Investigation of the effect of black walnut extract on in vitro ion transport and structure of equine colonic mucosa.
OBJECTIVE
To examine the secretory response (in the presence and absence of prostaglandin inhibition) in vitro and structural alterations of colonic mucosa in horses after intragastric administration of black walnut extract (BWE).


METHODS
14 adult horses.


METHODS
Seven horses were administered BWE intragastrically and monitored for 11 hours. Tissue samples were obtained from the right ventral, left ventral, and right dorsal colons (RVC, LVC, and RDC, respectively) of the 7 BWE-treated and 7 control horses. Tissue samples were examined via light microscopy, and the extent of hemorrhage, edema, and granulocytic cellular infiltration (neutrophils and eosinophils) was graded. Colonic mucosal segments were incubated with or without flunixin meglumine (FLM) for 240 minutes; spontaneous electrical potential difference and short-circuit current (Isc) were recorded and used to calculate mucosal resistance.


RESULTS
Colonic tissues from BWE-treated horses (with or without FLM exposure) had an overall greater Isc during the 240-minute incubation period, compared with tissues from control horses. The resistance pattern in RVC, LVC, and RDC samples (with or without FLM exposure) from BWE-treated horses was decreased overall, compared with control tissues (with or without FLM exposure). Histologically, colonic mucosal tissues from BWE-treated horses had more severe inflammation (involving primarily eosinophils), edema, and hemorrhage, compared with tissue from control horses.


CONCLUSIONS
In horses, BWE administration appears to cause an inflammatory response in colonic mucosal epithelium that results in mucosal barrier compromise as indicated by decreased mucosal resistance with presumed concomitant electrogenic chloride secretory response, which is not associated with prostaglandin mediation.
McConnico
Rebecca S
RS
Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA.
Stokes
Ashley M
AM
Eades
Susan C
SC
Moore
Rustin M
RM
D000704:Analysis of Variance; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D001774:Blood Chemical Analysis / Q000662:veterinary; D001831:Body Temperature / Q000187:drug effects; D003002:Clonixin / Q000031:analogs & derivatives* / Q000494:pharmacology; D003106:Colon / Q000187:drug effects* / Q000473:pathology; D005528:Foot / Q000473:pathology*; D006339:Heart Rate / Q000187:drug effects; D006652:Histological Techniques / Q000662:veterinary; D006736:Horses / Q000502:physiology*; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000473:pathology; D017136:Ion Transport / Q000187:drug effects; D031324:Juglans / Q000737:chemistry*; D010936:Plant Extracts / Q000633:toxicity; D011448:Prostaglandin Antagonists / Q000494:pharmacology; D015656:Respiratory Mechanics / Q000187:drug effects; D013997:Time Factors
D010936:Plant Extracts; D011448:Prostaglandin Antagonists; C014558:flunixin meglumine; D003002:Clonixin