Effect of intravenous lidocaine administration on laminar inflammation in the black walnut extract model of laminitis.
BACKGROUND
Laminitis is a serious complication of horses suffering from sepsis/endotoxaemia-related events. Laminitis in horses and organ injury in human sepsis are both reported to involve inflammatory injury to the laminae/organs including early activation of endothelium and leucocytes leading to emigration of neutrophils into the tissue interstitium. In the black walnut extract (BWE) model, systemic inflammatory events coincide with marked increase in laminar mRNA concentrations of inflammatory genes including proinflammatory cytokines (i.e. IL-1beta, IL-6), COX-2, chemokines (i.e. IL-8) and endothelial adhesion molecules (i.e. ICAM-1 and E-selectin). In models of human sepsis, i.v. lidocaine has been reported to decrease leucocyte and endothelial activation, and the expression of proinflammatory cytokines and chemokines.


OBJECTIVE
To evaluate the effect of i.v. lidocaine therapy on the inflammatory processes documented to occur in the BWE model of laminitis.


METHODS
Twelve horses were administered BWE and treated immediately with either lidocaine (1.3 mg/kg bwt bolus, followed by 0.05 mg/kg bwt/min CRI, n=6) or saline (n=6) for 10 h. At 10 h post BWE administration, laminar samples were obtained under general anaesthesia for assessment of proinflammatory gene expression (using RT-qPCR) and leucocyte emigration (via CD13 immunohistochemistry). At 0, 3 and 10 h post BWE administration, skin samples were obtained for assessment of leucocyte emigration (via calprotectin immunohistochemistry).


RESULTS
No significant differences between groups were noted for inflammatory gene mRNA concentrations (IL-1beta, IL-6, IL-8, COX-2) or for number of leucocytes present within the laminar interstitium or skin dermis. Increased (P<0.05) laminar E-selectin mRNA concentrations were present in the LD group (vs. SAL group).


CONCLUSIONS
Continuous administration of i.v. lidocaine does not inhibit inflammatory events in either the laminae or skin in the horse administered black walnut extract.


CONCLUSIONS
This work questions the use of continuous i.v. administration of lidocaine as an effective anti-inflammatory therapy for systemic inflammation.
Williams
J M
JM
Department of Clinical Sciences, The Ohio State University, College of Veterinary Medicine, Columbus, OH 43210, USA.
Lin
Y J
YJ
Loftus
J P
JP
Faleiros
R R
RR
Peroni
J F
JF
Hubbell
J A E
JA
Ravis
W R
WR
Belknap
J K
JK
D000779:Anesthetics, Local / Q000008:administration & dosage / Q000627:therapeutic use; D000818:Animals; D005534:Foot Diseases / Q000139:chemically induced / Q000188:drug therapy / Q000662:veterinary*; D006724:Hoof and Claw; D006734:Horse Diseases / Q000139:chemically induced* / Q000188:drug therapy; D006736:Horses; D007249:Inflammation / Q000139:chemically induced / Q000188:drug therapy / Q000662:veterinary*; D031324:Juglans / Q000737:chemistry; D008012:Lidocaine / Q000008:administration & dosage* / Q000627:therapeutic use*; D010936:Plant Extracts / Q000737:chemistry / Q000633:toxicity; D014934:Wood / Q000737:chemistry
D000779:Anesthetics, Local; D010936:Plant Extracts; D008012:Lidocaine