KCl-induced repetitive cortical spreading depression inhibiting trigeminal neuronal firing is mediated by 5-HT
1B/1D and opioid receptors.
Cephalalgia 2022;
42:1339-1348. [PMID:
35833238 PMCID:
PMC9638706 DOI:
10.1177/03331024221112998]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Background
We aimed to examine the effects of repetitive cortical spreading depression
on the responses of nociceptive trigeminal neurons with dural afferents and
characterize the role of 5-HT1B/1D and opioid receptors.
Methods
Trigeminocervical complex neurons (n = 53) responsive to
nociceptive activation of the dura mater were studied in rats using
electrophysiological techniques.
Results
A sub-population (n = 32) showed an average inhibition of
dural-evoked responses of 65 ± 14% from baseline with cortical spreading
depression. This response was reversed by the selective 5-HT1B/1D
receptor antagonist, GR127935 (3 mg/kg; n = 6, iv), and a
non-selective opioid receptor antagonist, naloxone (1.5 mg/kg;
n = 6, iv), five minutes after injection. To determine
the role of the nucleus raphe magnus in the trigeminocervical complex
inhibitory effect, microinjection of lidocaine (2%, n = 6)
or muscimol (100 mM, n = 5) into the nucleus raphe magnus
was performed. There was no effect on cortical spreading depression-induced
inhibition of neuronal firing in trigeminocervical complex by either.
Conclusion
The data demonstrate that repetitive cortical spreading depression inhibits a
subpopulation of dural nociceptive trigeminocervical neurons, an effect
mediated by serotonin and opioid receptors. This inhibition does not involve
modulation of nucleus raphe magnus neurons.
Collapse