Responses induced by acetylcholine, glutamic acid and serotonin in Xenopus laevis oocytes injected with mRNA of aged rat cortex

Poly (A)+mRNAs isolated from the cerebral cortex of the aged(32 months)and adult (3months)rats by acid guanidinum thiocyanate-phenol-chloroform(AGPC) method and Promegasnew magesphere technique were microinjected intoXenopus laevis oocytes to express functional neu-rotransmitter receptors.Electrophysiological record-ings of the membrane responses were used as a meas-ure of relative amounts of mRNA encoding differentreceptors to study the change of neurotransmitterreceptors of the aged rat brain The amplitude and 50% decay of depolarizationinduced by acetylcholine. glutamic acid and serotoninwere decreased and the latent periodand rise time ofdepolarization were increased These Parameters weresignifieantly different from the values obtained from the ooeytes injeeted with mRNA of the adult rat cortex The amplitudes of depolarization indueed by aeetyleholine glutamie aeid and serotonin were about 40%～60% of the adult control group and the tendencyof the changes in these receptors was similar to that ofthe aged rats. It is reasonable to estimate that the reduction ofneurotransmitter responses is due to the alteration inthe templet of receptor protein synthesis of the agcdrat brain