Noradrenergic innervation of rabbit pancreatic ganglia.
Sympathetic nerve stimulation indirectly regulates pancreatic endocrine and exocrine secretion, in part, through actions on the cholinergic parasympathetic innervation of the secretory tissues. Earlier work identified noradrenergic nerves in pancreatic ganglia and demonstrated the effects of exogenous norepinephrine (NE) on synaptic transmission but no quantitative studies of ganglionic NE content and release exist. Therefore, the distribution and density of catecholamine (CA)-containing nerves in rabbit pancreatic ganglia were studied using paraformaldehyde/glutaraldehyde (FAGLU) staining and HPLC analysis of CA concentrations. Neural release of [3H]NE was measured in ganglia isolated from the head/neck or body regions of the pancreas. CA-containing nerves densely innervated most ganglia (86%) from both regions, while neural and non-neural CA-containing cell bodies were rarely found. Ganglia from the head/neck region contained significantly higher concentrations of NE. Both 40 mM K+ and veratridine evoked Ca2+-dependent [3H]NE release and tetrodotoxin inhibited 80% of veratridine-stimulated release. omega-Conotoxin GVIA alone antagonized veratridine-stimulated release by 40% but the addition of nifedipine or omega-agatoxin IVA caused no further inhibition. There were no apparent regional differences in the Ca2+-dependence or toxin-sensitivity of NE release. In conclusion, ganglia throughout the rabbit pancreas receive a dense, functional noradrenergic innervation and NE release is dependent upon N- but not P/Q- or L-type voltage-dependent Ca2+ channels. These noradrenergic nerves may indirectly regulate pancreatic secretion through actions on ganglionic transmission.
Yi
Eunyoung
E
Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216-4505, United States.
Smith
Tina G
TG
Love
Jeffrey A
JA
D000704:Analysis of Variance; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004305:Dose-Response Relationship, Drug; D005260:Female; D005724:Ganglia / Q000187:drug effects / Q000378:metabolism*; D005728:Ganglia, Sympathetic / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D010179:Pancreas / Q000294:innervation*; D011189:Potassium Chloride / Q000494:pharmacology; D011817:Rabbits; D013779:Tetrodotoxin / Q000494:pharmacology; D014316:Tritium / Q000378:metabolism; D014701:Veratridine / Q000494:pharmacology
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D014316:Tritium; D013779:Tetrodotoxin; D011189:Potassium Chloride; D014701:Veratridine; D009638:Norepinephrine