The Central Nervous System in Relation to the Digestive Functions

Abstract

In this communication a comparison is made between certain secretory, motor and vascular phenomena produced by pilocarpine administered into the cerebral ventricles of monkeys, and the corresponding responses to the drug when given subcutaneously. A series of 15 green monkeys (Lasiopyga callithricus) has been used. On 6 of them, fractional gastric analyses have been made following the administration by stomach tube of 100 cc. of a farina test-meal. Several experiments have been conducted on each animal to demonstrate the action of the drug pilocarpine (hydrochloride), when administered at various times in the course of digestion of the test-meal. The drug has been given in varying doses subcutaneously and by the intraventricular route. The intraventricular injection of pilocarpine, in doses of 5-10 mg. per kilo of body weight, invariably caused a sudden and complete cessation of the gastric secretion of free HCl, at whatever stage in the digestion the drug was given. The samples obtained after pilocarpine injection consistently failed to show any free HCl acid. The total acidity curve usually paralleled the'free acid'curve but at a higher level. After intraventricular injection of pilocarpine, the total acid generally fell pari passu with the'free'acid. This fact, together with the lessened volume of recoverable gastric contents, indicates that the phenomenon is not merely one of neutralization by mucus or regurgitated bile. In one monkey with a low type of acid curve the level of total acidity merely ceased to rise. The'free'acid in this case fell to zero. If a subcutaneous injection of histamine (1-2 mg. per kilo) was given in the achlorhydric phase following intraventricular pilocarpine administration, the “acid tide”—both ‘free’ and ‘combined’—was rapidly restored and reached a high level.