Analgesic effect of quetiapine in a mouse model of cancer-induced bone pain

BACKGROUND/AIMS: Cancer-induced bone pain (CIBP) is one of the most common pains in patients with advanced neoplasms. Because of treatment-associated side effects, more than half of cancer patients are reported to have inadequate and undermanaged pain control. New mechanism-based therapies must be developed to reduce cancer pain. Quetiapine is a commonly used atypical antipsychotic drug. We report a study of the potential analgesic effects of quetiapine in a mouse model of CIBP and examine the mechanism of bone pain by analyzing the expression of various nociceptors. METHODS: Fifteen male C3H/HeN mice were arbitrarily divided into five groups: control and, CIBP with no treatment, quetiapine treatment, opioid treatment, and melatonin treatment. The mice were tested for mechanical hyperalgesia by determining the nociceptive hind paw withdrawal pressure threshold. Tissues from tibia were removed and subjected to quantitative and qualitative evaluations of transient receptor potential vanilloid 1 (TRPV1), TRPV4, acid-sensing ion channel 1 (ASIC1), ASIC2, and ASIC3 expression. RESULTS: Paw withdrawal pressure threshold was improved in the quetiapine treatment group compared with the CIBP group. Expression of TRPV1, TRPV4, ASIC1, ASIC2, and ASIC3 in the CIBP with quetiapine treatment group was significantly lower than that in the CIBP group. CONCLUSIONS: Our results suggest an analgesic effect of quetiapine in the CIBP animal model and implicate TRPV and ASICs as potential targets for cancer pain management.

Glucose Metabolism in the Intestine

Few are familiar with the gluconeogenesis that occurs in the intestine under fasting or the influence of insulin. Recently, however, studies that revealed the function of intestinal gluconeogenesis as a regulatory process for glucose homeostasis and appetite were described. The intestine produces about 25% of total endogenous glucose during fasting and regulates energy homeostasis through communication with the brain. Glucose produced via intestinal gluconeogenesis is delivered to portal vein where periportal neural system senses glucose and sends a signal to the brain to regulate appetite and glucose homeostasis. Moreover, studies uncovered that intestinal gluconeogenesis contributes to the rapid metabolic improvements induced by gastric bypass surgery.

Expression of Pain Receptors by Arthritis Treatment in Collagen Induced Murine Model of Rheumatoid Arthritis

OBJECTIVE: Rheumatoid arthritis, the most common form of arthritis, is typically characterized by induced inflammatory pain in joints. Recent studies have reported on the expression of pain receptors such as transient receptor potential vanilloid 1 (TRPV1) and acid sensing ion channel 3 (ASIC3), which are related to pain induction and regulation. This study was conducted to investigate the expression of TRPV1 and ASIC3 in response to the analgesic effect of an arthritis treatment in a collagen-induced arthritis (CIA). METHODS: Mice were divided into 3 groups: Control, CIA, and CIA with arthritis treatment. Mice received intraperitoneal injection with 10 mg/kg infliximab and 10 mg/kg meloxicam five times per week for 3 weeks. Mechanical hyperalgesia, histologic examination of the feet, serum levels of inflammatory cytokine such as interleukin-6 (IL-6), and interleukin-17 (IL-17), TRPV1 and ASIC3 expression were investigated. RESULTS: The serum levels of IL-6 and IL-17 were lower in the treatment group (73.77+/-10.11 pg/mL and 26.75+/-7.17 pg/mL, respectively) compared to the CIA group (p<0.001). Histological analysis showed decreased synovial cell proliferation, leukocyte infiltration, and cartilage destruction in the treatment group compared with the CIA group. The CIA group that underwent arthritis treatment showed a significantly increased withdrawal threshold of mechanical nociception on the hind paw and increased expression of TRPV1 and ASIC3 compared to the CIA group. CONCLUSION: Arthritis treatment resulted in an anti-inflammatory and analgesic effect through upregulation of the activity of TRPV1 and ASIC3 in CIA mice.