VV-hemorphin-7 and LVV-hemorphin-7 released during in vitro peptic hemoglobin hydrolysis are morphinomimetic peptides.

Two opioid peptides were generated by in vitro pepsin treatment of bovine hemoglobin. These peptides were identified using a GPI test and purified using HPLC chromatographic techniques. They correspond to fragments 31-40 (LVV-hemorphin-7) and 32-40 (VV-hemorphin-7) of the beta-chain of bovine hemoglobin. Binding experiments strongly confirm that VV-hemorphin-7 and LVV-hemorphin-7 are opioid peptides since they inhibited [3H]naloxone binding to rat brain membranes. Our results indicate that VV-hemorphin-7 and LVV-hemorphin-7 exhibit a lesser potency both in GPI and binding tests. Selectivity and affinity of these purified peptides and synthetic hemorphin-7 for opioid receptors is discussed.

Purification and characterization of enkephalin-related peptides released by in vitro peptic digestion of bovine plasma proteins.

In vitro pepsin treatment of plasma proteins generates biologically active peptides such as enkephalin-related peptides. These peptides were characterized using chromatographic techniques along with a radioimmunoassay procedure involving the use of Leu-enkephalin and Met-enkephalin antisera. Serum albumin is the only existing source of Met-enkephalin-immunoreactive peptides. One of these peptides consists of nine residues with the sequence NH2-Glu-Lys-Leu-Gly-Glu-Tyr-Gly-Phe-Gln; a second immunoreactive peptide might be the hexapeptide NH2-Gly-Glu-Tyr-Gly-Phe-Gln, which has been already identified in a rat serum albumin hydrolysate. Our results indicate that immunoglobulins constitute the main source of Leu-enkephalin-immunoreactive peptides. Immunoreactive NH2-Tyr-Phe-Leu was isolated from pepsin-treated bovine immunoglobulins. Binding experiments and cyclic nucleotide measurements suggested that this peptide was an enkephalin-related peptide. Similar experiments could be carried out to identify the proteins that contain enkephalin-like peptide sequences with the view to investigating the various biological processes occurring in enzymatically treated proteins.

Nutritional value and intestinal effects of dipeptides and tripeptides. Comparison with their issuing bovine plasma protein in rats.

A hydrolysate containing 75% di- and tripeptides (DTP) was prepared from bovine plasma proteins (BP) and the original protein and hydrolysate were compared for nutritional value. Food intake, protein efficiency ratio (PER), nitrogen balance and digestibility and plasma amino acid concentrations were measured in young rats receiving the diets over 17 days. Moreover, intestinal adaptation was evaluated in duodenum, jejunum and ileum, with the aid of light microscopy and enzyme analyses; tritiated thymidine incorporation was also measured. In DTP- and BP-fed rats, food intake, body weight gain, nitrogen balance and digestibility as well as PER were similar. Plasma amino acid concentration analyses showed an increased concentration of threonine and valine in the BP-fed group. Measurements of mucosal enzyme activities suggest adaptation to the diets especially in the ileum as indicated by increasing aminopeptidase N and dipeptidyl peptidase IV specific activities in the BP-fed group. This group also displayed substantial 3H-thymidine incorporation. It is concluded that the hydrolysate containing di- and tripeptides is efficiently utilized in healthy growing rats, though the efficacy is not higher than with the BP diet except for the difference in 3H-thymidine incorporation.

[Influence of age, season and hypophysectomy on lipogenesis of adipocyte from rabbit. Insulin effects]. / Influences de l'âge, de la saison et de l'hypophysectomie sur la lipogenèse de l'adipocyte chez le lapin; effects de l'insuline.

We studied lipogenesis, either from glucose or from acetate, spontaneous or stimulated by insulin, at the level of the isolated adipocyte of the rabbit's perirenal adipose tissue related to growth, season and hormonal troubles induced by hypophysectomy. 1. For the adipocyte, acetate instead of glucose is the major precursor for fatty acid synthesis. 2. Adipocyte lipogenesis of the immature rabbit of two months is higher than that which is observed in the mature rabbit of six months. 3. Adipocyte lipogenesis is strikingly more important in autumn than in spring, both in the young rabbit and the mature one. 4. After hypophysectomy, fatty acid synthesis from acetate is greatly increased at the level of the adipocyte and, in this case, insulin stimulates efficiently lipogenesis from acetate as well as from glucose.

[Season variations in lipolysis activity of adipocytes from fox, badger and hedgehog]. / Variations saisonnières de la lipolyse des adipocytes de Renard, de Blaireau et de Hérisson. Relation avec les cycles annuels des activités testiculaire et thyroïdienne.

1. We have studied the seasonal variations of the lipolytic response to a beta agonist, isoproterenol, and to theophylline of the isolated adipocyte from fox, badger and hedgehog, related to the circannual variations of testes and thyroid activities. 2. With the fox, we find a coincidence, in spring, between the maximum lipolytic sensitivity of the adipocyte, the thyroid function and the return to sexual rest. 3. With the badger, in winter, the maximum reaction of the adipocyte is contemporary with testes activity and with thyroid rest. 4. With the hedgehog, we observe two maximums in the sensitivity of the adipocyte to the lipolytic agents, one in spring, which coincides with the maximal testes and thyroid activities, the other in autumn, before the deep hibernation state. 5. In conclusion, there is, with these wild mammals, a seasonal variation in the lipolytic reaction of adipocyte which coincides with that of energy needs.

[The effects of adrenalectomy and of hydrocortisone administration on adenylate cyclase activity in rabbit adipose cells (author's transl)]. / Effets de la surrénalectomie et de l'administration d'hydrocortisone sur l'activité de l'adénylate cyclase de cellules adipeuses du lapin

Adenylate cyclase activity in rabbit adipocyte plasma membranes was studied with special reference to the effects of adrenalectomy and administration of cortisol in vivo. Adrenalectomy was accompanied by an increase in adenylate cyclase activity during basal conditions; cortisol (5 mg/kg body wt., intramuscularly) partly prevents this effect of adrenalectomy. The response of adenylate cyclase to corticotropin, epinephrine and norepinephrine stimulation was higher in the adrenalectomized rabbit than in the sham operated animal. Our in vitro results were in agreement with the striking fat mobilization observed in rabbit plasma after adrenalectomy and with the hypolipemic effects of cortisol we had previously observed in both normal and adrenalectomized rabbit.

[Fat and glucose mobilization in the hypophysectomized rabbit (author's transl)]. / Effets de l'hypophysectomie sur la circulation des lipides et des glucides chez le lapin

1. The metabolic behaviour of the fed hypophysectomized rabbit is quite different from that of the fed normal rabbit, i.e. in the hypophysectomized rabbit we found lasting hypoglycemia and a persistent high lipid plasma level. 2. Fasting induced a large and fast decrease in plasma glucose level which led to a coma; simultaneously it appeared that the hypophysectomized rabbit could not mobilize its adipose stores and that it quickly used up its plasma lipids, among them the essential fatty acids. In contrast, fasting in the normal rabbit induced a large fat mobilization from fat stores and the saturated fatty acids were essentially used, but at the same time plasma glucose remained near the level of control value. 3. Our in vitro results showed the important effect of synacthen in the lipolytic process of isolated fat cells.

[Hormonal control of the adenyl cyclase activity of adipose cell membranes prepared from badger, rabbit, fox and rat adipose tissues]. / Contrôle hormonal de l'activité adénylate cyclase de membranes de cellules adipeuses préparées à partir du tissus adipeux de blaireau, lapin, renard et rat

1. We have shown differences in hormonal regulation of adenylate cyclase activity in fat cell ghosts prepared from rat, rabbit, fox and badger adipose tissue, under the influence of catecholamines, ACTH and insulin. a) In the rat, catecholamines induced a large stimulation (+315%) of adenylate cyclase. b) In the rabbit, ACTH was the most effective hormone. c) In the fox and the badger, only catecholamines could stimulate adenylate cyclase. d) In both rat and rabbit, insulin did not reduce spontaneous enzymatic activity. Moreover, the activation of adenylate cyclase by ACTH in the rabbit was not altered by insulin, while in the rat, this hormone slightly decreased epinephrine stimulation. 2. Hormonal regulation of adenylate cyclase correlated with the lipolytic response.