Local sympathectomy was achieved by injecting 6-hydroxydopamine into the dermis at two sites on the right midside of each of three Merino wethers. Saline was injected into matching sites on the left midside. After one week, noradrenaline was injected into one site on each side and saline into the other. Colchicine was administered into all sites immediately after noradrenaline, skin biopsies removed from each site two hours later and histological preparations assessed for the accumulation of mitoses in wool follicles. Compared with saline treated sites, noradrenaline significantly depressed the number of accumulated mitoses at control and sympathectomised sites by 34 and 36% respectively (P=0.002). A pharmacological dose of noradrenaline therefore has the potential to reduce wool production. Sympathectomy increased mitotic rate at saline and noradrenaline treated sites by 16 and 18% respectively, although this increase was not significant at the 5% level (P=0.0094). Elevation of mitotic activity via elimination of endogenous sources of noradrenaline may help to explain the mechanism by which surgical sympathectomy has previously been reported to increase wool production.

GC, Upreti, J Oliver, R Munday, and JF Smith

Proceedings of the New Zealand Society of Animal Production, Volume 52, , 251-254, 1992
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