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

Abstract

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. The levels fluctuated substantially in the cervical spinal cord. During the first 3 days of the estrous cycle, the substance P and neurokinin A contents fell concomitant with the 17β‐estradiol surge, suggesting a downregulation of substance P and neurokinin A contents by 17β‐estradiol. Furthermore, on estrus, progesterone seemed to inhibit the accumulation of both neurokinins. Testosterone may stimulate accumulation of substance P and neurokinin A in the cervical spinal cord, with a marked circadian rhythm. These results are in favor of the neurokinin content of the spinal cord being regulated by the gonadal steroids. In the trigeminal nucleus, only testosterone has an effect. © 1996 Wiley‐Liss, Inc.

Acute and Chronic Craniofacial Pain: Brainstem Mechanisms of Nociceptive Transmission and Neuroplasticity, and Their Clinical Correlates

“…Furthermore, antagonism of submeptor (NKI) mechanisms can block caudalis ,sion induced by noxious chemical stimula-1 afferents (Shepheard et al, 1995) (Bakke et al, 1998a). It is noteworthy that whereas substance P receptor processes, as well as NK2 receptor mechanisms (related to neurokinin A), predominate in caudal components of the VBSNC, it appears that other neuropeptides found in small-diameter afferents, such as calcitonin gene-related peptide (CGRP) and nerve growth factor, may be more widespread in the VBSNC Yoshida et al, 1991;BennettClarke and Chiaia, 1992;Stover et al, 1992;Yew et al, 1992;Brown et al, 1995;Duval et al, 1996;Henry et al, 1996;Quartu et al, 1996;Sugimoto et al, 1997a), although unfortunately not all neuropeptide-related studies of the VBSNC have carefully investigated regions rostral to subnucleus caudalis.…”

Trigeminal Electrophysiology: a 2 × 2 matrix model for differential diagnosis between temporomandibular disorders and orofacial pain

“…Substance P (SP) and neurokinin A (NKA) are found in the synovial fluid, nerve fibers of the temporomandibular joint (TMJ), and the subnucleus caudalis of the V cranial nerve [23]. Nociceptive stimuli cause SP and NKA release, thus facilitating nociceptive reactions through a slow depolarization mediated by the tachykinin receptors, or through the release of other substances such as excitatory amino acids.…”

Exacerbation d´un syndrome douloureux chronique diffus par l´introduction d´un inhibiteur de l´aromatase

“…Cette enzyme jouerait également un rôle direct dans le métabolisme de certains neurotransmetteurs. Les hormones sexuelles influencent aussi le taux de nombreux neuromodulateurs impliqués dans l'intégration nociceptive tels que la substance P [27,28], des acides aminés (GABA -gamma-aminobutyric acid, glutamate) et d'autres neurotransmetteurs comme la noradrénaline, la dopamine et la sérotonine [29]. De nombreuses études sur le rôle des hormones sexuelles dans la perception douloureuse et son intégration ont été réalisées chez l'animal mais les connaissances chez l'être humain sont lacunaires et contradictoires [19].…”