Effects of spinal cord transection on synapse numbers and biochemical maturation in rat lumbar sympathetic ganglia.
The effects of interruption of descending central pathways on the morphological and biochemical ontogeny of peripheral sympathetic ganglia were examined in the sixth lumbar (L6) sympathetic rat ganglia. Previous studies defined the normal maturation of presynaptic choline acetyltransferase (CAT) activity, postsynaptic tyrosine hydroxylase (T-OH) activity, and total protein in the L6 ganglion. In the present investigations ganglion synapse numbers and adrenergic neuron numbers were examined in transected and sham-operated littermate controls 6 weeks after surgery at 10 days of age and correlative biochemical studies were performed. Spinal transection resulted in a reduction in synapse number on ganglion cell bodies (53.5% reduction) and neuronal processes (55.8% reduction). This abnormality in synapse number was associated with a reduction of CAT activity to 56% of control. Although T-OH activity also failed to develop normally and was 25% of control, there was no associated alteration in adrenergic neuron number. These studies suggest that descending central pathways regulate the maturation of presynaptic cholinergic terminals (and hence synapse number) in sympathetic ganglion and that CAT activity serves as an accurate marker for these terminals. Additionally, the ontogeny of ganglion T-OH activity is altered by central lesions and this effect is not secondary to a decrease in adrenergic neuron number.
D000818:Animals; D000831:Animals, Newborn; D002452:Cell Count; D002795:Choline O-Acetyltransferase / Q000378:metabolism*; D005728:Ganglia, Sympathetic / Q000166:cytology / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology; D009638:Norepinephrine / Q000378:metabolism; D051381:Rats; D013116:Spinal Cord / Q000502:physiology*; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
D014446:Tyrosine 3-Monooxygenase; D002795:Choline O-Acetyltransferase; D009638:Norepinephrine