RT Journal Article
SR Electronic
T1 Effect of aging on alpha-1 adrenergic stimulation of phosphoinositide hydrolysis in various regions of rat brain.
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 1265
OP 1270
VO 255
IS 3
A1 Burnett, D M
A1 Bowyer, J F
A1 Masserano, J M
A1 Zahniser, N R
YR 1990
UL http://jpet.aspetjournals.org/content/255/3/1265.abstract
AB The effects of aging were examined on the ability of alpha-1 adrenergic receptor agonists to stimulate phosphoinositide hydrolysis in three brain regions. Tissue minces of thalamus, cerebral cortex and hippocampus from 3-, 18- and 28-month-old male Fischer 344 rats were prelabeled with [3H]myoinositol. Exposure of these prelabeled minces to phenylephrine and (-)-norepinephrine revealed that accumulation of [3H]inositol phosphates was selectively reduced by 20 to 30% in the thalamus and cerebral cortex of the oldest age group. Analysis of concentration-response and competition binding curves indicated that this decrease was due to diminished agonist efficacy rather than diminished receptor affinity. The reduction in responsiveness to phenylephrine and (-)-norepinephrine in the cerebral cortex and the lack of any changes in the hippocampus parallel previously reported changes in the density of alpha-1 adrenergic receptors with aging. These data indicate that the ability of alpha-1 adrenergic receptor agonists to stimulate phosphoinositide hydrolysis is reduced in some, but not all, brain regions of aged Fischer 344 rats.