Possible neurotransmitters of the dorsal column afferents: effects of dorsal column transection in the cat.
We investigated quantitative changes in markers of possible neurotransmitters in the dorsal column nuclei following transection of the dorsal column in the cat. Seven days after unilateral transection of the dorsal column at the upper cervical level, choline acetyltransferase activity and concentrations of glutamate, aspartate, gamma-aminobutyrate and substance P were measured throughout the longitudinal axis of the dorsal column nuclei. In addition, high-affinity uptake of choline, D-aspartate and gamma-aminobutyrate into the synaptosomal fraction of the dorsal column nuclei were also measured. Choline acetyltransferase activity and high-affinity choline uptake were reduced by approx. 30% on the caudal to the obex. Reduction of high-affinity uptake of D-aspartate by approx. 30% was observed on the operated side in the central part of these nuclei, although the decrease in glutamate and aspartate was not significant in the nuclei on the operated side compared with that on the intact side. No significant changes were found in the high-affinity uptake of gamma-aminobutyrate or the contents of gamma-aminobutyrate and substance P in any areas of the dorsal column nuclei. These results suggest that not only glutamate and/or aspartate but also acetylcholine may be neurotransmitter candidates for the ascending fibres terminating in the dorsal column nuclei, whereas there may be few fibres containing substance P or gamma-aminobutyrate in the dorsal column.
D000818:Animals; D001224:Aspartic Acid / Q000032:analysis / Q000378:metabolism; D002415:Cats; D002794:Choline / Q000378:metabolism; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D005971:Glutamates / Q000032:analysis / Q000378:metabolism; D018698:Glutamic Acid; D008526:Medulla Oblongata / Q000378:metabolism; D009475:Neurons, Afferent / Q000032:analysis*; D018377:Neurotransmitter Agents / Q000032:analysis*; D013116:Spinal Cord / Q000032:analysis* / Q000201:enzymology / Q000378:metabolism / Q000601:surgery; D013373:Substance P / Q000032:analysis / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000032:analysis / Q000378:metabolism
D005971:Glutamates; D018377:Neurotransmitter Agents; D001224:Aspartic Acid; D013373:Substance P; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D002795:Choline O-Acetyltransferase; D002794:Choline