TRANSGANGLIONIC EFFECT OF BASIC PEPTIDES ON THE PRIMARY NOCICEPTIVE ANALYZER

Abstract

Central terminals of primary nociceptive neurons are dependent on transganglionic regulation by nerve growth factor (NGF), supplied to dorsal root ganglion cells by means of retrograde axoplasmic transport. Whenever this transport is blocked, primary sensory central terminals undergo transganglionic degenerative atrophy (TDA). TDA is characterized by electron microscopic and histochemical alterations, resulting in impaired synaptic transmission of potentially painful impulses and in alleviation of chronic pain. On the basis of structural similarity between NGF and the cyclic basic peptides Polymyxin and Colistin, we studied the effects of basic peptides applied to peripheral nerves (in rats) or, by means of iontophoresis, to the skin (of patients). The histochemical alterations (TDA) as well as the alleviation of pain was comparable to that reported earlier after application of transport block or Vinca alkaloids. Since basic peptides do not block axoplasmic transport it is assumed that their effect is due to comparative antagonism or intramolecular interaction with NGF.