The actions of capsaicin applied topically to the skin of the rat on C‐fibre afferents, antidromic vasodilatation and substance P levels

British Journal of Pharmacology - Tập 107 Số 2 - Trang 400-406 - 1992
Lynn Bry1,2, W. Ye1,2, B. Cotsell2
1Department of Biology, Shanghai Teacher's University, Shanghai 200234, China.
2Department of Physiology, University College London, Gower Street, London WC1E 6BT

Tóm tắt

Single applications of solutions of capsaicin were made to the intact skin of anaesthetized rats and the effects on cutaneous blood flow and the firing of C‐nociceptor afferents determined. Blood flow was measured by laser‐Doppler flowmetry. C‐fibre activity was recorded from filaments dissected from the saphenous nerve. Following the application of a capsaicin solution (concentration ≥ 1 mm) to rat saphenous skin, low frequency firing occurred in C‐polymodal nociceptors that sometimes continued for > 10 min. At the some time, large increases in skin blood flow occurred exceeding 300% in some instances. After the initial excitation, some C‐polymodal nociceptors lost their sensitivity to pressure whilst their sensitivity to heat was lost or enhanced depending on the vehicle used. Sensitivity of C‐polymodal nociceptors to heat recovered in > 1 day following a single application of 33 mm capsaicin. Thresholds to mechanical pressure, however, were still significantly elevated by 123% on day 1, but had recovered on day 2. Vasodilatation in response to saphenous nerve stimulation (‘antidromic vasodilatation’) was significantly reduced by 35%, 2 days after a single application of 33 mm capsaicin, but was normal at 4 days.6 Following a single application of 33 mm capsaicin, skin substance P levels fell to only half the normal value at day 1 and remained at this level throughout the 4 day period examined.7 It is suggested that the ability of relatively low concentrations of capsaicin to desensitize C‐fibre nociceptors may underlie the analgesic action of topical capsaicin in man.

Từ khóa


Tài liệu tham khảo

10.1073/pnas.80.2.594

10.1152/jn.1991.66.1.212

10.1016/S0190-9622(89)70171-7

10.1111/1523-1747.ep12520912

10.1016/0165-6147(90)90237-3

10.1111/j.1476-5381.1981.tb16812.x

10.1016/0304-3940(91)90890-6

10.1111/j.1748-1716.1953.tb01032.x

10.1016/0306-4522(88)90064-4

HOLZER P., 1991, Capsaicin: cellular targets, mechanisms of action, and selectivity for thin sensory neurones, Pharmacol. Rev., 43, 143

JANSCO N., 1968, Pharmacology of Pain, 35

10.1113/jphysiol.1989.sp017732

10.1016/0304-3940(82)90369-X

KOLTZENBERG M., 1991, Mechanically insensitive unmyelinated afferents supplying the hairy skin of the rat in vitro, J. Physiol., 438, 164P

10.1016/0306-4565(83)90107-9

10.1152/jn.1991.66.1.190

10.1007/BF00500282

10.1159/000210778

10.1159/000211010

10.1016/0006-8993(82)90768-5

LYNN B., 1992, Action of topical capsaicin on blood flow and C‐fibre nociceptors in the skin of anaesthetized rats, Br. J. Pharmacol., 105, 131P

10.1016/0304-3940(92)90415-4

10.1016/0306-4522(88)90065-6

10.1007/BF01965019

LYNN B., 1991, The effect of topical capsaicin on the sensitivity to mechanical and heat stimulation of C‐polymodal nociceptors in the skin of the anaesthetized rat, J. Physiol., 438, 164P

10.1016/0306-4522(89)90019-5

10.1016/0304-3959(91)90101-3

10.1111/j.1460-9568.1991.tb00089.x

10.1111/j.1460-9568.1990.tb00384.x

SCHEUPLEIN R.J., 1983, Biochemistry and Physiology of the Skin, 1255

10.1016/0304-3959(91)90217-L

10.1113/jphysiol.1987.sp016598

WOOD J.N., 1988, Capsaicin‐induced ion fluxes in dorsal root ganglion cells in culture, J. Neuroscience, 8, 3207

Thông tin
Thông tin xuất bản

British Journal of Pharmacology

Tập 107 Số 2

400-406

Thông tin tác giả