title: Comparative effects of the ACTH 4-9 analogue (ORG 2766), ACTH 4-10 and [D-Phe7] ACTH 4-10 on medial septal self-stimulation behaviour in rats.
abstract: Experiments were performed to examine the effects of various analogues of ACTH on electrical self-stimulation behaviour elicited from the medial septal area using an ascending or descending sequence of stimulus intensities within a session. When an ascending sequence of threshold multiples was used ACTH 4-10 and the ACTH 4-9 analogue (ORG 2766) enhanced level pressing for low intensity stimulation but attenuated self-stimulation at greater current intensities. The analogue ORG 2766 appeared to be a thousand times more potent than ACTH 4-10; [D-Phe7] ACTH 4-10 inhibited the response rate at threshold level but was inactive at greater current intensities. The same effect was found following administration of ORG 2766 in a dose which was 20 times greater (1 microgram/rat) than that used in the first experiments. Lever pressing was not affected by treatment with ACTH 4-10 or ORG 2766 when a descending sequence of stimulus intensities was used within a session. Thus, ACTH-related peptides may affect motivational processes involved in self-stimulation rather than the reward of the stimulation per se. It is suggested that although ORG 2766 mimicked the action of ACTH 4-10 this synthetic peptide may have additional behavioural properties.
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D004558:Electric Stimulation; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012653:Self Stimulation / Q000187:drug effects*; D012688:Septum Pellucidum / Q000187:drug effects / Q000502:physiology*; D013329:Structure-Activity Relationship
chemical_list: D010446:Peptide Fragments; C034159:ACTH (4-10), Phe(7)-; C013765:Org 2766; D000324:Adrenocorticotropic Hormone; C011394:ACTH (4-10)