Release of enkephalins and enkephalin-containing polypeptides from perfused beef adrenal glands.

Abstract

Enkephalins and enkephalin-containing polypeptides were released from perfused bovine adrenal glands bynicotine and Ba2+, agents that release catecholamines. All the enkephalin-containing polypeptides that are normally found in the a renal medulla were released by the two secretagogues in approximately the same proportions as are present in adrenal chromaffin granules.It has long been thought that the function of the adrenal medulla is to secrete catecholamines, mainly epinephrine, in response to stressful stimuli. However, it was recently reported that, in addition to catecholamines, adrenal chromaffin vesicles are also rich in another class of physiologically active substances, the enkephalins (1-3). We verified this and found that the adrenal medulla contains not only [Met]-and [Leujenkephalin but also several larger polypeptides, each containing one or more enkephalin sequences within its primary structure (4-9). Treatment of the enkephalin-containing polypeptides with trypsin and carboxypeptidase B generates free [Met]-and [Leu]enkephalins. We have identified six major classes of enkephalin-containing proteins corresponding to molecular weights of ;50,000, 22,000, 14,000, 8000, 2000-5000, and t1000 (enkephalin plus enkephalin-containing hexa-and heptapeptides) (4,5,8). These polypeptides appear to be precursors and intermediates in a biosynthetic pathway leading to enkephalin; such a relationship is supported by pulse-chase experiments (10).The presence of these polypeptides within chromaffin vesicles raises the possibility that one or more of the larger metabolic intermediates serve as an adrenal hormone. To perform such a role, a substance must be secreted from the adrenal medulla during splanchnic nerve stimulation. The present studies demonstrate that each of the enkephalin-containing peptides and proteins stored in chromaffin vesicles is secreted from perfused bovine glands after stimulation with nicotine or Ba2+. METHODSFresh bovine adrenal glands were cannulated through the adrenal vein and perfused in a retrograde fashion with Mg2+-free Locke's solution at arate of 4 ml/min. Glands were perfused in this manner for at least 30 min prior to the addition of secretagogues. Perfusates were collected in 40-ml fractions into plastic tubes containing 4 ml of 10 M acetic acid/200 mM HCI/1.0% 2-mercaptoethanol with 10 Ag each of pepstatin A and phenylmethanesulfonyl fluoride per ml and were placed on ice immediately after collection. Chromaffin vesicles were isolated from adrenal medulla and extracted as described (4).The 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. 7473Catecholamines were determined by the trihydroxyindole method (11)

Antihyperglycaemic action of diosmin, a citrus flavonoid, is induced through endogenous β‐endorphin in type I‐like diabetic rats

“…Thus, we focused on the source of endogenous opioids. The adrenal gland is known to synthesize and release opioid peptides including β‐endorphin . Therefore, we employed bilateral adrenalectomy to verify the source of the increased plasma BER observed in STZ‐diabetic rats induced by diosmin.…”

Changes in plasma proenkephalin peptide F and catecholamine levels during graded exercise in men.

“…The enkephalin-containing polypeptides (ECPs) found in the adrenal medullary chromaffin cells have been shown to be secreted in response to the same stimuli that induce epinephrine release (8)(9)(10). Since exercise stimulates catecholamine release, specifically epinephrine (11)(12)(13), it was hypothesized that the ECPs would also respond to exercise stress.…”

Co‐release of enkephalins and precursors with catecholamines from the perfused cat adrenal gland in situ.

“…Previous studies and the present work have shown that sequential enzymatic digestion of the peptides of the adrenal gland generates up to 80-90 % ofthe total (met)enkephalin immunoreactivity. It has already been found (Kilpatrick et al 1980;Rossier et al 1981) that the large enkephalincontaining peptides are released together with catecholamines in response to physiological stimuli. The results given in the present paper indicate that such an assumption may be erroneous since we have found that, in response to electrical stimulation of the splanchnic nerves, one-half of the total (met)enkephalin immunoreactivity released comprises free (met)enkephalin, (met)enkephalyl-arg-phe and (met)enkephalyl-arg-gly-leu.…”

“…Several studies have indicated that enkephalin immunoreactive products or opioid peptide-like products are co-released with catecholamines from the adrenal medulla in vitro (Kilpatrick, Lewis, Stein & Udenfriend, 1980;Stine, Yang & Costa, 1980;Livett, Dean, Whelan, Udenfriend & Rossier, 1981; Udenfriend, 1981; Corder, Mason, Perrett, Lowry, Clement-Jones, Linton, Besser & Rees, 1982) and in vivo (Hexum, Hanbauer, Govoni, Yang & Costa, 1980; Govoni, Hanbauer, Hexum, Yang, Kelly & Costa, 1981). Furthermore, it was recently shown (Livett, Day, Elde & Howe, 1982;Pelto-Huikko, Salminen & Hernoven, 1982) that in the adrenal medulla, enkephalin immunoreactivity is present in adrenergic chromaffin cells but not in noradrenergic cells.…”