Age-related decrements in the analgesic and hyperphagic responses to 2-deoxy-D-glucose

Among the compromised physiological responses affected by aging is an impaired response to glucose. Since administration of 2-deoxy-D-glucose (2DG) produces both analgesic and hyperphagic responses in young adult rats, the present study examined whether systematic variations in these responses occurred as a function of age. Separate cohorts of 4, 9, 14, 19 and 24 month old female rats received ascending doses of 2DG (0, 50, 250, 450, 650 mg/kg) with tail-flick latencies and jump thresholds assessed 30, 60 and 120 min later. Then the same rats received 2DG injections (0, 650, 1200 mg/kg) and food intake was assessed 5 hr later. Significant decreases in 2DG analgesia were observed on the tail-flick test as a function of age with the maximal decrease observed at the highest 2DG dose. Significant decreases in 2DG analgesia were generally observed on the jump test as a function of age, although this effect was not as robust as that observed on the tail-flick test. Finally, significant and systematic decreases in 2DG hyperphagia were observed as a function of age following both the 650 mg/kg and the 1200 mg/kg doses. The observed decrements in the analgesic and hyperphagic responses to 2DG as a function of age appear to represent an orderly alteration in responses to glucoprivation through adulthood.