The caudal medullary ventrolateral reticular formation in nociceptive-cardiovascular integration. An experimental study in the rat

• Type: Article in International Scientific Journal
• Date: 2002

Authors

Deolinda Lima (Author) FMUP; Albino Teixeira, A (Author) FMUP; Isaura Tavares (Author) FMUP

Journal

Title: Experimental Physiology

Vol. 87

Pages: 267-274

ISSN: 0958-0670

Publisher: Wiley-Blackwell

Indexing

ISI Web of Knowledge - 27 Citations

Scopus - 36 Citations

Other information

Authenticus ID: P-000-Q42

DOI: 10.1113/eph8702354

Abstract (EN): The endogenous pain control system is composed of multiple functionally distinct brain regions, which are thought to integrate nociceptive information with various brain functions. The clear involvement of some pain control centres in cardiovascular modulation has been claimed as a strong indication of their role in nociceptive-cardiovascular integration. Particular emphasis has been given to their putative function in triggering cardiovascular reactions to pain. However, the possibility of their participation in the less-studied influence of cardiovascular conditions in pain perception has been largely ignored. We have recently addressed this issue by investigating the involvement of the caudal ventrolateral medullary reticular formation (cVLM) in hypertension-induced hypoalgesia. Circuits capable of conveying cVLM-elicited antinociception include a direct reciprocal cVLM-spinal loop, and two disynaptic spinal pathways relaying in rostroventromedial medullary (RVM) neurones and A(5) noradrenergic neurones. In the three pathways, the cVLM neurones involved are circumscribed to a small area of reticular formation located laterally to the lateral reticular nucleus, the VLMlat. The VLMlat has a vasodepressor effect similar to that obtained from the cVLM. In the spinal cord dorsal horn, c-fos expression evoked by noxious stimuli is decreased in hypertensive animals, as compared to normotensive animals. In hypertensive animals following lesion of the VLMlat, spinal c-fos expression is identical to that observed in normotensive animals. The collected data point to a role for the VLMlat in the depression of spinal nociceptive processing in response to rises in blood pressure. Since hypertension-induced hypoalgesia is mediated by spinal alpha(2)-adrenoreceptors, this effect could be conveyed by the cVLM-A(5)-spinal pathway.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8