Electrophysiological phenomena recorded from spinal cord slice preparation in the adult rat

Abstract

The dorsal root potential (DRP-V) is believed to have the same origin as the slow positive potential of the segmental spinal cord potential. Furthermore it is also thought to be a reflection of primary afferent depolarization (PAD) which is an index of presynaptic inhibition1. It is believed that primary afferent terminals are depolarized by GABAergic neurons in the substantia gelatinosa (lamina-II). However, intracellular recording from substantia gelatinosa (SG) neurons has been impossible in vivo and very difficult in vitro, because of the high vulnerability of SG neurons to anoxic and mechanical damage in adult rat together with their small size. An in vitro spinal preparation has been developed in the newborn rat. However, it is known that the mode of synaptic transmissions in the adult rat is not the same as in the newborn rat2,3. We therefore developed an in vitro adult rat spinal cord slice preparation to achieve stable intracellular recordings from SG neurons simultaneously with electrotonic potentials from the dorsal root for studying the relationship between them.