ENHANCEMENT OF GABA-ACTIVATED MEMBRANE CURRENTS IN AGED FISCHER-344 RAT BASAL FOREBRAIN NEURONS

Changes in GABAergic systems have been widely documented during development. Similar changes might also occur during aging, but little information is currently available. Whole-cell and single-channel GABA(A)-activated currents were studied in acutely dissociated basal forebrain neurons. An age-related increase in whole-cell GABA currents was observed in cells from aged (19-25 month) Fischer 344 rats. The GABA current from aged animals displayed a greater maximum response, with no change in EC(50) or slope of the GABA response curve. A reduction in use-dependent slow receptor desensitization was also observed in aged cells. Single-channel conductance and channel open time were unchanged with age, suggesting no alteration in the properties of single GABA channels. The benzodiazepine, midazolam, potentiated GABA currents to a greater degree in aged animals, consistent with previous reports of enhanced benzodiazepine activity with age. Ontogeny of the GABA(A) receptor/ion channel complex may continue through the stages of development, maturation, and aging.