Further Concerning a Parasympathetic Center in the Interbrain

Abstract

The presence of impurities, possibly histamine, in commercial pituitrin had been suggested as a probable cause of the flushing responses to pituitrin when injected intraven tricularly in man. Intraventricular histamine, however, gave no flushing effects at all comparable to those produced by an intramuscular injection. Intraventricular injections of pituitrin and pilocarpine caused a marked parasympathetic (vagal) stimulatory effect on gastric motility whereas the intramuscular injections of pituitrin promptly inhibited gastric motility. These observations were interpreted as a further support to the view thatintraventricular pituitrin and pilocarpine stimulated a central (probably tuberal) parasympathetic centre.