Figure 3. Cycle frequency of rhythmic trigeminal motor activities in minimum and whole blocks. (A) Rhythmic trigeminal motor activity was induced by an application of 5-HT (60 µM), 5-HT_2C receptor agonist (DOI, 20 µM), 5-HT_1A receptor antagonist (NAN190, 20 µM), and those in combination with BIC (10 µM) - NMA (20 µM) in whole brainstem preparations. Furthermore, it was also induced by BIC (10 µM) - NMA (20 µM) stimulation alone, whereas inhibition was not recognized in the minimum preparations. (B) Bar graphs indicate the cycle frequency of rhythmic trigeminal motor activities in the minimum and whole brainstem preparations as induced by 5-HT (60 µM) and those related agents (DOI, 20 µM; NAN190, 20 µM) with BIC (10 µM) - NMA (20 µM), respectively. Control: Cycle frequency of trigeminal rhythmic activities induced by BIC-NMA in the minimum brainstem blocks. In the whole brainstem, the rhythm induced by 5-HT and related agents was slower than in the control, whereas when these were applied to the minimum brainstem preparations, the rhythm was not significantly different from that of the control. *: significantly different from control (p < 0.01). Whole block: 5-HT (n = 9), DOI (n = 4), NAN190 (n = 6). Minimum block: Control (n = 8), 5-HT (n = 7), DOI (n = 14), NAN190 (n = 14).