Figure 2. Effect of 5-HT agonist and antagonist in whole and medium blocks. (A) Application of 5-HT_2C receptor agonist (DOI, 20 µM) and 5-HT_1A receptor antagonist (NAN190, 20 µM) induced rhythmic trigeminal motor activity in the whole brainstem preparations, whereas application of the 5-HT_2BC,5 receptor antagonist (methysergide, 50 µM) and 5-HT_1A receptor agonist (8OH-DPAT, 50 µM) did not. (B) Application of the 5-HT_2C receptor agonist (DOI, 20 µM) and 5-HT_1A receptor antagonist (NAN190, 20 µM) induced rhythmic trigeminal motor activity in the brainstem preparations that contained the facial nucleus (medium block), whereas application of the 5-HT_2BC,5 receptor antagonist (methysergide, 50 µM) and 5-HT_1A receptor agonist (8OH-DPAT, 50 µM) did not. (C) A section that contained the facial nucleus (medium block) prepared after the end of an experiment. (Infra-red photograph of a sagittal section, 250 µ.)