TAC1 and subarachnoid hemorrhage: Peripheral nerve endings of TG neurons contain potent vasodilatory neuropeptides such as substance P, calcitonin gene-related peptide, neurokinin A, and pituitary adenylate-cyclase activating peptide, which can be released through an axon reflex and provide efferent potential in pathophysiologic setting such as subarachnoid hemorrhage [4].