Читать книгу Pathy's Principles and Practice of Geriatric Medicine - Группа авторов - Страница 366

Endogenous opioids play a role in mediating the short‐term sensory reward response to food. Exogenous administration of opioid agonists increases food intake in animals, and opioid antagonists decrease food intake in animals and adult humans.³⁴ There is evidence that ageing is associated with a reduced opioid feeding drive (reviewed by Horwitz et al.³⁵). Elderly patients with idiopathic, senile anorexia have lower plasma and CSF β‐endorphin concentrations than normal‐weight, age‐matched controls.³⁶ Intraperitoneal (i.p.) morphine injection increases food intake in young but not old mice, whereas i.p. naloxone decreases food intake in young but not older rats. Healthy older men are less sensitive to the inhibitory effects of subcutaneous naloxone on fluid intake than young men,³⁷ and in one small study of feeding in humans, the suppression of food intake by naloxone was non‐significantly greater in the older than young adults: 16 vs. 8%.³⁴ Overall, these results suggest that the stimulatory effect of endogenous opioids does decline somewhat with advancing age and may contribute to the anorexia of ageing. Further work is required to clarify these changes.