Evaluation of early events in the creation of amyenteric opossum model of achalasia.
Benzyldimethyltetradecylammonium chloride (BAC) has previously been used to create amyenteric rat jejunal models. Fifteen opossums (D. virginiana) were injected with 10-15 mL 4 mM BAC or saline in the distal oesophagus and along with controls underwent oesophagoscopy, manometry and barium oesophagrams. Atropine and sodium nitroprusside were studied in six of the BAC-treated and five controls using oesophageal manometry. Histologically several neuronal markers, B-NADPH-diaphorase and acetylcholine esterase histochemical staining were used. NADPH-diaphorase activity was assayed at the lower oesophageal sphincter (LOS) and 3 and 5 cm above LOS in both groups. Oesophagoscopy of the treated animals showed no mucosal inflammation, or strictures. Manometrically, LOS pressures were significantly higher in the BAC-treated group (25.7 +/- 8.6 mmHg) when compared to controls (8.7 +/- 1.8 mmHg). The oesophageal contraction amplitudes were similar in both groups. While sodium nitroprusside (SNP) significantly reduced the LOS pressure, atropine did not alter the resting LOS pressure in the BAC-treated animals. Histologically at the LOS the treated group showed: (i) absence of myenteric neurons, in contrast to prominent NADPH-diaphorase and other neuron and peptide markers in the control and (ii) increase in the number of nerve bundles that were not positive for AchE. No differences were seen in the oesophageal body between the groups. The NADPH-diaphorase assay showed a significant decrease of activity in the BAC-treated LOS, but no differences in the oesophageal body compared to controls. Several of these radiologic, manometric and histological observations resemble features of achalasia and the mechanism of the tonic pressure increase at this early time point appears to be due to a non-cholinergic mechanism.
Singaram
C
C
Division of Gastroenterology, Medical School, University of Wisconsin-Madison, USA.
Sweet
M A
MA
Gaumnitz
E A
EA
Bass
P
P
Snipes
R L
RL
D000818:Animals; D004195:Disease Models, Animal; D004931:Esophageal Achalasia / Q000503:physiopathology*; D005260:Female; D006651:Histocytochemistry; D008297:Male; D009252:NADPH Dehydrogenase / Q000378:metabolism; D009893:Opossums; D051381:Rats
D009252:NADPH Dehydrogenase