Chemical basis of hashish activity.

A sample of hashish was extracted consecutively with petroleum ether, benzene, and methanol. When tested intravenously in monkeys only the petroleum-ether fraction was active. This material was further fractionated. The only active compound isolated was Delta(1)-tetrahydrocannabinol. Cannabinol, cannabidiol, cannabichromene, cannabigerol, and cannabicyclol when administered together with Delta(1)-tetrahydrocannabinol do not cause a change in the activity of the latter, under the experimental conditions used. These results provide evidence that, except for Delta(1)-tetrahydrocannabinol, no other major, psychotomimetically active compounds are present in hashish.

6 -hydroxy- 1 -tetrahydrocannabinol synthesis and biological activity.

6beta-Hydroxy-delta(1)-tetrahydrocannabinol, a metabolite of delta(1)-tetrahydrocannabinol has been synthesized from delta(6)-tetrahydrocannabinol. It shows high tetrahydrocannabinol-type activity in rhesus monkeys. The implications of this funding are discussed.

Activity of novel aminocannabinoids in baboons.

The axial and equatorial isomers of 7-(methylamino)hexahydrocannabinol (1 and 2) and 7-(dimethylamino)hexahydrocannabinol (3 and 4) were prepared by reductive amination of the corresponding cannabinoid aldehydes. The amines caused some tranquility in baboons but did not evoke the typical cannabimimetic syndrome caused by psychoactive cannabinoids. However the axial amines (1 and 3) but not the equatorial ones (2 and 4) caused bouts of scratching and yawning. The latter is a rare pharmacological effect hitherto not observed with other cannabinoids.

Stereochemical requirements for cannabinoid activity.

Several pairs of cannabinoid isomers were synthesized and tested for psychotropic activity in rhesus monkeys. Two regularities were observed: (a) In the absence of the other substituents, the equatorial stereochemistry of the substituent at C-1 determines activity. (b) Two groups of THC-type cannabinoids which differ only in that the chemical groupings in one of them at C-1, C-2 are situated at C-1, C-6 in the other (but retain their stereochemistry) have almost equivalent psychotropic activity.

The gamma-aminobutyric acid system in rat cerebellum during cannabinoid-induced cataleptoid state.

Repeated, but not single, intraperitoneal injections of delta1,6-tetrahydrocannabinol (delta1,6-THC) 20 mg/kg to rats administered daily for two weeks, produced increased gamma-aminobutyric acid (GABA) concentration and decreased glutamic acid decarboxylase (GAD) activity in the cerebellum, as well as enhancement of [3H]-GABA uptake by cerebellar crude synaptosomes. It seems that the motor impairment elicited by delta1,6-THC was not associated with the GABA system, but presumably might be related to changes in brain excitability.

Sensitization of smooth muscle to plasma kinins: effects of enzymes and peptides on various preparations.

1. The influence of various materials, principally hydrolases and peptides, on the sensitivity to stimulating substances has been studied in a wide range of isolated and in vivo smooth muscle preparations.2. Chymotrypsin raised the susceptibility of the guinea-pig isolated ileum to peptides related to bradykinin and also sensitized isolated ileum and fundus of rat and albino gerbil to bradykinin. No sensitization to the kinin occurred in the following preparations: rat, gerbil and rabbit duodenum; rat colon and urinary bladder; dog tracheal chain; and rabbit jejunum. Chymotrypsin and peptides structurally related to the active centre of the enzyme did not affect the permeability increasing property of bradykinin in guinea-pig skin micro-circulation vessels. In contrast, intravenously administered chymotrypsin markedly augmented the bronchoconstrictor action of the kinin.3. Ficin and pronase increased the sensitivity of guinea-pig ileum to bradykinin. Pronase also sensitized the gerbil ileum and this effect was abolished by previous treatment with di-isopropylfluorophosphonate (dyflos). Pronase destroyed bradykinin after incubation.4. Reduced glutathione potentiated the response to bradykinin of guinea-pig ileum but did not affect its sensitivity. The potentiation also occurred in a chymotrypsin-treated preparation.5. It is assumed that specific sensitization elicited by proteinases might derive from an effect on the protein envelope of smooth muscle membrane.

A central vasodepressor effect of Dyflos.

1 Cats were anaesthetized with pentobarbitone sodium and atropinized peripherally by intravenous injection of atropine methyl nitrate; the effect was examined of topical bilateral application of dyflos to the ventral surface of the medulla oblongata at a region lateral to the pyramids and caudal to the trapezoid bodies. Dyflos was applied by means of perspex rings; the volume of fluid placed in each ring was 10 mul.2 The topical application of dyflos (1-20 mg/ml) produced a fall in arterial blood pressure without changes in heart rate and, in experiments without artificial ventilation, tachypnoea with dissociation of thoracic and abdominal respiration.3 Atropine methyl nitrate (50 mg/ml) applied topically in the same way as dyflos, prevented or abolished its vasodepressor effect.4 The two reactivators of acetylcholinesterase, obidoxime (100-200 mg/ml) and pralidoxime mesylate (100-200 mg/ml), applied topically in the same way as dyflos, abolished its vasodepressor effect. The reactivator compound 30 (100 mg/ml), also a pyridinium aldoxime, did not have this effect.5 Obidoxime and pralidoxime mesylate also reversed the vasodepression produced by carbachol applied to the ventral surface of the brain stem but not the vasodepression produced by glycine similarly applied.6 The problem is discussed as to whether the reversal of the dyflos and carbachol-induced vasodepression by obidoxime and pralidoxime is due to acetylcholinesterase reactivation by dephosphorylation and decarbamylation respectively, to a central atropine-like action of these compounds or to a combination of both.

Ciliary motility in brain ventricular system and trachea of hamsters.

Ciliary beat frequency (CBF) in various parts of brain ventricular system, as well as in trachea of hamsters, was examined. Coronal sections of brain and tracheal rings were maintained in a thermostatically controlled perfusion chamber and CBF measured by a photoelectric system equipped with a fiber-optic probe. CBF (Hz) values of lateral ventricle, aqueduct and fourth ventricle were 27.9 +/- 4.6; 30.7 +/- 7.7 and 31.9 +/- 7.8 Hz, respectively. CBF in the third ventricle--19.8 +/- 7.1 Hz--was significantly lower than in other segments of ventricular system. CBF in choroid plexus cilia was very slow, 5-10 Hz, whereas in tracheal rings amounted to 13.7 +/- 3.1 Hz. Bovine cervical mucus and mucus stimulant reversibly inhibited CBF in brain but not in trachea. Brain cilia in contrast to those in trachea were not capable of transporting particles. In addition to demonstrating differences between tracheal and ependymal cilia, this work suggests that cilial motility plays a functional role in local mixing of cerebrospinal fluid, but does not relate to the bulk flow within the ventricular system.

An improved preparation for determination of bradykinin.

The cat isolated jejunum kept either in an organ-bath or under superfusion can be rendered extremely sensitive to bradykinin after exposure to chymotrypsin. Treated preparations responded to as little as 100 pg/ml of the peptide. Use has been made of sensitized preparations to determine bradykinin-like material of dog blood extracts obtained in experimental "dumping syndrome".

Blood kinin system in renal hypertensive patients administered with SQ 20881.

The i.v. administration of 0.25 mg/kg SQ 20881 to eight renal hypertensive patients caused blood pressure fall and in five of them also reduced heart rate. The latter was attributed to increase in vagal tone. Peripheral and renal blood samples taken at the nadir of the hypotensive response showed considerable inhibition of plasma kininase activity, rise in free kinin level and reduced kininogen content. This reduction was not due to increased consumption as shown by in vitro experiments. PGE2 and PGF2 alpha levels in kidney blood of three patients remained practically unchanged. Plasma renin activity was augmented to a larger extent in blood of kidney with stenotic artery than in the one with patent vessel. It is concluded that the action of SQ 20881 on human blood kinin system, besides inhibition of kininase, involves also reduction of kininogen, the mechanism of which remains to be clarified.

Pyrenebutyl-methylphosphonofluoridate: a fluorescent anti-cholinesterase in vivo.

In vivo properties of pyrenebutyl-methylphosphonofluoridate (PBMPF) have been studied. The LD50 (i.v.) for mice was 15 mg/kg and toxic symptoms were typical of cholinesterase (ChE) inhibition but central signs were absent. After intraventricular injection of PBPMPF in unanaesthetized rabbits, continued walking in bizarre circular fashion together with peripheral vascular dilation and tachypnoea were observed. Recovery occurred 3 h post-injection. Fluorescent particles of unabsorbed material juxtaposed on lining ependyma were observed up to 14 days of administration. In addition, a large number of hippocampal cells showed vivid fluorescence, particularly in the cytoplasm, which was attributed to ChE inhibition. It is concluded that PBMPF seems promising as an organophosphate marker of nerve cells.

Models to predict cannabinoid-induced disturbances.

The most commonly used animal models to evaluate the psychoactivity of cannabinoids have been reviewed. The need for suitable models is acute considering the present interest to develop drugs based on the cannabinoid moiety but preferably dissociated from psychoactivity. Conceivably, a satisfactory assay should show features of cannabinoid-induced disturbances relevant to man as well as sensitivity, specificity and simplicity. These requisites seemed better fulfilled in the monkey model. Various lines of evidence have demonstrated the close pattern of the behavioural response to psychoactive and inactive cannabinoids in man and monkeys. Rhesus monkeys showed development of tolerance and withdrawal symptoms, which have been frequently reported in humans after prolonged exposure to cannabinoids. The exposure was reported also to cause in monkeys alterations of electrical activity and organic damage in deep brain structures. The monkey model has been particularly useful to determine the relative potency of naturally occurring cannabinoids and metabolites, which was adequately compared to that in man, and to establish the structural requirements for psychoactivity in large series of synthetic new compounds. In addition it appeared that rhesus monkeys react similarly to man with respect to proposed antidotes against cannabinoids. Four newly synthetized amino-cannabinoids were tested in baboons. All these compounds were virtually void of typical cannabinoid psychoactivity but two trans-analogs differed from the cis-analogs in that they provoked bouts of vigorous scratching and yawning. This unusual drug-effect, at difference from scratching alone has not been previously observed after administration of cannabinoids. In this presentation some terms of cannabis terminology have been discussed.

Yohimbine antagonism of the vasodepression elicited by organophosphates applied on ventral medulla oblongata.

The rostral ventral surface of medulla oblongata (RVMO) has been shown to constitute a selective target for organophosphate (op) cholinesterase inhibitors. The action of soman (S) as compared with (7-nitrobenz-2-oxa-1,3 diazole)aminopentyl methylphosphonofluoridate (NBD-AP-MPF), a fluorescent organophosphate has now been examined in anesthetized cats pretreated with atropine sulphate. Blood pressure (BP), electrocardiogram (ECG) and respiration (R) were recorded. In some animals a cannula was implanted into the right lateral ventricle. Chemicals were bilaterally applied on RVMO by means of a perspex cannula and removed after 5 min. The application of 2.5 micrograms S or 60 micrograms NBD-AP-MPF elicited severe fall of BP which recovered only after 2 h in the case of the former and up to 45 min in the latter. Smaller doses produced corresponding responses of lesser magnitude. Accompanying R changes consisted in most cases of increased rate and reduced amplitude whereas in others the opposite or mixed alterations occurred. Frequently, sigh-like movements intermingled at periodic intervals with regular R deflections. The sighs were interpreted as aiming to correct blood gases balance. After application of atropine on RVMO--but not by systemic administration--BP and R were restored whereas single repeated i.v. injection of 1 microgram/kg noradrenaline produced only transient reversals without influencing the course of long lasting vasodepression. In contrast, the intraventricular administration of 250-500 micrograms yohimbine considerably reduced both the magnitude and extent of the vasodepression elicited by topically applied organophosphates. It is postulated that central alpha 2-adrenoceptors in contrast to vascular sites are likely involved in the op-induced vasodepression. The present work provides an indication that effective antagonists might be developed considering blockade of these receptors.

Disposition of phencyclidine after intramuscular administration.

The disposition of radioactive phencyclidine (PCP) in various rat tissues, after single or repeated intramuscular injections for 23 days, have been investigated. Peak levels of radioactivity appeared 45-90 min after a single administration. The pancreas, salivary glands and mesenteric fat contained 4 to 6-fold higher radioactivity than brain, muscles, tendons, and bones. After repeated 3H-PCP injections, radioactivity levels showed a similar pattern as to that of the peak levels after a single administration, but at notably higher values. On the other hand, the percentage of depletion, within 48 h after the final injection, was the highest in the pancreas, salivary glands and mesenteric fat. It is possible that despite the low retention capacity of PCP radioactivity per unit weight of muscle, tendon and bone, they may be considered important reservoirs for either PCP, or its metabolites or both because of their large relative mass in the body.