Stimulation of locomotion in neonate rats by TRH analogue CG3703

Thyrotropin releasing hormone (TRH) and its analogues have been shown to depolarise motoneurons and stimulate cyclical motor activities such as respiration and locomotion. It has been suggested that one of its roles might be modulation of neuronal membrane excitability to release intrinsic rhythmicity. The present experiments were designed to determine whether it would initiate locomotion in the neonate rat prior to the development of spontaneous walking. It was found that the TRH analogue CG3703 did activate locomotion in 3-day-old rat pups. Quantification of various gait parameters and study of spatiotemporal footfall patterns showed the gait to be indistinguishable from the spontaneous locomotion of older pups. Possible loci of action are discussed.