Thyrotropin-releasing hormone (TRH) degradation in NIH:N mouse cerebral cortex and spinal cord

Thyrotropin-releasing hormone (TRH) metabolism in NIH:N mouse cerebral cortex and spinal cord was studied with high pressure liquid chromatography. Degradation of added TRH was significantly (P less than 0.001) slower in the spinal cord (2.19 +/- 0.46%/min) than in the cerebral cortex (7.54 +/- 0.31%/min). Bacitracin, a non-competitive inhibitor of TRH deamidase, inhibited TRH degradation by 61.3 +/- 3.7% in the spinal cord but only by 35.9 +/- 1.0% in the cerebral cortex (P less than 0.001). Catabolism of TRH in the mouse spinal cord proceeds at a slower rate and predominantly via the TRH deamidase pathway.