Effects of ACTH and related peptides on medial septal self-stimulation

The effects of ACTH1-24, ACTH4-10, the ACTH4-9 analog Org 2766 and [D-Phe7] ACTH4-10 on medial septal self-stimulation were determined in the rat following intracerebroventricular (ICV) injections. Self-stimulation rates were increased by 0.01-10 micrograms ACTH1-24 or 0.1-10 micrograms ACTH4-10, but not by Org 2766 or [D-Phe7] ACTH4-10. A dose of 1 microgram ACTH1-24 ICV did not affect open field behaviour. Subcutaneous administration of 1 microgram ACTH1-24 did not influence self-stimulation in the septum. Thus, the ACTH1-24 effect appears to be a central effect and provides evidence for an influence of ACTH containing pathways on structures involved in maintaining self-stimulation behavior. A possible role of opiate receptors and dopaminergic neurons in this effect of ACTH1-24 is also discussed.