Substance P and neurokinin A variations throughout the rat estrous cycle; comparison with ovariectomized and male rats: II. Trigeminal nucleus and cervical spinal cord

Substance P and neurokinin A were assayed in the trigeminal nucleus and cervical spinal cord of 4‐day cycling female, ovariectomized, and male rats. During the estrous cycle, levels were largely stable in the trigeminal nucleus. In ovariectomized rats, the levels differed from those on any day of the estrous cycle suggesting a weak effect of ovarian steroids. In males, the variations in the substance P and neurokinin A contents in the trigeminal nucleus were not similar to those in either cyclic or ovariectomized rats.