Respective role of mu and delta opioid receptors in the antidepressant-like effects induced by endogenous opioid peptides enkephalins

In rats and rabbits, endogenous opioid peptides participate in ischemic preconditioning. However, it is not known which endogenous opioid(s) can trigger cardioprotection. We examined preconditioning-induced and opioid-induced limitation of cell death in isolated, calcium-tolerant, adult rabbit cardiomyocytes. Cells were subjected to simulated ischemia by pelleting and normothermic hypoxic incubation. Preconditioning was elicited with 15 min of simulated ischemia followed by 15 min of resuspension and reoxygenation. All cells underwent 180 min of simulated ischemia. Cell death was assessed by trypan blue permeability. Morphine protected cells, as did preconditioning; naloxone blocked the preconditioning-induced protection. Exogenous Met5-enkephalin (ME) induced protection, but exogenous β-endorphin did not. ME-induced protection was blocked by the δ-selective antagonist naltrindole. Additionally, two other proenkephalin products, Leu5-enkephalin and Met5-enkephalin-Arg-Phe, provided protection equipotent to ME. These data suggest that one or more proenkephalin products interact with δ-opioid receptors to endogenously trigger opioid-mediated protection.

Download Full-text

Opioid Receptors and Endogenous Opioid Peptides

Opioid Dependence ◽

10.1007/978-1-4684-3866-6_4 ◽

1980 ◽

pp. 69-94

Author(s):

Abraham Wikler

Keyword(s):

Opioid Receptors ◽

Opioid Peptides ◽

Endogenous Opioid Peptides ◽

Endogenous Opioid

Download Full-text

The Hypothalamic Control of the Menstrual Cycle and the Role of Endogenous Opioid Peptides

Proceedings of the 1983 Laurentian Hormone Conference ◽

10.1016/b978-0-12-571140-1.50015-3 ◽

1984 ◽

pp. 441-485 ◽

Cited By ~ 2

Author(s):

MICHEL FERIN ◽

DEAN VAN VUGT ◽

SHARON WARDLAW

Keyword(s):

Menstrual Cycle ◽

Opioid Peptides ◽

Endogenous Opioid Peptides ◽

Endogenous Opioid ◽

Hypothalamic Control

Download Full-text

The role of opiates and endogenous opioid peptides in the regulation of rat TSH secretion

Brain Research ◽

10.1016/0006-8993(81)90296-1 ◽

1981 ◽

Vol 219 (2) ◽

pp. 335-344 ◽

Cited By ~ 33

Author(s):

Burt Sharp ◽

John E. Morley ◽

Harold E. Carlson ◽

Jody Gordon ◽

Jacqueline Briggs ◽

...

Keyword(s):

Opioid Peptides ◽

Endogenous Opioid Peptides ◽

Endogenous Opioid ◽

Tsh Secretion

Download Full-text

Endogenous opioids and ventilatory responses to hypercapnia in normal humans

Journal of Applied Physiology ◽

10.1152/jappl.1985.58.5.1415 ◽

1985 ◽

Vol 58 (5) ◽

pp. 1415-1420 ◽

Cited By ~ 8

Author(s):

S. E. Weinberger ◽

R. A. Steinbrook ◽

D. B. Carr ◽

E. R. von Gal ◽

J. E. Fisher ◽

...

Keyword(s):

Opioid Peptides ◽

Endogenous Opioids ◽

Opiate Antagonist ◽

Endogenous Opioid Peptides ◽

Short Term ◽

Endogenous Opioid ◽

Beta Endorphin ◽

Ventilatory Responses ◽

Normal Humans

Though administration of opioid peptides depresses ventilation and ventilatory responsiveness, the role of endogenous opioid peptides in modulating ventilatory responsiveness is not clear. We studied the interaction of endogenous opioids and ventilatory responses in 12 adult male volunteers by relating hypercapnic responsiveness to plasma levels of immunoactive beta-endorphin and by administering the opiate antagonist naloxone. Ventilatory responsiveness to hypercapnia was not altered by pretreatment with naloxone, and this by itself suggests that endogenous opioids have no role in modulating this response. However, there was an inverse relationship between basal levels of immunoactive beta-endorphin in plasma and ventilatory responsiveness to CO2. Furthermore, plasma beta-endorphin levels rose after short-term hypercapnia but only when subjects had been pretreated with naloxone. We conclude that measurement of plasma endorphin levels suggests relationships between endogenous opioid peptides and ventilatory responses to CO2 that are not apparent in studies limited to assessing the effect of naloxone.

Download Full-text