Inhalation, parenteral and oral LD50 values of delta 9-tetrahydrocannabinol in Fischer rats

Toxic effects of AB-CHMINACA on liver and kidney and detection of its blood level in adult male mice

BACKGROUND

AB-CHMINACA is a cannabimimetic indazole derivative. In 2013, it was reported in different countries as a substance of abuse.

PURPOSE

This study evaluated the subacute toxic effects of AB-CHMINACA on the liver and kidneys and measured its blood level in adult male mice.

METHODS

The histological and biochemical subacute toxic effects on the liver and kidneys were assessed after four weeks of daily intraperitoneal injections of one of the following doses: 0.3 mg/kg, 3 mg/kg, or 10 mg/kg as the highest dose in adult male albino mice. In addition, the blood concentration level of AB-CHMINACA was determined by GC-MS-MS.

RESULTS

The histological effects showed congestion, hemorrhage, degeneration, and cellular infiltration of the liver and kidney tissues. Considering the control groups as a reference, biochemical results indicated a significant increase in the serum AST only in the highest dose group, while the ALT and creatinine levels did not significantly change. The mean values of AB-CHMINACA blood levels were 3.05 ± 1.16, 15.08 ± 4.30, and 54.43 ± 8.70 ng/mL for the three treated groups, respectively, one hour after the last dose of intraperitoneal injection. The calibration curves were linear in the 2.5-500 ng/mL concentration range. The intra-assay precision and accuracy of the method were less than 7.0% (RSD) and ± 9.2% (Bias).

CONCLUSION

This research supports the available case reports on AB-CHMINACA toxicity that it has low lethality; still, the chronic administration causes evident liver and kidney histotoxic effects even at low doses with unnoticeable clinical effects in mice.

Antinociceptive effect of plant-based natural products in chemotherapy-induced peripheral neuropathies: A systematic review

Chemotherapy-induced peripheral neuropathy (CIPN) is one of the most prevalent and difficult-to-treat symptoms in cancer patients. For this reason, the explore for unused helpful choices able of filling these impediments is essential. Natural products from plants stand out as a valuable source of therapeutic agents, being options for the treatment of this growing public health problem. Therefore, the objective of this study was to report the effects of natural products from plants and the mechanisms of action involved in the reduction of neuropathy caused by chemotherapy. The search was performed in PubMed, Scopus and Web of Science in March/2021. Two reviewers independently selected the articles and extracted data on characteristics, methods, study results and methodological quality (SYRCLE). Twenty-two studies were selected, describing the potential effect of 22 different phytochemicals in the treatment of CIPN, with emphasis on terpenes, flavonoids and alkaloids. The effect of these compounds was demonstrated in different experimental protocols, with several action targets being proposed, such as modulation of inflammatory mediators and reduction of oxidative stress. The studies demonstrated a predominance of the risk of uncertain bias for randomization, baseline characteristics and concealment of the experimental groups. Our findings suggest a potential antinociceptive effect of natural products from plants on CIPN, probably acting in several places of action, being strategic for the development of new therapeutic options for this multifactorial condition.

In Vivo Bio-Activation of JWH-175 to JWH-018: Pharmacodynamic and Pharmacokinetic Studies in Mice

3-(1-Naphthalenylmethyl)-1-pentyl-1H-indole (JWH-175) is a synthetic cannabinoid illegally marketed for its psychoactive cannabis-like effects. This study aimed to investigate and compare in vitro and in vivo pharmacodynamic activity of JWH-175 with that of 1-naphthalenyl (1-pentyl-1H-indol-3-yl)-methanone (JWH-018), as well as evaluate the in vitro (human liver microsomes) and in vivo (urine and plasma of CD-1 male mice) metabolic profile of JWH-175. In vitro binding studies showed that JWH-175 is a cannabinoid receptor agonist less potent than JWH-018 on mouse and human CB1 and CB2 receptors. In agreement with in vitro data, JWH-175 reduced the fESPS in brain hippocampal slices of mice less effectively than JWH-018. Similarly, in vivo behavioral studies showed that JWH-175 impaired sensorimotor responses, reduced breath rate and motor activity, and increased pain threshold to mechanical stimuli less potently than JWH-018. Metabolic studies demonstrated that JWH-175 is rapidly bioactivated to JWH-018 in mice blood, suggesting that in vivo effects of JWH-175 are also due to JWH-018 formation. The pharmaco-toxicological profile of JWH-175 was characterized for the first time, proving its in vivo bio-activation to the more potent agonist JWH-018. Thus, it highlighted the great importance of investigating the in vivo metabolism of synthetic cannabinoids for both clinical toxicology and forensic purposes.

Cannabis: A Toxin-Producing Plant with Potential Therapeutic Uses

For thousands of years, Cannabis sativa has been utilized as a medicine and for recreational and spiritual purposes. Phytocannabinoids are a family of compounds that are found in the cannabis plant, which is known for its psychotogenic and euphoric effects; the main psychotropic constituent of cannabis is Δ9-tetrahydrocannabinol (Δ9-THC). The pharmacological effects of cannabinoids are a result of interactions between those compounds and cannabinoid receptors, CB1 and CB2, located in many parts of the human body. Cannabis is used as a therapeutic agent for treating pain and emesis. Some cannabinoids are clinically applied for treating chronic pain, particularly cancer and multiple sclerosis-associated pain, for appetite stimulation and anti-emesis in HIV/AIDS and cancer patients, and for spasticity treatment in multiple sclerosis and epilepsy patients. Medical cannabis varies from recreational cannabis in the chemical content of THC and cannabidiol (CBD), modes of administration, and safety. Despite the therapeutic effects of cannabis, exposure to high concentrations of THC, the main compound that is responsible for most of the intoxicating effects experienced by users, could lead to psychological events and adverse effects that affect almost all body systems, such as neurological (dizziness, drowsiness, seizures, coma, and others), ophthalmological (mydriasis and conjunctival hyperemia), cardiovascular (tachycardia and arterial hypertension), and gastrointestinal (nausea, vomiting, and thirst), mainly associated with recreational use. Cannabis toxicity in children is more concerning and can cause serious adverse effects such as acute neurological symptoms (stupor), lethargy, seizures, and even coma. More countries are legalizing the commercial production and sale of cannabis for medicinal use, and some for recreational use as well. Liberalization of cannabis laws has led to increased incidence of toxicity, hyperemesis syndrome, lung disease cardiovascular disease, reduced fertility, tolerance, and dependence with chronic prolonged use. This review focuses on the potential therapeutic effects of cannabis and cannabinoids, as well as the acute and chronic toxic effects of cannabis use on various body systems.

Cannabis Extract CT-921 Has a High Efficacy-Adverse Effect Profile in a Neuropathic Pain Model

Background

Legalization of cannabis encourages the development of specific cultivars to treat disease such as neuropathic pain. Because of the large number of cultivars, it is necessary to prioritize extracts before proceeding to clinical trials.

Purpose

To compare extracts of two unique cannabis cultivars (CT-921, CT-928) for treatment of neuropathic pain induced by constriction of sciatic nerve in mice and to illustrate the use of this animal model to set priority for future trials.

Methods

Pain severity was measured by threshold force causing paw withdrawal. Dose-response relationships and time course were determined for intravenously injected extracts of cultivars and vehicle. The doses for allodynia relief were correlated with decreased respiratory rate, temperature and behavioral changes.

Results

Effective analgesic dose for 50 and 95% (ED_50An and ED_95An) was 15, and 29 mg/kg for CT-921 and 0.9 and 4.7 for CT-928. At ED_50An, for both extracts, the duration was 120 min. At ED_95An, administration of CT-928 significantly decreased respiratory rate while CT-921 did not. CT-928 decreased temperature more than CT-921. CT-928 produced frantic hyperactivity not seen with CT-921. At equivalent analgesic doses, THC was much less in CT-921 than in CT-928 suggesting interactions with components other than THC influenced the analgesia. At equivalent analgesic doses, efficacy-to-adverse effect profile for CT-928 was worse than for CT-921.

Conclusion

Both extracts relieved neuropathic pain; however, CT-921 had a better efficacy-to-adverse effect profile, a rational basis for prioritizing cultivars for future clinical evaluation.

Dark Classics in Chemical Neuroscience: Δ9-Tetrahydrocannabinol

Cannabis ( Cannabis sativa) is the most widely used illicit drug in the world, with an estimated 192 million users globally. The main psychoactive component of cannabis is (-)- trans-Δ⁹-tetrahydrocannabinol (Δ⁹-THC), a compound with a diverse range of pharmacological actions. The unique and distinctive intoxication caused by Δ⁹-THC primarily reflects partial agonist action at central cannabinoid type 1 (CB₁) receptors. Δ⁹-THC is an approved therapeutic treatment for a range of conditions, including chronic pain, chemotherapy-induced nausea and vomiting, and multiple sclerosis, and is being investigated in indications such as anorexia nervosa, agitation in dementia, and Tourette's syndrome. It is available as a regulated pharmaceutical in products such as Marinol, Sativex, and Namisol as well as in an ever-increasing range of unregistered medicinal and recreational cannabis products. While cannabis is an ancient medicament, contemporary use is embroiled in legal, scientific, and social controversy, much of which relates to the potential hazards and benefits of Δ⁹-THC itself. Robust contemporary debate surrounds the therapeutic value of Δ⁹-THC in different diseases, its capacity to produce psychosis and cognitive impairment, and the addictive and "gateway" potential of the drug. This review will provide a profile of the chemistry, pharmacology, and therapeutic uses of Δ⁹-THC as well as the historical and societal import of this unique, distinctive, and ubiquitous psychoactive substance.

DNA Damaging Effects, Oxidative Stress Responses and Cholinesterase Activity in Blood and Brain of Wistar Rats Exposed to Δ9-Tetrahydrocannabinol

Currently we are faced with an ever-growing use of Δ9-tetrahydrocannabinol (THC) preparations, often used as supportive therapies for various malignancies and neurological disorders. As some of illegally distributed forms of such preparations, like cannabis oils and butane hash oil, might contain over 80% of THC, their consumers can become intoxicated or experience various detrimental effects. This fact motivated us for the assessments of THC toxicity in vivo on a Wistar rat model, at a daily oral dose of 7 mg/kg which is comparable to those found in illicit preparations. The main objective of the present study was to establish the magnitude and dynamics of DNA breakage associated with THC exposure in white blood and brain cells of treated rats using the alkaline comet assay. The extent of oxidative stress after acute 24 h exposure to THC was also determined as well as changes in activities of plasma and brain cholinesterases (ChE) in THC-treated and control rats. The DNA of brain cells was more prone to breakage after THC treatment compared to DNA in white blood cells. Even though DNA damage quantified by the alkaline comet assay is subject to repair, its elevated level detected in the brain cells of THC-treated rats was reason for concern. Since neurons do not proliferate, increased levels of DNA damage present threats to these cells in terms of both viability and genome stability, while inefficient DNA repair might lead to their progressive loss. The present study contributes to existing knowledge with evidence that acute exposure to a high THC dose led to low-level DNA damage in white blood cells and brain cells of rats and induced oxidative stress in brain, but did not disturb ChE activities.

Behavioral Characterization of the Effects of Cannabis Smoke and Anandamide in Rats

Cannabis is the most widely used illicit drug in the world. Delta-9-tetrahydrocannabinol (Δ9-THC) is the main psychoactive component of cannabis and its effects have been well-studied. However, cannabis contains many other cannabinoids that affect brain function. Therefore, these studies investigated the effect of cannabis smoke exposure on locomotor activity, rearing, anxiety-like behavior, and the development of dependence in rats. It was also investigated if cannabis smoke exposure leads to tolerance to the locomotor-suppressant effects of the endogenous cannabinoid anandamide. Cannabis smoke was generated by burning 5.7% Δ9-THC cannabis cigarettes in a smoking machine. The effect of cannabis smoke on the behavior of rats in a small and large open field and an elevated plus maze was evaluated. Cannabis smoke exposure induced a brief increase in locomotor activity followed by a prolonged decrease in locomotor activity and rearing in the 30-min small open field test. The cannabinoid receptor type 1 (CB1) receptor antagonist rimonabant increased locomotor activity and prevented the smoke-induced decrease in rearing. Smoke exposure also increased locomotor activity in the 5-min large open field test and the elevated plus maze test. The smoke exposed rats spent more time in the center zone of the large open field, which is indicative of a decrease in anxiety-like behavior. A high dose of anandamide decreased locomotor activity and rearing in the small open field and this was not prevented by rimonabant or pre-exposure to cannabis smoke. Serum Δ9-THC levels were 225 ng/ml after smoke exposure, which is similar to levels in humans after smoking cannabis. Exposure to cannabis smoke led to dependence as indicated by more rimonabant-precipitated somatic withdrawal signs in the cannabis smoke exposed rats than in the air-control rats. In conclusion, chronic cannabis smoke exposure in rats leads to clinically relevant Δ9-THC levels, dependence, and has a biphasic effect on locomotor activity.

Endocannabinoids in cerebrovascular regulation

The cerebral blood flow is tightly regulated by myogenic, endothelial, metabolic, and neural mechanisms under physiological conditions, and a large body of recent evidence indicates that inflammatory pathways have a major influence on the cerebral blood perfusion in certain central nervous system disorders, like hemorrhagic and ischemic stroke, traumatic brain injury, and vascular dementia. All major cell types involved in cerebrovascular control pathways (i.e., smooth muscle, endothelium, neurons, astrocytes, pericytes, microglia, and leukocytes) are capable of synthesizing endocannabinoids and/or express some or several of their target proteins [i.e., the cannabinoid 1 and 2 (CB1 and CB2) receptors and the transient receptor potential vanilloid type 1 ion channel]. Therefore, the endocannabinoid system may importantly modulate the regulation of cerebral circulation under physiological and pathophysiological conditions in a very complex manner. Experimental data accumulated since the late 1990s indicate that the direct effect of cannabinoids on cerebral vessels is vasodilation mediated, at least in part, by CB1 receptors. Cannabinoid-induced cerebrovascular relaxation involves both a direct inhibition of smooth muscle contractility and a release of vasodilator mediator(s) from the endothelium. However, under stress conditions (e.g., in conscious restrained animals or during hypoxia and hypercapnia), cannabinoid receptor activation was shown to induce a reduction of the cerebral blood flow, probably via inhibition of the electrical and/or metabolic activity of neurons. Finally, in certain cerebrovascular pathologies (e.g., subarachnoid hemorrhage, as well as traumatic and ischemic brain injury), activation of CB2 (and probably yet unidentified non-CB1/non-CB2) receptors appear to improve the blood perfusion of the brain via attenuating vascular inflammation.

Role of endocannabinoids and cannabinoid-1 receptors in cerebrocortical blood flow regulation

Background

Endocannabinoids are among the most intensively studied lipid mediators of cardiovascular functions. In the present study the effects of decreased and increased activity of the endocannabinoid system (achieved by cannabinoid-1 (CB1) receptor blockade and inhibition of cannabinoid reuptake, respectively) on the systemic and cerebral circulation were analyzed under steady-state physiological conditions and during hypoxia and hypercapnia (H/H).

Methodology/Principal Findings

In anesthetized spontaneously ventilating rats the CB1-receptor antagonist/inverse agonist AM-251 (10 mg/kg, i.v.) failed to influence blood pressure (BP), cerebrocortical blood flow (CoBF, measured by laser-Doppler flowmetry) or arterial blood gas levels. In contrast, the putative cannabinoid reuptake inhibitor AM-404 (10 mg/kg, i.v.) induced triphasic responses, some of which could be blocked by AM-251. Hypertension during phase I was resistant to AM-251, whereas the concomitant CoBF-increase was attenuated. In contrast, hypotension during phase III was sensitive to AM-251, whereas the concomitant CoBF-decrease was not. Therefore, CoBF autoregulation appeared to shift towards higher BP levels after CB1-blockade. During phase II H/H developed due to respiratory depression, which could be inhibited by AM-251. Interestingly, however, the concomitant rise in CoBF remained unchanged after AM-251, indicating that CB1-blockade potentially enhanced the reactivity of the CoBF to H/H. In accordance with this hypothesis, AM-251 induced a significant enhancement of the CoBF responses during controlled stepwise H/H.

Conclusion/Significance

Under resting physiological conditions CB1-receptor mediated mechanisms appear to have limited influence on systemic or cerebral circulation. Enhancement of endocannabinoid levels, however, induces transient CB1-independent hypertension and sustained CB1-mediated hypotension. Furthermore, enhanced endocannabinoid activity results in respiratory depression in a CB1-dependent manner. Finally, our data indicate for the first time the involvement of the endocannabinoid system and CB1-receptors in the regulation of the cerebral circulation during H/H and also raise the possibility of their contribution to the autoregulation of CoBF.

Changes in body temperature after administration of antipyretics, LSD, delta 9-THC and related agents: II

Antipyretics, in particular acetaminophen, aspirin and ibuprofen, constitute the single most important class of drugs used therapeutically for an effect on body temperature. Hallucinogens exert prominent actions on the central nervous system, and it is not surprising that, like so many other centrally-acting agents, they too often affect temperature. This compilation primarily covers the considerable amount of data published from 1981 through 1985 on the interactions of these drugs and thermoregulation, but data from many earlier papers not included in a previous compilation are also tabulated. The effects of agents not classically considered as antipyretics on temperatures of febrile subjects are also covered. The information listed includes the species used, the route of administration and dose of drug, the environmental temperature at which experiments were performed, the number of tests, the direction and magnitude of change in body temperature and remarks on special conditions, such as age or brain lesions. Also indicated is the influence of other drugs, such as antagonists, on the response to the primary agent.

Marihuana and sex: a critical survey

Marihuana usage is associated with a life-style that involves earlier and more frequent sexual activity. Marihuana usage does not affect human male testosterone levels significantly, but does adversely affect sperm production. Animal studies have not found consistent changes in weights of male sexual organs but have corroborated the adverse effects of cannabinoid compounds on sperm production. The biological significances of these effects on sperm production are unclear, however, since there is no evidence that human marihuana users or male animals given cannabinoid compounds are less fertile or are at risk for dominant lethal mutations. Cannabinoid compounds reliably inhibit ovulation in animals and are associated with depressed luteinizing hormone (LH) levels in both female and male animals. The decreased LH levels appear to be due to both hypothalamic and ovarian sites of action. Treatment with cannabinoid compounds is also associated with lower testosterone levels in male and lower prolactin levels in female animals. Effects on progesterone levels are inconclusive. Cannabinoid compounds do not possess estrogenic activity. Despite some consistencies in the data in virtually every study conducted with animals, there has been a basic confounding between direct drug action and secondary effects resulting from drug-induced decreases in food and water consumption and attendant weight loss. Almost all of the adverse effects of cannabinoid exposure on reproductive organs can be attributed to these secondary effects.

Cannabinoid-induced hormone changes in monkeys and rats

Previous findings at various laboratories indicated that cannabinoids distribute to sexual behavior centers in the brain, and endocrine aberrations have consistently been observed in animals treated with cannabis constituents. Subacute and chronic studies were performed to monitor hormone changes in rats and monkeys exposed to marihuana smoke or pure cannabinoids. In oral studies, young Fischer rats of both sexes were given delta 9-tetrahydrocannabinol (delta 9-THC) doses of 2, 10, or 50 mg/kg for 14--180 d and pregnant rats received 1, 5 or 10 mg/kg during gestation and lactation. Other male rats were exposed to marihuana smoke at delta 9-THC doses of 2 or 4 mg/kg for 14 d. Rhesus monkeys of either sex were given oral cannabidiol doses of 30, 100, and 300 mg/kg for 90 d. Serum pituitary, steroid, and thyroid hormone levels were determined by radioimmunoassay. Marihuana smoke (and oral delta 9-THC) depressed testosterone 20--30% and triiodothyronine 17--29%. In pregnant rats, small doses of delta 9-THC suppressed luteinizing hormone, but larger doses elevated both follicle-stimulating hormone and estrogens (approximately 50--100%) without affecting progesterone levels. Prolonged oral administration of delta 9-THC to young rats tended to increase gonadotropins, to which tolerance developed in males. Cannabidiol-treated monkeys responded with slight elevations in luteinizing hormone and follicle-stimulating hormone in males, whereas steroid hormones were essentially unchanged for both sexes. Hormone imbalance may explain cannabinoid-induced embryotoxicity and impaired gonadal function.

Influence of fasting on the absorption and effects of delta9-tetrahydrocannabinol after oral administration in sesame oil

Tissue levels of 3H were higher 2 hr after oral administration of 3H-delta9-THC (10 mg/kg in sesame oil) to male Fischer rats in the morning compared with treatment in the afternoon. A corresponding reduction in potency was seen for the impairing effect of delta9-THC on performance of a conditioned avoidance response (CAR). The hypothesis that these effects were related to the interval between feeding (which normally occurs during the night in the nocturnal rat) and drug administration was supported when they were mimicked in overnight fasted and ad lib fed rats. Food deprivation decreased the rate of gastrointestinal absorption of 14C-delta9-THC in sesame oil. Peak plasma levels of 14C occurred 2-4 hr after administration in fed rats compared with 8 hr in fasted rats. When tested 2 hr after oral administration, delta9-THC caused significantly greater impairment of CAR performance in fed than fasted rats, whereas the opposite was found after 8 hr. Extraction and subsequent thin layer chromatography of plasma and brain from fed and fasted rats sacrificed 2 or 8 hr after oral administration of 10 mg/kg 14C-delta9-THC showed that brain levels of 11-hydroxy-delta9-THC rather than delta9-THC were correlated with the behavioral effect.