Marked increases in calcitonin gene-related peptide-containing nerves in the developing rat following long-term sympathectomy with guanethidine.
Changes in the innervation of the cardiovascular system, urinogenital tract and sympathetic and non-sympathetic ganglia have been examined following long-term sympathectomy. Patterns of innervation were investigated using histochemical and immunohistochemical techniques, while levels of noradrenaline and neuropeptides were measured by neurochemical assays. Large doses of guanethidine (50 mg/kg) were given daily for 3 weeks to 8-day-old rat pups, which were killed at 6 or 20 weeks of age. In both age groups noradrenergic nerves were severely depleted or absent, while in some regions dramatic increases of calcitonin gene-related peptide levels were demonstrated. This was revealed by an increase in the density of nerve fibres and in calcitonin gene-related peptide content (up to 18-fold), most notably in the right atrium and superior cervical ganglion. No changes in substance P- or vasoactive intestinal polypeptide-immunolabelled nerves were seen. Conversely, short-term sympathectomy by 6-hydroxy-dopamine treatment caused a depletion of noradrenaline which was not accompanied by an increase in the number or content of calcitonin gene-related peptide-immunolabelled nerves. The possibility that nerve growth factor is involved in the mechanism of hyperinnervation by calcitonin gene-related peptide-containing sensory nerves following long-term sympathectomy is discussed.
Aberdeen
J
J
Department of Anatomy and Developmental Biology, University College London, U.K.
Corr
L
L
Milner
P
P
Lincoln
J
J
Burnstock
G
G
D000320:Adrenergic Fibers / Q000502:physiology*; D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D002319:Cardiovascular System / Q000254:growth & development / Q000294:innervation*; D006145:Guanethidine; D006892:Hydroxydopamines; D007150:Immunohistochemistry; D009420:Nervous System / Q000254:growth & development / Q000378:metabolism*; D016627:Oxidopamine; D051381:Rats; D011919:Rats, Inbred Strains; D013563:Sympathectomy, Chemical; D014566:Urogenital System / Q000254:growth & development / Q000294:innervation*
D006892:Hydroxydopamines; D016627:Oxidopamine; D015740:Calcitonin Gene-Related Peptide; D006145:Guanethidine