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Membrane Viscosity Correlates with α 1 ‐Adrenergic Signal Transduction of the Aged Rat Cerebral Cortex
Author(s) -
Miyamoto Atsushi,
Araiso Tsunehisa,
Koyama Tomiyasu,
Ohshika Hideyo
Publication year - 1990
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1990.tb08822.x
Subject(s) - cerebral cortex , adrenergic , signal transduction , neuroscience , medicine , endocrinology , transduction (biophysics) , membrane , biology , chemistry , microbiology and biotechnology , biophysics , receptor , biochemistry
We investigated, using adult (2‐month‐old) and senescent (12‐ and 24‐month‐old) rats, the effects of aging on the relationship between the α 1 ‐adrenergic coupling system and the membrane viscosity of the cerebral cortex. There was no age‐related difference in the K D values of [ 3 H]prazosin binding on the membranes. The B max values of [ 3 H]prazosin binding were reduced with advanced age. Norepinephrine induced formation of 3 H‐labeled inositol phosphates ( 3 H‐IPs) in the slices increased with advanced age. The EC 50 values for norepinephrine to stimulate the formation of 3 H‐IPs at advanced age were lower than that at adult age. The cholesterol content in membranes increased with advanced age. No changes in the phospholipid content in membranes were observed with advanced age. Concomitantly, an increase of the molar ratio of cholesterol to phospholipids was observed with advanced age. The membrane viscosity as measured by 1,6 diphenyl‐1,3,5‐hexatriene increased with advanced age. These results indicate that the altered cholesterol content and/or viscosity in cortical membranes of the aged rat may account for the loss of α 1 ‐adrenergic receptor density and/or compensatory changes in the receptor‐phospholipase C coupling system.