A hormonal role for endogenous opiate alkaloids: vascular tissues.
The distribution of morphine-containing cells in the central nervous system, adrenal gland, and its presence in blood may serve to demonstrate that this signal molecule can act as a hormone besides its role in cell-to-cell signaling within the brain. This speculative review is the result of a literature evaluation with an emphasis on studies from our laboratory. Opioid peptides and opiate alkaloids have been found to influence cardiac and vascular function. They have also been reported to promote ischemic preconditioning protection in the heart. Given the presence of morphine and the novel mu(3) opiate receptor on vascular endothelial cells, including cardiac and vascular endothelial cells in the median eminence, it would appear that endogenous opiate alkaloids are involved in modulating cardiac function, possible at the hormonal level. This peripheral target tissue, via nitric oxide coupling to mu opiate receptors, may serve to down regulate the excitability of this tissue given the heart's high performance state as compared to that of the saphenous vein, a passive resistance conduit. With this in mind, morphine and other endogenous opiate alkaloids may function as a hormone.
Stefano
George B
GB
Neuroscience Research Institute, State University of New York/College at Old Westbury, Old Westbury, New York 11568, USA. gstefano@sunynri.org
Zhu
Wei
W
Cadet
Patrick
P
Mantione
Kirk
K
Bilfinger
Thomas V
TV
Bianchi
Enrica
E
Guarna
Massimo
M
D000470:Alkaloids / Q000378:metabolism*; D000818:Animals; D001808:Blood Vessels / Q000502:physiology*; D004723:Endorphins / Q000502:physiology*; D006728:Hormones / Q000502:physiology*; D006801:Humans
D000470:Alkaloids; D004723:Endorphins; D006728:Hormones