Properties and localization of beta-endorphin receptor in rat brain.

Abstract

Thus, by using such a washing procedure with the rapid filtration method, we were able to demonstrate a proteindependent and temperature-dependent high-affinity association of the 13h-[3H]endorphin with the brain membrane (7). Moreover, this high-affinity binding can be demonstrated to be stereospecific (7). The stereoactive isomer levorphanol or (-)naloxone was at least 1000-fold more potent in displacing 3h-[3H]endorphin binding than was the inactive isomer dextrorphan or (+)naloxone, respectively. When the binding of this radioactive ligand was determined at various concentrations and the binding data were analyzed by the method of Scatchard (10), a two-component or single site with negative cooperativity typical of the opiate binding was observed (Fig. 1). The Kd values (with 95% confidence limits) determined from linear regression analysis of the two binding Abbreviation: LPH, lipotropin. 5455The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact.

Hypothalamic regulation of the cardiovascular and respiratory systems: role of specific opiate receptors

“…The following studies were aimed at addressing this issue by microinjecting selective opiate receptor ligands into a discrete hypothalamic region (nucleus preopticus medialis; POM) known to play an important role in cardiovascular control (Brody, Haywood & Tuow, 1980), and in which the presence of opioid peptides and receptors have already been established (Goodman etal., 1980;Law, Loh & Li, 1979 (YSI,model 73A). The arterial line was attached to a Narco microtransducer (RP 1500i) for blood pressure and heart rate recording; respiratory rate and relative pneumatic impedance (RPI) were recorded by subcutaneous electrodes through a Narco RPI coupler (type 7212).…”

Plasma Norepinephrine, Epinephrine and Dopamine Responses to Intracerebral Administration of a Met-Enkephalin Analog, D-Ala²-Met-Enkephalinamide, in Rats

“…Also, their receptors in the brain may be different [2,5,8,9,26]. Thus, although some similarities are seen in pharmacologi cal responses to [3-endorphin and met-enkephalin, differen ces in responses should also be anticipated.…”

Sympathoadrenal control by paraventricular hypothalamic beta-endorphin in hypertension.

“…47 However, if the effects of 0-endorphin are mediated through an action on a specific /3-endorphin receptor (presumably the socalled ereceptor), the possibility still seems likely, since /3-endorphin is about 63 times more potent than naloxone in displacing [ 3 H]/3-endorphin in rat brain membrane preparations. 45 Naltrexone is only several times more potent for fi-and 5-opioid receptor blockades than naloxone, 46 although relative potencies for a specific /3-endorphin receptor between these two antagonists are not known. In addition, naltrexone is more lipophilic than 0-endorphin, suggesting its more rapid removal into the cell than /3-endorphin.…”

“…19 Moreover, /3-endorphin has binding characteristics distinct from those of other opioid agonists, in that divalent cations inhibit /3-endorphin binding in brain, suggesting a difference between /3-endorphin and alkaloid/enkephalin binding sites. 45 Thus, it is likely that there are naltrexoneresistant /3-endorphin receptors in the PVH. Another possible explanation is that naltrexone, due to its clearance from the PVH, no longer maintains a concentration to block £-endorphin-induced stimulatory responses 20 minutes after /3-endorphin injection.…”