The involvement of dopamine and nitric oxide in the endocrine and behavioural action of endomorphin-1
by
Bujdoso E, Jaszberenyi M, Gardi J, Foldesi I, Telegdy G.
University of Szeged,
Department of Pathophysiology,
Albert Szent-Gyorgyi Medical and Pharmaceutical Centre,
Neurohumoral Research Group of Hungarian Academy of Sciences,
PO Box 427, 6701 Szeged, Hungary.
Neuroscience. 2003;120(1):261-8.

ABSTRACT

Previous publications have demonstrated a prominent central and corticotropin releasing hormone-mediated action of the endomorphins (EMs) on both open-field behaviour and the hypothalamo-pituitary-adrenal (HPA) axis. In the present experiments, the direct action of endomorphin-1 (EM1) on pituitary adrenocorticotropic hormone (ACTH) release, adrenal corticosterone secretion and the roles of nitric oxide (NO) and dopamine (DA) in the HPA and behavioural responses elicited by EM1 were investigated in mice. In vitro perifusion studies indicated that the action of EM1 on the HPA system appears to be confined to the hypothalamus, as EM1 did not influence the corticosterone secretion from adrenal slices and moderately attenuated the ACTH release from anterior pituitary slices. In in vivo experiments, NG-nitro-L-arginine (L-NNArg) pretreatment brought about a profound inhibition of both the endocrine and the behavioural responses. On the other hand, haloperidol completely abolished the increases in square crossing and rearing, without affecting corticosterone release. The direct action of EM1 on striatal DA release was therefore also investigated in an in vitro superfusion system. Although EM1 did not influence the basal release of tritiated DA, it significantly enhanced the transmitter release evoked by electric impulses and pretreatment with L-NNArg resulted in a considerable inhibition of the release elicited by EM1. In conclusion, our endocrine studies suggest an important role of NO in the mediation of the EM1-evoked corticosterone secretion. They also indicate that EM1 activates the HPA axis at a hypothalamic level and dopamine is not involved in this process. In contrast, the behavioural experiments reflect that the locomotor activation induced by EM1 is mediated by NO and dopamine, and the superfusion studies demonstrate that NO transmits the dopamine release enhancing effect of EM1.

Pain
LAAM
Tolerance
Sugar junkies
Knockout mice
Opium timeline
Opioid receptors
Endomorphins 1 and 2
The Pleasures of Opium
Endomorphins and the mouse
Endomorphins and rodent brains
Adenylyl cyclase superactivation
The degradation of endomorphins
Endomorphins and the mu-opioid receptor
Endomorphins and related opioid peptides
Morphine: a mood-brightening smart-drug?
Opioids, depression and learned helplessness
Endomorphin-1, accumbal dopamine and the mu-opioid receptor
A peripherally administered endomorphin-1 analogue offers pain relief

Refs
and further reading

HOME
HedWeb
Nootropics
cocaine.wiki
Future Opioids
BLTC Research
MDMA/Ecstasy
Superhapiness?
Utopian Surgery?
The Abolitionist Project
The Hedonistic Imperative
The Reproductive Revolution
Critique of Huxley's Brave New World

The Good Drug Guide
The Responsible Parent's Guide
To Healthy Mood Boosters For All The Family