ACTH-(1-24) enhances the electrically stimulated release of [3H]dopamine from rat septal slices via a dopamine D2 receptor-independent mechanism.
ACTH-(1-24) enhanced the basal as well as the electrically stimulated release of [3H]dopamine from rat septal slices in vitro. In the absence of Ca2+ from the superfusion medium the effect of ACTH-(1-24) on the electrically stimulated release of [3H]dopamine was abolished. The stimulus-evoked release of [3H]dopamine from septal slices appeared to be modulated through dopamine receptors of the D2 subtype: the dopamine D2 receptor agonists 2-(N-propyl-N-2-thienylethylamino)-5-hydroxytetralin (N-0437) and quinpirole reduced, whereas the dopamine D2 receptor antagonist sulpiride enhanced the electrically stimulated release of [3H]dopamine. The magnitude of the effect of ACTH-(1-24) on [3H]dopamine release was the same in the presence or absence of N-0437, quinpirole and sulpiride. ACTH-(1-24) had no effect on either the basal or the electrically stimulated release of [3H]noradrenaline. Also when the electrically stimulated release of [3H]noradrenaline was reduced by the alpha 2-adrenoceptor agonist clonidine, the peptide was without effect. These results show that ACTH-(1-24) selectively enhances the release of [3H]dopamine from septal slices. The effect of the peptide is independent of the degree of activation of dopamine D2 receptors which modulate the stimulus-evoked release of [3H]dopamine. These results suggest that ACTH-(1-24) enhances the stimulus-evoked release of dopamine in the septum via a mechanism not associated with dopamine D2 autoreceptors.
Florijn
W J
WJ
Rudolf Magnus Institute, University of Utrecht, Medical Faculty, The Netherlands.
Versteeg
D H
DH
D000324:Adrenocorticotropic Hormone; D000818:Animals; D003366:Cosyntropin / Q000494:pharmacology*; D004298:Dopamine / Q000378:metabolism*; D018492:Dopamine Antagonists; D004558:Electric Stimulation; D004873:Ergolines / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D019257:Quinpirole; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects / Q000378:metabolism*; D017448:Receptors, Dopamine D2; D012686:Septal Nuclei / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D012688:Septum Pellucidum / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D013469:Sulpiride / Q000494:pharmacology
D018492:Dopamine Antagonists; D004873:Ergolines; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D003366:Cosyntropin; D019257:Quinpirole; D013469:Sulpiride; D000324:Adrenocorticotropic Hormone; D004298:Dopamine; D009638:Norepinephrine