Central afferent pathways conveying nociceptive input to the hypothalamic paraventricular nucleus as revealed by a combination of retrograde labeling and c-fos activation

• Type: Article in International Scientific Journal
• Date: 1999

Authors

Pan, B (Author) Other; Castro-Lopes J.M. (Author) FMUP; Coimbra, A (Author) Other

Journal

Title: Journal of Comparative Neurology

Vol. 413

Pages: 129-145

ISSN: 0021-9967

Publisher: Wiley-Blackwell

Indexing

ISI Web of Knowledge - 35 Citations

Scopus - 42 Citations

Other information

Authenticus ID: P-001-335

DOI: 10.1002/(sici)1096-9861(19991011)413:1<129::aid-cne9>3.0.co;2-q

Abstract (EN): Previous data have shown that noxious thermal stimulation of the hind leg in the anesthetized rat causes c-fos activation in the paraventricular nucleus of the hypothalamus (PVN); in other brain nuclei, including the cathecholaminergic cell groups of the caudal medulla; and in the adenohypophysis. Stimulation was followed by adrenocorticotropic hormone plasma release but did not provoke cardiovascular changes. In the current study, the afferent central pathways conveying the nociceptive input to the PVN were studied throughout the brain by using double labeling for the Fos-protein and the retrograde tracer cholera toxin subunit B (CTb) injected into the PVN. Although double labeling occurred in several hypothalamic nuclei, the periaqueductal gray, the lateral parabrachial area, and the catecholaminergic medullary groups, high rates of double labeling occurred only in the cells of the Al region of the ventrolateral medulla (approximate to 83% of CTb-labeled cells expressing c-fos). Further triple labeling with tyrosine hydroxylase (TH) revealed that >80% of the double-labeled cells were TH-immunoreactive. The spinal cord had the usual strong c-fos expression but showed no retrograde labeling from the PVN. Noxious stimulation caused corticosterone plasma release. To ascertain a possible link of spinofugal neurons with the Al cells, biotinylated dextran amine was injected into the spinal dorsal horn. Numerous anterogradely labeled fibers with bouton-like structures were observed, with the latter apposed to double- and triple-labeled cells in the Al region. It is suggested that a dysynaptic route relayed in the Al region conveys the nociceptive somatic input from the spinal cord to the PVN. Noxious stimulation may act as a systemic stressor, activating the hypothalamic-pituitary-adrenal axis. J. Comp. Neurol. 413:129-145, 1999. (C) 1999 Wiley-Liss, Inc.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 17