THYROTROPIN-RELEASING-HORMONE (TRH) NEURONS SPROUT IN CERVICAL SPINAL-CORD OF WOBBLER MOUSE

The present study was undertaken to quantify the immunocytochemical ch anges for thyrotropin-releasing hormone (TRH) within the ventral horn of the cervical spinal cord from Wobbler (wr/wr) mice selected at post natal ages 3 weeks to 5 months compared with the normal phenotype (NFR /wr) littermates as well as mice from two related normal mouse strains : the NFR/N parent strain, and the closely related C57Bl/6N mouse stra in. The immunoreactive (IR) neuronal processes containing TRH appeared in all specimens within Rexed's laminae VIII, IX, and X. Compared wit h the normal (C57Bl/6N, NFR/N) specimens, the pair-matched normal phen otype (NFR/wr) and Wobbler (wr/wr) specimens possessed significantly g reater numbers of IR-TRH containing processes at every age studied. Co mpared with the normal phenotype (NFR/wr) specimens, greater numbers o f IR-TRH containing processes appeared in the ventral horn region stud ied from the Wobbler (wr/wr) specimens taken early (Stage 1) as well a s later (Stages 3 and 4) in the motoneuron disease. An age-related dec line in the number of IR-TRH processes was apparent among the specimen s from the Wobbler mouse strain (NFR/wr, wr/wr), but not the normal (N FR/N, C57Bl/6N) mouse strains. The data suggest that TRH may play a si gnificant role in the Wobbler disease, possibly even before the sympto ms become apparent. In addition strain-related differences exist which may be important to the etiology of the Wobbler disorder.