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  • Author or Editor: Alton R. Esdaile x
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Objective—To investigate the effect of adrenalectomy on cholecystokinin-8 (CCK-8)–induced Fos-like immunoreactivity (Fos-LI) in the myenteric neurons of the dorsal vagal complex (DVC) in rats.

Animals—16 male Sprague Dawley rats.

Procedures—Rats were allocated to 1 of 2 groups and underwent adrenalectomy or a sham adrenalectomy procedure. Rats were challenged with a supraphysiologic dose of CCK-8 (40 μg/kg) or physiologic saline (0.9% NaCl) solution (0.5 mL) administered IP; after 90 minutes, rats were euthanized, and Fos-LI was quantified in the DVC (at the levels of the area postrema, nucleus tractus solitarii, and dorsal motor nucleus of the vagus) and the myenteric neurons of the duodenum and jejunum by use of a diaminobenzidine reaction enhanced with nickel. The Fos-LI–positive cells were counted by use of an automated system and manually in the DVC and intestinal samples, respectively. Counts of Fos-LI in the different hindbrain levels and myenteric neurons were compared between the adrenalectomy- and shamtreated groups and between the CCK-8– and saline solution–treated groups.

Results—After adrenalectomy, CCK-8–induced Fos-LI was attenuated only in the myenteric neurons of the duodenum.

Conclusions and Clinical Relevance—Results indicate that the adrenal gland has a role in the activation of myenteric neurons by CCK-8 in rats.

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in American Journal of Veterinary Research


Objective—To evaluate the role of cholecystokinin (CCK)-receptor antagonists in the activation of enteric and hindbrain neurons by sulfated CCK-8.

Animals—81 male Sprague-Dawley rats.

Procedure—Rats were allocated to 10 groups (5 to 22 rats/group). Each rat received 2 IP injections (15 minutes between injections). The first injection consisted of a specific CCK2-receptor (CCK2R) antagonist (L365,260; 150, 500, or 1,000 µg/kg), a specific CCK1-receptor (CCK1R) antagonist (devazepide; 150 µg/kg), or 1% dimethyl sulfoxide (DMSO [ie, vehicle]), and the second injection consisted of sulfated CCK-8 (10 µg/kg) or saline (0.9% NaCl) solution. Rats were anesthetized and perfused with 500 mL of Krebs saline solution, and the myenteric plexuses of the duodenum and jejunum were collected. Rats were then perfused with 500 mL of phosphate-buffered 4% formaldehyde solution; rats were then euthanatized, and the hindbrain of each was harvested. Tissues were stained by use of a diaminobenzidine reaction enhanced with nickel to reveal Fos-like immunoreactivity (Fos-LI), a marker of neuronal activation, in the aforementioned neurons.

Results—Sulfated CCK-8 significantly increased Fos- LI in the myenteric and hindbrain neurons, compared with values for the DMSO injections. All dosages of L365,260 failed to attenuate this increase; however, injection of devazepide attenuated the increase in Fos-LI.

Conclusions and Clinical Relevance—Analysis of the results of this study reveals that sulfated CCK-8 activates myenteric and hindbrain neurons of rats primarily through CCK1R. It provides evidence that CCK2R are lacking or not functional in the gastrointestinal tract of rats. (Am J Vet Res 2005;66:1308–1313)

Full access
in American Journal of Veterinary Research