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GABA-sensitivity of dorsal column axons: an in vitro comparison between adult and neonatal rat spinal cords

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Abstract

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.

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  • Beyond faithful conduction: Short-term dynamics, neuromodulation, and long-term regulation of spike propagation in the axon

    2011, Progress in Neurobiology
    Citation Excerpt :

    Experiments with re-uptake inhibitors suggest that there is an endogenous source of GABA (Sakatani et al., 1993). GABA sensitivity is still present in adult rats, albeit far less pronounced (Sakatani et al., 1991b), suggesting a predominantly developmental role. It remains unclear, at least in the adult, what the source of GABA may be, and if it plays a functional role in the adult animal (Kocsis and Sakatani, 1995).

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