The histamine concentration of duodenum and jejunum in rats is lower following vagotomy with gastrectomy or pyloroplasty than after gastrectomy or pyloroplasty alone. These changes may relate to known alterations in postvagotomy gastrointestinal motility. A lack of alteration in postvagotomy gastric histamine concentration has been confirmed and does not support a role of histamine in decreased gastric acid secretion following vagotomy. Whereas serotonin concentration of the proximal small intestine is decreased by loss of pyloric sphincter mechanism with or without vagotomy, histamine concentrations appear dependent on vagal integrity.
Reichle FA, Newcomer DL, Brigham MP, Reichle RM, Labinsky L, Rosemond GP. The Effect of Vagotomy on the Histamine Content of the Gastrointestinal Tract. Arch Surg. 1971;103(2):133–139. doi:10.1001/archsurg.1971.01350080049007