densely packed immunoreactive fibers were widely distributed in the substantia nigra , nucleus interpeduncularis , nucleus raphes , superior colliculus , periaqueductal central gray , nucleus parabrachialis lateralis and medialis , locus coeruleus , trapezoid body , nuclei cochleares , nucleus spinalis nervi trigemini , tractus spinalis nervi trigemini , nucleus tractus solitarii , nucleus dorsalis nervi vagi , nucleus gracilis , nucleus cuneatus , nucleus cuneatus accessorius , and in the reticular formation throughout the lower brainstem .
C0023951
locus coeruleus
C0006121
brainstem