Δ 9 -Tetrahydrocannabinol alleviates hyperalgesia in a humanized mouse model of sickle cell disease

Δ9-THC reduced pain hypersensitivity in a humanized mouse model of sickle cell disease. In mice expressing more than 99% human sickle hemoglobin, acute THC treatment dose-dependently reduced both mechanical and cold hypersensitivity and also produced substantial antinociceptive effects in a tail-flick pain test.

At 1 mg/kg, THC reduced pain sensitivity without altering anxiety-like behavior or long-term memory. With repeated treatment, THC continued to provide sustained relief from mechanical hypersensitivity, although tolerance developed to its effects on cold hypersensitivity.

The researchers concluded that THC may represent a potential option for managing chronic pain associated with sickle cell disease. These findings are especially notable because sickle cell pain is often severe and difficult to control, while current treatment frequently depends on opioid analgesics.

“People with sickle cell disease (SCD) often experience chronic pain as well as unpredictable episodes of acute pain, which significantly affect their quality of life and life expectancy. Current treatment strategies for SCD-associated pain primarily rely on opioid analgesics, which have limited efficacy and cause serious adverse effects.

Cannabis has emerged as a potential alternative, yet its efficacy remains uncertain. In this study, we investigated the antinociceptive effects of Δ9-tetrahydrocannabinol (THC), cannabis’ intoxicating constituent, in male HbSS mice, which express >99% human sickle hemoglobin, and male HbAA mice, which express normal human hemoglobin A, as a control.

Acute THC administration (0.1-3 mg-kg-1, intraperitoneal, i.p.) dose-dependently reduced mechanical and cold hypersensitivity in HbSS, but not HbAA mice. In the tail-flick assay, THC (1 and 3 mg-kg-1, i.p.) produced substantial antinociceptive effects in HbSS mice. By contrast, THC (1 mg-kg-1, i.p.) did not alter anxiety-like behavior (elevated plus maze) or long-term memory (24-h novel object recognition). Subchronic THC treatment (1 and 3 mg-kg-1, i.p.) provided sustained relief of mechanical hypersensitivity but led to tolerance in cold hypersensitivity in HbSS mice.

Together, the findings identify THC as a possible therapeutic option for the management of chronic pain in SCD. Further research is warranted to elucidate its mechanism of action and possible interaction with other cannabis constituents. 

Significance Statement The study explores THC’s efficacy in alleviating pain in sickle cell disease (SCD) using a humanized mouse model. Findings indicate that acute THC administration reduces mechanical and cold hypersensitivity in SCD mice without impacting emotional and cognitive dysfunction. Subchronic THC treatment offers sustained relief of mechanical hypersensitivity but leads to cold hypersensitivity tolerance. These results offer insights into THC’s potential as an alternative pain management option in SCD, highlighting both its benefits and limitations.”

https://pubmed.ncbi.nlm.nih.gov/38955494/

“The results indicate that acute THC administration alleviates mechanical and cold hypersensitivity in HbSS mice in a dose-dependent manner without affecting emotional and cognitive dysfunction also present in these mice.”

https://www.sciencedirect.com/science/article/abs/pii/S0022356524178147

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Disease-modifying effects of natural Δ9-tetrahydrocannabinol in endometriosis-associated pain.

In a mouse model of endometriosis, daily treatment with Δ9-THC reduced abdominal mechanical hypersensitivity and the unpleasantness associated with pain. THC also restored cognitive function in animals that had developed substantial memory deficits associated with endometriosis.

The effects went beyond pain relief. THC altered uterine innervation and, most notably, inhibited the development of endometrial cysts, suggesting a potential disease-modifying effect rather than simply masking symptoms.

These findings are important because endometriosis is a chronic condition in which pain, abnormal tissue growth, and neurological effects can all contribute to disease burden. The researchers concluded that the results support clinical investigation of THC as a potential treatment for women with endometriosis.

“Endometriosis is a chronic painful disease highly prevalent in women that is defined by growth of endometrial tissue outside the uterine cavity and lacks adequate treatment.

Medical use of cannabis derivatives is a current hot topic and it is unknown whether phytocannabinoids may modify endometriosis symptoms and development.

Here we evaluate the effects of repeated exposure to Δ9-tetrahydrocannabinol (THC) in a mouse model of surgically-induced endometriosis.

In this model, female mice develop mechanical hypersensitivity in the caudal abdomen, mild anxiety-like behavior and substantial memory deficits associated with the presence of extrauterine endometrial cysts.

Interestingly, daily treatments with THC (2 mg/kg) alleviate mechanical hypersensitivity and pain unpleasantness, modify uterine innervation and restore cognitive function without altering the anxiogenic phenotype. Strikingly, THC also inhibits the development of endometrial cysts.

These data highlight the interest of scheduled clinical trials designed to investigate possible benefits of THC for women with endometriosis.”

https://www.ncbi.nlm.nih.gov/pubmed/31931958

“These experiments suggest that THC may be a useful treatment for patients with endometriosis.”

https://elifesciences.org/articles/50356

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Inhibition of inflammatory hyperalgesia by activation of peripheral CB2 cannabinoid receptors.

“BACKGROUND:

Cannabinoid receptor agonists inhibit inflammatory hyperalgesia in animal models. Nonselective cannabinoid receptor agonists also produce central nervous system (CNS) side effects. Agonists selective for CB2 cannabinoid receptors, which are not found in the CNS, do not produce the CNS effects typical of nonselective cannabinoid receptor agonists but do inhibit acute nociception. The authors used the CB2 receptor-selective agonist AM1241 to test the hypothesis that selective activation of peripheral CB2 receptors inhibits inflammatory hyperalgesia.”

“CONCLUSIONS:

Local, peripheral CB2 receptor activation inhibits inflammation and inflammatory hyperalgesia. These results suggest that peripheral CB2 receptors may be an appropriate target for eliciting relief of inflammatory pain without the CNS effects of nonselective cannabinoid receptor agonists.”

http://www.ncbi.nlm.nih.gov/pubmed/14508331