Activation of EP4 receptors contributes to prostaglandin E2-mediated stimulation of renal sensory nerves.
Induction of cyclooxygenase-2 (COX-2) in the renal pelvic wall increases prostaglandin E(2) (PGE(2)) leading to stimulation of cAMP production, which results in substance P (SP) release and activation of renal mechanosensory nerves. The subtype of PGE receptors involved, EP2 and/or EP4, was studied by immunohistochemistry and renal pelvic administration of agonists and antagonists of EP2 and EP4 receptors. EP4 receptor-like immunoreactivity (LI) was colocalized with calcitonin gene-related peptide (CGRP)-LI in dorsal root ganglia (DRGs) at Th(9)-L(1) and in nerve terminals in the renal pelvic wall. Th(9)-L(1) DRG neurons also contained EP3 receptor-LI and COX-2-LI, each of which was colocalized with CGRP-LI in some neurons. No renal pelvic nerves contained EP3 receptor-LI and only very few nerves COX-2-LI. The EP1/EP2 receptor antagonist AH-6809 (20 microM) had no effect on SP release produced by PGE(2) (0.14 microM) from an isolated rat renal pelvic wall preparation. However, the EP4 receptor antagonist L-161,982 (10 microM) blocked the SP release produced by the EP2/EP4 receptor agonist butaprost (10 microM) 12 +/- 2 vs. 2 +/- 1 and PGE(2), 9 +/- 1 vs. 1 +/- 0 pg/min. The SP release by butaprost and PGE(2) was similarly blocked by the EP4 receptor antagonist AH-23848 (30 microM). In anesthetized rats, the afferent renal nerve activity (ARNA) responses to butaprost 700 +/- 100 and PGE(2).780 +/- 100%.s (area under the curve of ARNA vs. time) were unaffected by renal pelvic perfusion with AH-6809. However, 1 microM L-161,982 and 10 microM AH-23848 blocked the ARNA responses to butaprost by 94 +/- 5 and 78 +/- 10%, respectively, and to PGE(2) by 74 +/- 16 and 74 +/- 11%, respectively. L-161,982 also blocked the ARNA response to increasing renal pelvic pressure 10 mmHg, 85 +/- 5%. In conclusion, PGE(2) increases renal pelvic release of SP and ARNA by activating EP4 receptors on renal sensory nerve fibers.
Department of Internal Medicine, Department of Veterans Affairs Medical Center and University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA. ulla-kopp@uiowa.edu
Ulla C
UC
Kopp
Michael Z
MZ
Cicha
Kazuhiro
K
Nakamura
Rolf M
RM
Nüsing
Lori A
LA
Smith
Tomas
T
Hökfelt
D000344:Afferent Pathways / Q000187:drug effects* / Q000502:physiology; D000527:Alprostadil / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000032:analysis; D000242:Cyclic AMP / Q000096:biosynthesis; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000494:pharmacology*; D005455:Fluorescent Antibody Technique; D005727:Ganglia, Spinal / Q000737:chemistry; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000032:analysis; D007668:Kidney / Q000737:chemistry / Q000294:innervation*; D008297:Male; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis; D011459:Prostaglandins E, Synthetic; D051381:Rats; D017207:Rats, Sprague-Dawley; D018078:Receptors, Prostaglandin E / Q000032:analysis / Q000037:antagonists & inhibitors / Q000502:physiology*; D058306:Receptors, Prostaglandin E, EP1 Subtype; D058307:Receptors, Prostaglandin E, EP2 Subtype; D058309:Receptors, Prostaglandin E, EP4 Subtype; D013373:Substance P / Q000378:metabolism
D007527:Isoenzymes; D011459:Prostaglandins E, Synthetic; C545637:Ptger1 protein, rat; C545646:Ptger2 protein, rat; C545652:Ptger4 protein, rat; D018078:Receptors, Prostaglandin E; D058306:Receptors, Prostaglandin E, EP1 Subtype; D058307:Receptors, Prostaglandin E, EP2 Subtype; D058309:Receptors, Prostaglandin E, EP4 Subtype; D013373:Substance P; D000242:Cyclic AMP; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D000527:Alprostadil; C048491:butaprost; D015740:Calcitonin Gene-Related Peptide; D015232:Dinoprostone