The Involvement of the Endogenous Opioid System in the Gastrointestinal Aging in Mice and Humans

Abstract

Nearly 20% of elderly patients suffer from constipation, but the age-related changes in the gastrointestinal (GI) tract remain insufficiently elucidated. In this study, the alterations within the endogenous opioid system (EOS) as a potential cause of constipation in the elderly were evaluated. The GI functions were assessed in vitro and in vivo and compared between 6-, 12- and 18-month old mice. Moreover, the effect of opioid receptor (MOP, DOP, KOP) agonists on the mouse GI tract functions and the EOS components expression in mouse tissues and colonic biopsies from patients with functional constipation were determined. In the oldest mice, the GI peristalsis was significantly impaired as compared to the younger groups. The tissue response to MOP and DOP, but not KOP, agonists weakened with age in vitro; for DOP, it was confirmed in vivo. In the mouse upper GI tract, Oprm1, Oprd1, Oprk1 expression decreased with age; in the colon, Oprm1 expression increased. There were no differences in the expression of these genes in the colonic biopsies from patients >50 years old as compared to the younger group. In conclusion, the age-related impairment of the GI peristalsis may result from reduced MOP and DOP response to the activation with opioid agonists or the alterations in the EOS expression.

Association of dietary inflammatory index with constipation: Evidence from the National Health and Nutrition Examination Survey

“…Notably, constipation is often accompanied by bloating, abdominal pain, and a sense of unease (Bielefeldt et al., 2016 ). The etiology of digestive diseases is multifaceted, with factors such as low fiber intake, dehydration, adverse health behaviors, such as smoking, excessive alcohol consumption, and a lack of physical activity, all contributing to its development (Szymaszkiewicz et al., 2022 ). Moreover, depression can potentially impact the neuroendocrine system, consequently influencing gastrointestinal functions and leading to the onset or exacerbation of constipation (Wang et al., 2023 ).…”