found a trend towards a significant improvement during and after treatment. Results from this study corroborate previous data suggesting that in patients suffering from TS, treatment with Delta(9)-THC causes neither acute nor long-term cognitive deficits. Larger and longer-duration controlled studies are recommended to provide more information on the adverse effect profile of THC in patients suffering from TS.     

Comparison of the discriminative stimulus properties of delta9-THC and psilocybin in rats.

Male albino rats were trained to respond differentially on the left or right lever in a 2-lever chamber on the basis of which drug had been given intra-peritoneally (IP) 30 min before experimentation. In 1 group 1.9 mg/kg of delta9-THC and control injections (vehicle) served as the discriminative stimuli associated with each lever and in another group the drug stimuli were 1.0 mg/kg of delta9-THC and 1.0 mg/kg of psilocybin. The results confirmed those of other experiments using different procedures; that delta9-THC can acquire discriminative control over responding. The fact that delta9-THC and psilocybin were also found to differentially control lever choice demonstrates that these 2 drugs probably produce discriminably different states in rats.     

SR 141716A differentially attenuates the behavioral effects of delta9-THC in rhesus monkeys

The prototypic cannabinoid CB1 antagonist SR 141716A is one important pharmacologic tool for examining CB1 receptors that mediate the behavioral and physiologic effects of delta9-tetrahydrocannabinol (delta9-THC). This study examined the effects of SR 141716A on the rate-decreasing, hypothermic and discriminative stimulus effects of delta9-THC in rhesus monkeys. In monkeys (n=4) responding under a multiple fixed ratio (FR-10:FR-10) schedule of food presentation and stimulus-shock termination, the potency of i.m. delta9-THC to decrease responding in the food component (ED50=0.64 mg/kg) was threefold greater than its potency in the stimulus-shock termination component (ED50=2.14 mg/kg). In the same monkeys, hypothermia was induced by delta9-THC at a dose (e.g. 0.32 mg/kg) that did not alter responding in either schedule component; the maximum decrease was 2.1 degrees C at a dose of 3.2 mg/kg. A dose of 0.32 mg/kg of SR 141716A, significantly attenuated delta9-THC-induced hypothermia without attenuating the rate-decreasing effects of delta9-THC in either component of the multiple schedule. The largest dose of i.m. SR 141716A that was studied, 1.0 mg/kg, significantly decreased rectal temperature and responding in the food component but did not significantly decrease responding in the stimulus-shock termination component of the multiple schedule. In a separate group of monkeys (n=3) that discriminated i.v. delta9-THC (0.1 mg/kg) while responding under an FR-5 schedule of stimulus-shock termination, SR 141716A (0.32 and 1 mg/kg) significantly increased the ED50 of the delta9-THC by 2.3- and 3.7-fold, respectively. Collectively, these results demonstrate that the behavioral effects of delta9-THC are not equally attenuated by SR 141716A.     

Reversal of delta 9-THC hyperphagia by SR141716 and naloxone but not dexfenfluramine.

Presatiated adult male Lister hooded rats received oral administration of the exogenous cannabinoid Delta-9-tetrahydrocannabinol (Delta(9)-THC; 1.0 mg/kg) in combination with subcutaneous injection of either the cannabinoid CB1 antagonist N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methylpyrazole-3-carboxamide (SR141716; 0, 0.05, 0.1, 0.5 or 1.0 mg/kg), the CB2 antagonist N-[(1S)-endo-1,3,3-trimethyl bicyclo[2.2.1]heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-pyrazole-3-carboxamide (SR144528; 0, 0.05, 0.1, 0.5 or 1.0 mg/kg), the general opioid antagonist naloxone (0.1, 0.5, 1.0 or 5.0 mg/kg) or the 5-HT agonist dexfenfluramine (0.05, 0.1, 0.5, 1.0 or 5.0 mg/kg). Food (chow) intake was measured over 2 h from the onset of the dark period. Delta(9)-THC induced significant hyperphagia, which was attenuated by subanorectic doses of SR141716 and naloxone. Neither SR144528 nor dexfenfluramine affected Delta(9)-THC-induced feeding. These data confirm mediation of Delta(9)-THC hyperphagia by central-type CB1 receptors, and support a functional relationship between cannabinoid and opioid systems in relation to appetite regulation. Stimulation of CB1 receptors may promote feeding by actions on food reward rather than by inhibition of serotonergic satiety mechanisms.