Chemical sensory deafferentation abolishes hypothalamic pituitary activation induced by noxious stimulation or electroacupuncture but only decreases that caused by immobilization stress. A c-fos study

• Type: Article in International Scientific Journal
• Date: 1997

Authors

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

Journal

Title: Neuroscience

Vol. 78

Pages: 1059-1068

ISSN: 0306-4522

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 39 Citations

Scopus - 39 Citations

Other information

Authenticus ID: P-001-BC3

DOI: 10.1016/s0306-4522(96)00661-6

Abstract (EN): We have shown in previous c-fos studies that noxious stimulation or electroacupuncture in deeply anaesthetized rats activate the hypothalamic-pituitary corticotrope axis in a specific way. C-Sos expression was more pronounced in the arcuate than the paraventricular hypothalamic nuclei, and none occurred in the pituitary intermediate lobe. The absence of the usual autonomic responses to psychological stress, such as tachycardia or blood pressure elevation, suggested a specific action of the somatosensory input on the hypothalamic-pituitary axis. To prove this hypothesis, c-fos expression was examined in the paraventricular, arcuate and other hypothalamic nuclei, the pituitary gland, and the Al and A2 medullary catecholaminergic cell groups of animals deprived of nociceptive primary afferent input by neonatal capsaicin. After noxious stimulation or electroacupuncture, no c-fos enhancement occurred in any of those sites in capsaicin-treated animals, and there was no increased plasma release of adrenocorticotropic hormone. In contrast, the hypothalamic-pituitary c-fos activation provoked by immobilization stress though markedly decreased, was not abolished by capsaicin, whereas plasma release of adrenocorticotropic hormone remained undiminished. These findings suggest that noxious stimulation or electroacupuncture act on the hypothalamic-pituitary corticotrope axis through an exclusively physical effect depending on the noxious signal elicited in the somatosensory pathway. They also demonstrate the occurrence of a minor somatosensory physical component after forced immobilization, acting on the hypothalamic-pituitary axis probably together with the prevalent component of emotional arousal elicited by this form of stress. (C) 1997 IBRO. Published by Elsevier Science Ltd.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10