Pre- and postganglionic stimulation-induced noradrenaline overflow is markedly facilitated by a prejunctional β2-adrenoceptor-mediated control mechanism in the pithed rat

The aim of the study was to further explore the prejunctional -adrenoceptor-mediated control mechanism of noradrenaline release from sympathetic nerves in response to preganglionic nerve stimulation (PNS) and local nerve stimulation of the portal vein, respectively, in the pithed rat.Baseline values as well as the increments of mean arterial blood pressure (-BP), heart rate (-HR) and plasma noradrenaline levels (-NA) in response to four PNS episodes (0.8 Hz, 3 ms, 75 V for 45 s at 20 min intervals), respectively, were evaluated. Fenoterol administration (0.25 mg/kg, i.v.) reduced significantly the basal blood pressure but did not alter d-BP in response to PNS. Basal heart rate markedly increased after fenoterol without any further change in heart rate induced by PNS.The ₁-selective antagonist CGP 20712A attenuated -BP in response to PNS and prevented the fenoterol-induced increase in basal heart rate. The ₂-selective antagonist ICI 118,551 per se did not change the blood pressure and heart rate values, but antagonized the fenoterol-induced decrease in basal blood pressure.Fenoterol enhanced plasma -NA in response to PNS by 105% in comparison to the corresponding control value. This effect of fenoterol could be blocked by pretreatment with ICI 118,551 but not with CGP 20712A (a selective ₁-adrenoceptor antagonist) which per se did not significantly change plasma -NA.Repeated local stimulation of the portal vein (S1–S 3, 2 Hz, 3 ms, 10 mA, for 120 s at 30 min intervals) increased portal plasma noradrenaline without changing mean blood pressure and heart rate in pithed rats. Fenoterol enhanced the increase in portal-vein plasma noradrenaline evoked by nerve stimulation by 110%. Pretreatment with ICI 118,551 antagonized this effect of fenoterol, but had per se no effect on the portal vein nerve stimulation-evoked increase in portal plasma noradrenaline.It is concluded that the increase in plasma noradrenaline evoked both by pre- and postganglionic nerve stimulation can be markedly enhanced by activation of a facilitatory prejunctional ₂-adrenoceptor control mechanism. Correspondence to: V.I. Tarizzo     

Clinical effects and plasma levels of Δ9-Tetrahydrocannabinol (Δ9-THC) in heavy and light users of cannabis

⁹-Tetrahydrocannabinol (⁹-THC) was administered in a crossover design by smoking and IV injection to groups of heavy and light users of marihuana. Plasma concentrations of ⁹-THC were similar for the groups after IV injection of 5.0 mg ⁹-THC, but the AUC_{0–240 min} showed a trend towards lower values for the heavy user group. To achieve a maximum desired high, both groups smoked similar amounts (about 13 mg) of ⁹-THC. Heavy users tended to have higher plasma levels than light users. The systemic availability of smoked ⁹-THC was significantly higher for the heavy users (heavy users 23±16% vs 10±7% for light users). These results also indicate that heavy cannabis users smoke more efficiently than casual smokers.Both light and heavy users showed more clinical effect following IV administration than after smoking. The response of the heavy users, both with respect to effect on heart and high, was quite comparable to that of light users.The present study does not suggest that tolerance readily develops in heavy users.     

Lack of cross-tolerance in rats among (−) Δ9-trans-tetrahydrocannabinol (Δ9-THC), cannabis extract,mescaline and lysergic acid diethylamide (LSD-25)

Summary Using climbing rope and bar-pressing behavior methods, rats were rendered tolerant to ⁹-THC, cannabis extract, mescaline and LSD-25. Cross-tolerance experiments showed that rats refractory to ⁹-THC and cannabis extract were still sensitive to mescaline and LSD-25, and vice-versa.These results suggest that, in spite of the similarity of the clinical symptoms produced in man by the 3 drugs, ⁹-THC may have its psychotomimetic effects produced by different mechanisms from those of LSD-25 and mescaline.This work was partially supported by a grant from Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP).     

Effects of 2-propyl 2-pentenoic acid on the acquisition of conditioned behavior with negative reinforcement in mice

2-Propyl 2-pentenoic acid (PP), at a dose of 6 mg/kg (0.04 mM/kg), has a facilitating action on the acquisition of conditioned avoidance reactions. This effect of PP is correlated with increase of the level of brain gamma-aminobutyric acid, following administration of PP.     

Cannabis interferes with nest-building behavior in mice

Nest-building, a behavioral model shown to be disrupted by hallucinogens, has never been used to answer questions concerning the psychotomimetic effects of ⁹-THC. Several fractions of cannabis and tobacco pyrolysis products were tested consecutively in the same procedure. The following drugs were injected i.p. under a saline-drug-saline schedule: d-amphetamine (6 mg/kg), pentobarbital (25 mg/kg), ⁹-THC (10 mg/kg, 5 mg/kg, 2.5 mg/kg), the cannabis fractions designated I_s (water soluble products), II_s (nonsoluble, nonvolatile products), III_s (it comprises what is inhaled by a common hashish smoker), and analogous fractions of tobacco pyrolysis products designated III_B (what is inhaled by a common tobacco smoker), II_B and I_B.The effects of ⁹-THC (10 mg/kg), II_s, and III_s were quite similar as far as the disruption of the normal behavioral pattern is concerned. d-Amphetamine, ⁹-THC (5 mg/kg), and II_B disrupted the normal behavioral pattern as well. The similarity of the effects of II_s and III_s was unexpected in view of the different contents of cannabinoids in these fractions. Also unexpected was the similarity of the effects of ⁹-THC (10 mg/kg) and III_s (40 mg/kg containing 7% ⁹-THC) as well as the activity of fraction III_B.     

Hashish extract impairs retention of defeat-induced submissive behavior in mice

The effects of hashish extract on adaptive behavior of male mice were studied in a paradigm which allows the investigation of learning mechanisms in a social context. Mice of the C3H strain, which were not submissive in a confrontation with a nonaggressive DBA mouse on day 1, were defeated on day 2 over 3 min by aggressive, isolated DBA mice, and showed conditioned submissive behavior upon mere contact with a nonaggressive DBA mouse on day 3. A hashish extract containing 38.6–39.4% ⁹-tetrahydrocannabinol ( ⁹-THC), 11.6–12.0% cannabinol and 47.7–48.5% cannabidiol was administered orally in all experiments. Hashish extract given 90 min before defeat on day 2, in dosages corresponding to 1, 5, and 10 mg ⁹-THC/kg, impaired retention of defensive upright, defensive sideways and immobility on day 3 (experiment 1). Experiment 2 showed that the drug (5, and 10 mg ⁹-THC/kg) had no antinociceptive potency in mice and did not modify defeat-induced analgesia. Experiment 3, with drug (5 mg ⁹-THC/kg) or solvent administration on day 2 and day 3, showed that the retention deficit was neither due to state-dependent learning, nor to impaired retrieval. It is suggested that hashish extract administered before learning may interfere with memory processing.     

Effects of chronic Δ9-tetrahyrocannabinol administration on schedule-controlled behavior of pigeons: Cross-tolerance to pentobarbital and barbital

Pigeons responding under a variable-interval (VI) 75-s schedule of food presentation were used to study cross-tolerance from ⁹-tetrahyrocannabinol (⁹-THC) to pentobarbital and barbital. After initial dose-effect functions for pentobarbital and barbital were determined, the birds received ⁹-THC injections for 6 weeks. This chronic administration regimen resulted in a greater than 100-fold tolerance to ⁹-THC. Redetermination of the pentobarbital and barbital dose-effect functions during the chronic ⁹-THC regimen revealed statistically significant shifts to the right for the pentobarbital (0.191 log unit) and barbital (0.078 log unit) dose-effect curves. All six birds showed tolerance to pentobarbital, while four of the six showed tolerance to barbital. Blood barbital levels before and after chronic ⁹-THC administration did not differ significantly. Tolerance to ⁹-THC was more prolonged and of much greater magnitude than the cross-tolerance to pentobarbital or barbital. The results demonstrate that cross-tolerance can develop from ⁹-THC to a barbiturate that normally undergoes little metabolism.     

Effect of cannabinoids on the turnover rate of acetylcholine in rat hippocampus,striatum and cortex

Summary The effects of ⁹-tetrahydrocannabinol, (⁹THC) the major psychoactive compound of marijuana, and cannabidiol (CBD), a non-psychoactive component, on the acetylcholine (ACh) concentration and the turnover rate of ACh (TR_ACh) have been studied in various regions of the rat brain. Neither ⁹THC doses from 0.2 to 10 mg/kg nor CBD (10 or 20 mg/kg) alter the ACh concentration in the brain areas examined 30 min, after the intravenous injection. However, ⁹-THC (doses from 0.2 to 10 mg/kg) causes a marked dose-related decrease in the TR_ACh in hippocampus whereas CBD is without effect in this brain region even when 20 mg/kg is given. Furthermore, high doses of ⁹-THC (5 mg/kg) and CBD (20 mg/kg) that produce a significant decrease in the TR_ACh of striatum fail to change the TR_ACh in parietal cortex. The low doses of ⁹-THC required to reduce hippocampal TR_ACh suggest that an action on these cholinergic mechanisms may play a role in the psychotomimetic activity of ⁹-THC.     

Immobilized Artificial Membrane (lAM)-HPLC for Partition Studies of Neutral and Ionized Acids and Bases in Comparison with the Liposomal Partition System

Purpose. To study the partitioning of model acids ((RS)-warfarin and salicylic acid), and bases (lidocaine, (RS)-propranolol and diazepam), with immobilized artificial membrane (lAM)-HPLC, as compared to partitioning in the standardized phosphatidylcholine liposome/buffer system. Methods. The pH-dependent apparent partition coefficients D were calculated from capacity factors (k_IAM) obtained by IAM-HPLC, using a 11-carboxylundecylphosphocholine column. For lipophilic compounds k_IAM, values were determined with organic modifiers and extrapolation to 100% water phase (k_IAMw) was optimized. Temperature dependence was explored (23 to 45° C), and Gibbs free energy (G), partial molar enthalpy (H) and change in entropy (S) were calculated. Equilibrium dialysis was used for the partitioning studies with the liposome/buffer system. Results. For extrapolation of k_IAMw, linear plots were obtained both with the respective dielectric constants and the mole fractions of the organic modifier. All tested compounds showed a similar pH-D diagram in both systems; however, significant differences were reproducibly found in the pH range of 5 to 8. In all cases, G and H were negative, whereas S values were negative for acids and positive for bases. Conclusions. In both partitioning systems, D values decreased significantly with the change from the neutral to the charged ionization state of the solute. The differences found under physiological conditions, i.e. around pH 7.4, were attributed to nonspecific interactions of the drug with the silica surface of the IAM column.     

Learning impairment in the radial-arm maze following prolonged cannabis treatment in rats

Chronic oral administration of cannabis extract to rats (daily ⁹tetrahydrocannabinol dose 20 mg/kg) was examined in three experiments for its residual effect on radialarm maze learning following a 1-month drug-free period. Learning a simple eight-arm maze was significantly impaired in rats treated for either 6 months (Experiment I) or 3 months (Experiment II) with the drug. In Experiment III, animals that received the extract for 3 months exhibited significant learning deficits on a much more difficult 12-arm radial maze. The results demonstrate that the deleterious effects of cannabis on radial-arm maze learning are probably due to a tendency toward increased vigilance and perseveration, possibly combined with an impaired utilization of spatial cues.     

The effect of two tetrahydrocannabinols, (Δ9-THC and Δ8-THC) on conditioned avoidance learning in rats and its transfer to normal state conditions

Rats trained in conditioned avoidance responding (CAR) after injections of either 7.5 mg/kg ⁹-THC (tetrahydrocannabinol) or 15 mg/kg ⁸-THC, showed no transfer when tested in the non-drugged state. Furthermore, these doses of the isomeric tetrahydrocannabinols exerted a disruptive effect on previously established CAR in rats, trained under normal conditions.Only the ⁹-THC-group showed an impairment of acquisition which was statistically significant compared to the control group.     

Metabolism and autoradiographic distribution of Δ8- and Δ9 tetrahydrocannabinol in some organs of the monkey callithrix jacchus

Summary Metabolism and autoradiographic distribution of the two isomeric tetrahydrocannabinols, (2,4-¹⁴C)-⁸-THC and (2,4-¹⁴C)-⁹-THC), were studied in the marmoset Callithrix jacchus. Of the two cannabinoids, ⁸-THC had a slower initial rate of biotransformation to the psychopharmacologically more potent 11-hydroxylated metabolite. This may explain the minor psychopharmacological activity of the ⁸-isomer. In glandular tissues an accumulation of unchanged ⁹-THC was observed.Autoradiography revealed characteristic label distributions in some organs 30 min after the administration of the drugs. This labelling pattern was found to be changed after a 6-hr incorporation period. The autoradiographic distribution of ⁸- and ⁹-THC appeared to be identical.     

Effects of acute and chronic administration of cannabis sativa and (−)Δ9-trans-tetrahydrocannabinol on the behavior of rats in an open-field arena

The effects of acute and chronic administration of ⁹-THC, cannabis extract and control solution on the behavior of rats repeatedly exposed to an open-field arena have been studied. After the first dose both ⁹-THC and cannabis extract significantly decreased defecation, grooming and rearing; ambulation was not affected. After 20 injections of both marihuana compounds the rats showed values for defecation, grooming and rearing near to those obtained during the predrug phase; control rats, however, showed a significant decrease in these parameters indicating habituation to the open-field. The results are discussed in terms of effects of marihuana on emotional behavior of rats.This work was partially supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP).With a fellowship iniciação científica from FAPESP.     

Syntheses of di- and tetrahydropyrroles

Conclusions N-Alkyl-2,4,4-trimethyl-'-pyrrolinium salts were produced by alkylating 2,4,4-trimethyl-'-pyrroline with various alkylating agents.For communication IV, see [1].Translated from Khimiko-Farmatsevticheskii Zhurnal, No. 8, pp. 30–34, August, 1968.     

Effect of some cannabinoids on naloxone-precipitated abstinence in morphine-dependent mice

Mice were rendered morphine-dependent by the subcutaneous implantation of a pellet containing 75 mg of morphine base; 72 h after the implantation, the animals were injected intraperitoneally either with vehicle or with various doses of ₉-tetrahydrocannabinol, ₈-tetrahydrocannabinol, cannabidiol, cannabinol, or 11-hydroxy-₈-tetrahydrocannabinol. Thirty minutes after injection of the cannabinoids, the antagonist, naloxone HCl, was administered to induce the stereotyped withdrawal jumping syndrome. The dose of naloxone needed to induce withdrawal jumping in 50% of the animals (ED₅₀) was determined for each dose of the cannabinoids. All of the cannabinoids inhibited the naloxone-precipitated morphine abstinence as evidenced by an increase in the naloxone ED₅₀. Two additional signs of morphine abstinence, defecation and rearing behavior, were also suppressed by the cannabinoids. The relative effectiveness of the cannabinoids in inhibiting morphine abstinence appeared to be in the following order: ₉-tetrahydrocannabinol > ₈-tetrahydrocannabinol > 11-hydroxy-₈-tetrahydrocannabinol > cannabidiol > cannabinol.These data suggest that cannabinoids may be useful in facilitating narcotic detoxification.     

Effect of hexachlorobenzene on enzymes of the steroid metabolism in rat liver

Adult female Wistar rats were fed with a diet containing 0.05% hexachlorobenzene. On the 60th day of this treatment the specific activities of NADPH: ⁴-3-oxosteroid-5-reductase and the 3-hydroxysteroid dehydrogenases in rat liver microsomes were diminished compared to control rats. The cytoplasmatic 5-reduction was higher in HCB treated rats than in control rats. These alterations of the steroid metabolism lead to increased formation of 5-H-steroids which are known to be inducers of the porphyrin biosynthesis.

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Zusammenfassung Erwachsene weibliche Wistar-Ratten wurden mit 0.05% Hexachlorbenzol enthaltendem Futter ernährt. Am 60. Tag dieser Behandlung waren die spezifischen Aktivitäten der NADPH: ⁴-3-oxosteroid-5-Reduktase und der 3-Hydroxysteroid-Dehydrogenasen in Lebermikrosomen, verglichen mit Kontroll-Ratten, vermindert. Die cytoplasmatische 5-Reduktion war bei HCB-behandelten Ratten höher als bei Kontroll-Ratten. Diese Veränderungen des Steroidmetabolismus führen zu vermehrter Bildung von 5-H-Steroiden, von denen bekannt ist, daß sie Induktoren der Porphyrin-Biosynthese sind.

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Abbreviations HCB Hexachlorobenzene - 5-DHT 5-Dihydrotestosterone (17-hydroxy-5-androstan-3-one) - 5-DHT 5-dihydrotestosterone (17-hydroxy-5-androstan-3-one) Dedicated to Prof. Dr. Hj. Staudinger on occasion of his 65th birthday     

Facilitory effect of Δ9-tetrahydrocannabinol on hypothalamically induced feeding

Six male Lewis rats were tested for the effect of ⁹-tetrahydrocannabinol (⁹-THC) on feeding evoked by electrical stimulation of the lateral hypothalamus. Treatment with ⁹-THC (0.4 mg/kg IP) decreased frequency threshold for feeding by 20.5% (±4.3), causing a leftward shift in the function relating stimulation frequency to the latency to begin eating 45-mg food pellets upon stimulation onset; there was no change in the asymptotic performance that was approached with sufficiently high stimulation frequencies. Naloxone (1 and 2 mg/kg) reduced the facilitory effect of ⁹-THC, but did so at doses that can inhibit feeding in the no-drug condition. These data are consistent with evidence implicating endogenous opioids in feeding, and suggest (but do not confirm) that the facilitation of feeding by ⁹-THC may be mediated by endogenous opioids. The facilitation of stimulation-induced feeding by doses of ⁹-THC that have been found to facilitate brain stimulation reward is consistent with evidence suggesting common elements in the brain mechanisms of these two behavioral effects of medial forebrain bundle stimulation.     

Reinforcing properties of oral Δ 9-tetrahydrocannabinol,smoked marijuana,and nabilone: Influence of previous marijuana use

The reinforcing properties of ⁹ (17.5 mg), a 1 g marijuana cigarette containing 1.83% ⁹-THC, a synthetic cannabis compound (Nabilone 2 mg orally), and their respective placebos were assessed with self-report and operant work-contingent choice procedures. Three groups of eight subjects were selected on the basis of a history of regular, intermittent, or occasional marijuana-smoking behavior. All subjects served as their own controls for each drug condition and studies were carried out under double-blind and double-dummy conditions in a controlled, residential research ward. Placebo responding did not vary as a function of history of marijuana use, but the past history of drug use had a significant influence on the reinforcing properties of cannabis compounds as well as the behavioral and physiological effects of these drugs. Regular marijuana users reported a significant increase in elation following marijuana smoking, but this was not associated with a significant increment in pulse rate. Intermittent and occasional marijuana smokers had significant increases in pulse rate, but no significant marijuana-induced elation. Nabilone and ⁹-THC produced a significant increase in pulse rate for all subject groups, but there was no significant increase in elation following ingestion of these compounds. Given a choice between the three drugs and three placebos, 18 of 23 subjects worked to obtain a marijuana cigarette in an operant work choice paradigm. These data indicate that smoked marijuana was significantly more reinforcing than all other cannabis compounds studied, regardless of past drug-use history.     

Generalization of the discriminative stimulus properties of x0394; 9 in rats

Rats were trained in a water maze to discriminate between IP injections of 3 mg/kg ⁹- (⁹⁽¹¹⁾-THC) and its vehicle. Both ⁸- and ⁹⁽¹¹⁾ were generalized to the training drug. In contrast to our observations in rhesus monkeys, where ⁹-THC is at least 100 times less potent than ⁹-THC, ⁹⁽¹¹⁾ was found to be only seven times less potent in the rat. Relative potencies, expressed as the dosage at which 50% of the animals gave drug responses (ED₅₀) were 1.8 mg/kg and 12.2 mg/kg for ⁹-THC and ⁹⁽¹¹⁾ respectively. Twenty-four hours after receiving 7×ED₅₀=12 mg/kg ⁹ the tests showed intermediate results when conducted with the training dosage; 4×ED₅₀=50 mg/kg ⁹-THC 48 h prior to the training dosage of 3 mg/kg ⁹-THC completely blocked drug-appropriate responses. Coinjection of ED₅₀ dosages of ⁹- and ⁹⁽¹¹⁾-THC led to 90% drug responses, demonstrating the additivity of the cannabis-like effect of both cannabinoids. Differences in the individual sensitivity of the rats to the tested cannabinoids were observed. Findings are interpreted in terms of the receptor mechanism for cannabis-like activity.This paper is dedicated to the memory of Dr. M. Binder who died on February 15, 1984