Male RORγt-transgenic mice exhibit lower body weight and an altered locomotor response to a novel environment

ROR{gamma}t, encoded by Rorc, is a key transcriptional regulator of T helper 17 (Th17) cell differentiation, and IL-17A signaling has been implicated in neural development and behavior. We examined behavioral phenotypes in male ROR{gamma}t-transgenic mice with T-cell-biased ROR{gamma}t overexpression and their wild-type littermates. Mice were assessed using the resident-intruder paradigm and the light-dark box test, followed by body-weight measurement. ROR{gamma}t-transgenic mice had significantly lower body weight than wild-type mice. No genotype differences were detected in attack latency, attack frequency, light-compartment occupancy, light-dark transitions, or transition latency. In contrast, analysis of locomotor activity in 1-min bins revealed a significant genotype x time interaction. Transgenic mice showed nominally reduced locomotor activity during the first minute of the light-dark box test, although this single-bin comparison did not remain significant after correction for multiple comparisons. These findings indicate that T-cell-biased ROR{gamma}t overexpression is associated with altered temporal dynamics of locomotor activity in a novel environment rather than a generalized anxiety-like or aggression-related phenotype.