Age-related electrophysiological changes in rat cerebellum.
The spontaneous discharge of cerebellar Purkinje neurons was studied in 3-, 12-, 15-, and 20-month-old rats. Fluphenazine and haloperidol administered intraperitoneally produced a dose-dependent increase in the spontaneous discharge in 3-month-old animals, but were ineffective in 12-, 15- and 20-month-old rats. Intraperitoneal administration of amphetamine resulted in a dose-dependent decrease in spontaneous Purkinje neuron discharge in 3-month-old rats without affecting neurons from the older animals. Discrution of norepinephrine afferents by 6-OHDA or reserpine increased spontaneous discharge rate in 3-month-old animals. This treatment did not affect Purkinje neurons in 12-, 15- and 20-month-old rats. Local application of drug with the same multibarreled electrode revealed that neurons from older rats were significantly less sensitive to inhibition by norepinephrine than were Purkinje neurons from 3-month-old animals. Similar application of GABA did not reveal a differential sensitivity. For locus coeruleus activation to produce 50% inhibition in Purkinje neuron discharge, significantly higher stimulation currents were required in 15-month-old rats than in 3-month-old animals. Our results suggest a decreased postsynaptic sensitivity to norepinephrine in 12-, 15- and 20-month-old rats as compared to 3-month-old animals.
D000375:Aging; D000661:Amphetamine / Q000494:pharmacology; D000818:Animals; D002531:Cerebellum / Q000502:physiology*; D005476:Fluphenazine / Q000494:pharmacology; D006220:Haloperidol / Q000494:pharmacology; D008125:Locus Coeruleus / Q000502:physiology; D008297:Male; D009433:Neural Inhibition / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D011689:Purkinje Cells / Q000187:drug effects / Q000502:physiology; D051381:Rats; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D005680:gamma-Aminobutyric Acid; D000661:Amphetamine; D006220:Haloperidol; D005476:Fluphenazine; D009638:Norepinephrine