The withdrawal syndrome after the cessation of μ-opioid receptor agonists remains an obstacle in the clinical treatment of pain. We recently showed that peripheral opioid receptors play a significant role in the withdrawal signs in morphine-dependent mice. Therefore, the present study was designed to investigate the underlying mechanism of morphine-induced withdrawal symptoms, especially the peripheral oriented body-weight loss that accompanied diarrhea, in mice. Withdrawal signs were precipitated by the injection of naloxone 1 day after the slow-release emulsion administration of morphine. Withdrawal body-weight loss and diarrhea precipitated by naloxone in morphine-dependent mice were significantly suppressed by ritanserin (a 5-HT2 receptor antagonist), olanzapine (5-HT2/D2 receptor antagonist) and fullerene (a free radical scavenger), whereas neither ondansetron (a 5-HT3 receptor antagonist) nor atropine (a muscarine receptor antagonist) significantly suppressed naloxone-precipitated diarrhea. 5-HT3-receptors (but not 5-HT2-receptors) are known to play a significant role in 5-HT-induced diarrhea. Therefore, we also examined the effects of ritanserin and fullerene on 5-HT-induced diarrhea in morphine-dependent mice. Ritaserin significantly suppressed 5-HT-induced diarrhea in morphine-dependent mice, but not saline-treated mice. These results suggest that peripheral 5-HT2-receptor function could be altered in morphine-dependent mice, and the blockade of 5-HT2 receptor or free radical scavengers may be useful for the treatment of opioid-withdrawal diarrhea.
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http://dx.doi.org/10.1016/j.ejphar.2014.07.009 | DOI Listing |
Heliyon
December 2024
Department of Biomedical Sciences, Pak Austria Fachhochschule: Institute of Applied Sciences and Technology, Haripur, Khyber Pakhtunkhwa, Pakistan.
Morphine belongs to the class of opioids and is known for its potential to cause dependence and addiction, particularly with prolonged use. Due to the associated risks, caution must be taken when prescribing and limiting its clinical use. Overexpression of N-methyl-D-aspartate (NMDA) receptors, nitric oxide and cGMP pathway has been implicated in exacerbate the development of morphine dependence and withdrawal.
View Article and Find Full Text PDFFASEB J
April 2024
Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, USA.
Recent evidence suggests that chronic exposure to opioid analgesics such as morphine disrupts the intestinal epithelial layer and causes intestinal dysbiosis. Depleting gut bacteria can preclude the development of tolerance to opioid-induced antinociception, suggesting an important role of the gut-brain axis in mediating opioid effects. The mechanism underlying opioid-induced dysbiosis, however, remains unclear.
View Article and Find Full Text PDFPsychopharmacology (Berl)
July 2024
Department of Comparative Pathobiology, Cummings School of Veterinary Medicine at Tufts University, 200 Westboro Rd, North Grafton, MA, USA.
Rationale: Transgenerational effects of preconception morphine exposure in female rats have been reported which suggest that epigenetic modifications triggered by female opioid exposure, even when that exposure ends several weeks prior to pregnancy, has significant ramifications for their future offspring.
Objective: The current study compares two mouse strains with well-established genetic variation in their response to mu opioid receptor agonists, C57BL/6J (BL6) and 129S1/svlmJ (129) to determine whether genetic background modifies the impact of preconception opioid exposure.
Methods: Adolescent females from both strains were injected daily with morphine for a total of 10 days using an increasing dosing regimen with controls receiving saline.
bioRxiv
January 2024
Center for the Neurobiology of Addiction, Pain, and Emotion (NAPE), University of Washington, Seattle, WA, 98195, USA.
Because opioid withdrawal is an intensely aversive experience, persons with opioid use disorder (OUD) often relapse to avoid it. The lateral septum (LS) is a forebrain structure that is important in aversion processing, and previous studies have linked the lateral septum (LS) to substance use disorders. It is unclear, however, which precise LS cell types might contribute to the maladaptive state of withdrawal.
View Article and Find Full Text PDFDrug Alcohol Depend
February 2024
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