Effects of a thyrotropin releasing hormone analogue on locomotor and other motor activity in the rat.

In the present experiments, locomotion has been studied in rats after injection of TRH analogue RX77368 (10 mg/kg i.p.). The measure used was the frequency of the cyclic shifts of weight from side to side (WTF) which accompany the progress of locomotion. It therefore provides an indirect measure of stepping frequency. After injection of RX77368 there was a shift in WTFs towards higher frequencies, i.e. when the rat walked it was taking more steps per second. These results suggest that RX77368 stimulates basic motor patterns associated with locomotion. The results obtained in these experiments are compared with those obtained using different quantification methods for locomotion and there is speculation concerning the possible modes of action of RX77368 including interactions with other neurotransmitter systems.