Premium
Effects of Aging on the Opioid Modulation of Feeding in Humans
Author(s) -
MacIntosh Caroline G.,
Sheehan Jessica,
Davani Nusha,
Morley John E.,
Horowitz Michael,
Chapman Ian M.
Publication year - 2001
Publication title -
journal of the american geriatrics society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.992
H-Index - 232
eISSN - 1532-5415
pISSN - 0002-8614
DOI - 10.1046/j.1532-5415.2001.4911246.x
Subject(s) - medicine , bolus (digestion) , nausea , meal , (+) naloxone , anorexia , anesthesia , saline , opioid , receptor
OBJECTIVES: To determine whether aging is associated with a reduction in the opioid modulation of feeding, which may be important in the pathogenesis of the “anorexia of aging.” DESIGN: Three studies on separate days, in randomized order and double‐blind fashion. SETTING: Clinical Human Research Laboratory, Department of Medicine, RAH, Adelaide, Australia. PARTICIPANTS: Twelve older (5 male/7 female) (age 65–84) and 12 young (5 male/7 female) (age 20–26) healthy subjects. INTERVENTION: Subjects received in double‐blinded random order, intravenous bolus (10 minutes) and then continuous (140 minutes) infusions of saline (control), naloxone low dose (LD) (bolus 27 μg/kg; continuous 50 μg/kg/hr), or naloxone high dose (HD) (bolus 54.5 μg/kg; continuous 100 μg/kg/hr). MEASUREMENTS: After 120 minutes, subjects were offered a buffet meal, and their energy intake was quantified. Hunger, fullness, nausea, and drowsiness were assessed using visual analogue scales. RESULTS: The naloxone LD and HD infusions had no significant effect on ratings of hunger, fullness, or nausea, but increased drowsiness ( P < .01) compared with the control infusion in both age groups. Older subjects ate less ( P < .001) at the buffet meal than young subjects during all three infusions. Naloxone infusions reduced energy intake compared with control ( P < .001), LD by 13.2 ± 5.0% and HD by 10.7 ± 5.0%, with no difference between the doses ( P = .71). Overall, naloxone suppressed energy intake in both young and older subjects ( P < .01). This suppression was slightly, but not significantly, greater in young than in older subjects (mean of LD and HD 16.4 ± 4.9% vs 7.5 ± 4.9%, P = .42), because of a trend to reduced suppression in older women. CONCLUSIONS: We conclude that healthy older adults retain their sensitivity to the suppressive effects of naloxone on food intake. Possible gender differences in this sensitivity warrant further investigation. A decline in opioid activity is unlikely to contribute substantially to the physiological anorexia of aging observed in older people.