Age-related reduction in responses of rat hippocampal neurons to locally applied monoamines.
Age-related changes in the responsiveness of hippocampal pyramidal neurons to norepinephrine (NE) and serotonin (5HT) were investigated using electrophysiological techniques. Local application of each monamine via pressure micro-ejection was employed to establish the dose which elicited a 50% change in spontaneous discharge rate of single pyramidal neurons; these data were used to construct dose response curves for the population of neurons tested in 3-6, 11-13, 18-20, and 27-30 month old rats. The percentage of cells responding in rats 18-20 and 27-30 months old decreased for both NE and 5HT. There was also a progressive increase with age in the population ED50 for 5HT starting at 18-20 months. For neurons which demonstrated a response to NE, no decrease in the population ED50 was observed. Taken together these data indicate that there is a progressive age-related decline in the postsynaptic response to NE and 5HT in the rodent hippocampus.
Bickford-Wimer
P C
PC
Veterans Administration Medical Center, Denver, CO 80220.
Miller
J A
JA
Freedman
R
R
Rose
G M
GM
D000200:Action Potentials / Q000187:drug effects; D000375:Aging / Q000502:physiology*; D000818:Animals; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D007478:Iontophoresis; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D051381:Rats; D011916:Rats, Inbred F344; D012701:Serotonin / Q000494:pharmacology*
D012701:Serotonin; D009638:Norepinephrine