RESUMO
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.
Assuntos
Hemoglobinas/metabolismo , Morfina/agonistas , Fragmentos de Peptídeos/metabolismo , Receptores Opioides/agonistas , Animais , Ligação Competitiva , Bovinos , Ala(2)-MePhe(4)-Gly(5)-Encefalina , Encefalina Leucina/análogos & derivados , Encefalina Leucina/farmacologia , Encefalinas/farmacologia , Cobaias , Hidrólise , Íleo/metabolismo , Masculino , Naloxona/farmacologia , Pepsina A/metabolismo , Ratos , Ratos Wistar , Sensibilidade e EspecificidadeRESUMO
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.
Assuntos
Proteínas Sanguíneas/isolamento & purificação , Encefalinas/isolamento & purificação , Oligopeptídeos/isolamento & purificação , Sequência de Aminoácidos , Animais , Proteínas Sanguíneas/genética , Proteínas Sanguíneas/farmacologia , Encéfalo/metabolismo , Bovinos , AMP Cíclico/metabolismo , Encefalinas/genética , Encefalinas/farmacologia , Cobaias , Íleo/efeitos dos fármacos , Técnicas In Vitro , Masculino , Dados de Sequência Molecular , Oligopeptídeos/genética , Oligopeptídeos/farmacologia , Pepsina A , Ensaio Radioligante , Ratos , Ratos Wistar , Receptores Opioides/metabolismoRESUMO
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.
Assuntos
Aminopeptidases , Proteínas Alimentares/farmacologia , Dipeptídeos/farmacologia , Intestino Delgado/efeitos dos fármacos , Peptídeo Hidrolases/farmacologia , Animais , Proteínas Alimentares/administração & dosagem , Dipeptídeos/administração & dosagem , Alimentos Formulados , Masculino , Valor Nutritivo , Peptídeo Hidrolases/administração & dosagem , Ratos , Ratos EndogâmicosRESUMO
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.
Assuntos
Tecido Adiposo/metabolismo , Carnívoros/fisiologia , Raposas/fisiologia , Ouriços/fisiologia , Lipólise , Estações do Ano , Testículo/fisiologia , Glândula Tireoide/fisiologia , Tecido Adiposo/citologia , Tecido Adiposo/efeitos dos fármacos , Animais , Relógios Biológicos , Isoproterenol/farmacologia , Masculino , Teofilina/farmacologiaRESUMO
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.
Assuntos
Tecido Adiposo/metabolismo , Insulina/farmacologia , Metabolismo dos Lipídeos , Acetatos/metabolismo , Tecido Adiposo/citologia , Tecido Adiposo/efeitos dos fármacos , Envelhecimento , Animais , Glucose/metabolismo , Hipofisectomia , Coelhos , Estações do Ano , Fatores de TempoRESUMO
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.
Assuntos
Metabolismo dos Carboidratos , Mobilização Lipídica , Hipófise/fisiologia , Tecido Adiposo/metabolismo , Animais , Glicemia/metabolismo , Cosintropina/farmacologia , Coma Diabético/etiologia , Hipofisectomia , Mobilização Lipídica/efeitos dos fármacos , Lipídeos/sangue , Coelhos , InaniçãoRESUMO
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.
Assuntos
Adenilil Ciclases/metabolismo , Tecido Adiposo/enzimologia , Hidrocortisona/farmacologia , Glândulas Suprarrenais/fisiologia , Adrenalectomia , Hormônio Adrenocorticotrópico/farmacologia , Animais , Membrana Celular/enzimologia , Epinefrina/farmacologia , Masculino , Norepinefrina/farmacologia , CoelhosRESUMO
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.