Fig. 8.
The effect of systemic administration of TFMPP on light-induced phase delays of the circadian rhythm of wheel-running activity in wild-type and 5-HT1B receptor knock-out (KO) mice is illustrated in representative actograms. Mice were maintained in DD throughout the experiment and received injections of vehicle (top) or TFMPP (25 mg/kg, i.p.) (bottom) at CT 15.5 followed by light exposure (10 min at 20 lux) at CT 16 to elicit phase delays. TFMPP reduced light-induced phase shifts in wild-type mice (left) but had little effect in the 5-HT1B receptor knock-out mouse (right). The approximate time of light stimulation is indicated by the inverted triangles.