Downregulation of metabotropic glutamate receptor 1a in motoneurons after axotomy

Abstract

AXOTOMIZED motoneurons display drastic modifications in synaptic structure and function related to their disconnection from the periphery and establishment of a regenerative metabolic functional mode. The molecular basis of these modifications is not fully understood. Here we describe changes in metabotropic glutamate receptor 1a (mGluR1a)-immunoreactivity 3, 7 or 14 days after unilateral sciatic transection. mGluR1a-immunoreactivity was distributed throughout the somatic cytoplasm and somatodendritic membrane of uninjured motoneurons and was significantly reduced in axotomized motoneurons. This reduction was observed at 3 days and grew progressively over 2 weeks. These findings suggest that downregulation of mGluR1a could contribute to reduced excitatory neurotransmission in axotomized motoneurons.