EFFECTS OF DIABETES ON TISSUE CONTENT AND EVOKED RELEASE OF CALCITONIN-GENE-RELATED PEPTIDE-LIKE IMMUNOREACTIVITY FROM RAT SENSORY NERVES

We measured the evoked release of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) from sensory nerve terminals in tracheas f rom control and diabetic rats using an in vitro perfusion system and a lso the CGRP-LI content of the vagus nerve and trachea. Diabetes cause d a 29% (P < 0.05) reduction in CGRP-LI content of the vagus nerve and a decrease in CGRP-LI release from nerve endings in the trachea evoke d by either capsaicin (30% decrease, P < 0.05) or electrical field sti mulation (50% decrease: P < 0.05). In contrast, there was a 50% increa se in the CGRP-LI content of the unstimulated trachea. Thus, diabetes induces an impairment in neuropeptide release from peripheral terminal s of sensory nerves that corresponds to decreased levels in the supply ing nerve but is not reflected in tissue measurements that incorporate nerve terminals. Impaired neuropeptide release may contribute to peri pheral and central sensory dysfunction in diabetic rats. (C) 1998 Publ ished by Elsevier Science Ireland Ltd. All rights reserved.