Corticotropin regulates trans-synaptically the activity of septo-hippocampal cholinergic neurones

Abstract

The activity of septo-hippocampal neurons is affected by the action on cholinergic perikarya in the septum of a variety of putative neurotransmitters, including substance P and .beta.-endorphin. (The latter is released in the septal region from neurons which originate in the medial basal hypothalamus). Two other neuropeptides, ACTH1-24 and .alpha.-melanotropin (.alpha.-MSH), affect acetylcholine turnover in septo-hippocampal neurons in a manner that is not blocked by transection of the afferents to the hippocampus, from which it has been inferred that the neurotransmitters act directly on the hippocampus. Experiments with ACTH are described which show that the effect is the influence on septo-hippocampal cholinergic neurons of peptidergic neurons within the septum.