GABA-sensitivity of dorsal column axons: an in vitro comparison between adult and neonatal rat spinal cords.
In neonatal rat spinal cord, conduction in the dorsal column is reversibly depressed by GABA. We compared the GABA-sensitivity of dorsal columns in neonate versus adult rats, using in vitro isolated dorsal column preparations. The extracellular compound action potential evoked by submaximal stimuli was recorded with a glass micropipette. GABA (10(-4)-10(-3) M) reversibly depressed the compound action potential of both neonatal and adult rat dorsal columns. The GABA-induced reduction of dorsal column compound action potential amplitudes was blocked by the GABAA antagonist picrotoxin (10(-3) M) and mimicked by the GABAA agonist isoguvacine (10(-4-10(-3) M). The compound action potential reduction by GABA was far less pronounced on adult dorsal columns. The reduction of compound action potential amplitudes by isoguvacine (10(-4)-10(-3) M) was also significantly less in adult dorsal columns. These data suggest that GABAA receptors may play a role in extrasynaptic modulation of spinal long tract conduction in an age-dependent manner.
Sakatani
K
K
Department of Neurosurgery, New York University Medical Center, NY 10016.
Hassan
A Z
AZ
Chesler
M
M
D000200:Action Potentials / Q000187:drug effects; D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D001369:Axons / Q000187:drug effects / Q000502:physiology*; D007539:Isonicotinic Acids / Q000494:pharmacology; D009431:Neural Conduction / Q000187:drug effects*; D051381:Rats; D011963:Receptors, GABA-A / Q000187:drug effects / Q000502:physiology; D013116:Spinal Cord / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D007539:Isonicotinic Acids; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; C015300:isoguvacine