The effect of lesions of the dorsal acoustic stria on the levels of glutamic acid decarboxylase and GABA transaminase in the inferior colliculus and cochlear nucleus of the guinea-pig.
The levels of glutamic acid decarboxylase (GAD) and ?-amino butyric acid-?-oxoglutarate transaminase (GABA-T) have been investigated in the cochlear nucleus and inferior colliculus of the guinea-pig after hemilateral section of the dorsal acoustic stria. Animals were cerebellectomised and the stria on one side cut. Eleven days later the animals were killed and GAD and GABA-T assayed in the respective nuclei. There was no change in the enzyme levels of the inferior colliculi showing no direct GABA-ergic fibres ascending through the stria and terminating in the inferior colliculi. The levels of both GAD and GABA-T in the cochlear nucleus on the operated side decreased significantly. It is concluded that about 30% of the GAD containing terminals in the cochlear nucleus arise from fibres descending through the dorsal acoustic stria. The bulk of the GABA-ergic transmission in the cochlear nucleus is assumed to involve an intrinsic system of short axoned neurones, the majority of which have their nerve endings in the dorsal part of the nucleus.
Davies
W E
WE
Neurocommunications Research Unit, The University of Birmingham, Birmingham B15 2TJ, UK.