ABSTRACT
OBJECTIVES: Obesity is a metabolic and hormonal disorder with serious social and psychological impacts. There is a close relationship among obesity, neuroendocrine homeostasis and behavioral patterns. However, few data are available in the literature regarding this subject. This study assessed behavior and memory of adult obese rats by monosodium l-glutamate (MSG) neonatal treatment or highly palatable dietary treatment. METHODS: MSG obesity was induced by subcutaneous injections of MSG (4 mg/g) during the first 5 days of life (Ob-MSG); control group (C-MSG), received saline solution equimolar. Both groups were fed with commercial chow. To induce dietary obesity, 21-day-old rats were assigned to two experimental diets: highly palatable diet (Ob-Diet) and control diet (C-Diet) composed of commercial chow. Ninety-day-old animals were submitted to behavioral assessment by the open-field test and short- and long-term memory by the object recognition test. Biometric variables were obtained, the Lee index was calculated and mass of retroperitoneal and perigonadal fat pads was measured. Furthermore, an altered behavioral profile was investigated by quantification of plasmatic corticosterone, expression, and activity of hypothalamic extracellular signal-regulated kinase protein (ERK) 1 and 2. RESULTS: Increased Lee index and fat pads were observed in Ob-MSG and Ob-Diet groups. Ob-MSG presented a higher level of anxiety and impaired long-term memory compared to C-MSG, while there was no difference between Ob-Diet and C-Diet. The Ob-MSG group presented a higher level of plasmatic corticosterone and increased phosphorylation of hypothalamic ERK1 and 2. DISCUSSION: Both treatments induced obesity but only Ob-MSG showed altered behavioral parameters, which is related to increased concentration of corticosterone and hypothalamic ERK1 and 2 activation.
Subject(s)
Corticosterone/blood , Disease Models, Animal , Hypothalamus/metabolism , MAP Kinase Signaling System , Memory Consolidation , Neurons/metabolism , Obesity/metabolism , Animals , Animals, Newborn , Behavior, Animal/drug effects , Corticosterone/agonists , Enzyme Activation/drug effects , Hypothalamus/drug effects , Hypothalamus/enzymology , MAP Kinase Signaling System/drug effects , Male , Memory Consolidation/drug effects , Memory, Long-Term/drug effects , Memory, Short-Term/drug effects , Mitogen-Activated Protein Kinase 1/chemistry , Mitogen-Activated Protein Kinase 1/metabolism , Mitogen-Activated Protein Kinase 3/chemistry , Mitogen-Activated Protein Kinase 3/metabolism , Nerve Tissue Proteins/agonists , Nerve Tissue Proteins/metabolism , Neurons/drug effects , Neurons/enzymology , Obesity/blood , Obesity/chemically induced , Phosphorylation/drug effects , Protein Processing, Post-Translational/drug effects , Random Allocation , Rats, Wistar , Sodium Glutamate/toxicityABSTRACT
Synthetic supplements of conjugated linoleic acid (CLA) containing 50:50 mixture of cis-9, trans-11 and trans-10, cis-12 CLA isomers have been commercialized in some places for reducing body fat. However the safety of this CLA mixture is controversial and in some countries the CLA usage as food supplement is not authorized. Changes in insulinemic control and serum lipids profile are potential negative effects related to consumption of CLA mixture. The present study aimed to evaluate the effects of a diet containing mixture of cis-9, trans-11 and trans-10, cis-12 CLA on prevention of obesity risk as well as on potential side effects such as insulin resistance and dyslipidemia in Wistar rats. Thirty male Wistar rats were randomly assigned to the following dietary treatments (n=10/group), for 60 days: Normolipidic Control (NC), diet containing 4.0% soybean oil (SO); High Fat-Control (HF-C), diet containing 24.0% SO; High Fat-synthetic CLA (HF-CLA), diet containing 1.5% of an isomeric CLA mixture (Luta-CLA 60) and 22.5% SO. Luta-CLA 60 (BASF) contained nearly 60% of CLA (cis-9, trans-11 and trans-10, cis-12 CLA at 50:50 ratio). The HF-CLA diet contained 0.3% of each CLA isomer. HF-CLA diet had no effect on dietary intake and body composition. HF-CLA-fed rats had lower levels of PPARγ protein in retroperitoneal adipose tissue, hyperinsulinemia compared to HF-C-fed rats, hyperglycemia compared to NC-fed rats while no differences in glycemia were observed between NC and HF-C groups, increased HOMA index and higher levels of serum HDL cholesterol. Thus, feeding rats with a high fat diet containing equal parts of cis-9, trans-11 and trans-10, cis-12 CLA isomers had no effect on body composition and induced insulin resistance. Despite HF-CLA-fed rats had increased serum HDL cholesterol levels, caution should be taken before synthetic supplements containing cis-9, trans-11 and trans-10, cis-12 CLA are recommended as a nutritional strategy for weight management.
Subject(s)
Body Composition/drug effects , Cholesterol, HDL/blood , Dietary Supplements , Insulin Resistance , Linoleic Acids, Conjugated/adverse effects , Linoleic Acids, Conjugated/pharmacology , Animals , Dyslipidemias , Hyperglycemia , Hyperinsulinism , Intra-Abdominal Fat/metabolism , Isomerism , Linoleic Acids, Conjugated/chemistry , Male , Obesity/prevention & control , PPAR gamma/metabolism , Rats, WistarABSTRACT
Estudou-se o envolvimento dos pools intracelulares de Ca2+ na secreção de catecolaminas e o efeito da glicose e densidade celular sobre células cromafins. Em células cromafins de boi, a cafeína (50mM) inibiu totalmente a secreção de catecolaminas e os fluxos de 45Ca2+ induzidos por cabacol e nicotina e em 55,88 e 12,74 por cento, respectivamente, os estimulados por K+ elevado, como na secreção em células cromafins de rato. A pré-incubação com cafeína inibiu de forma tempodependente a secreção induzida por K+ (90,80 por cento aos seis minutos). Neste protocolo a captação de 45Ca2+ foi reduzida em 40,00 por cento no primeiro minuto. Concluímos que a cafeína tem efeito inibitório sobre a estimulação nicotínica e que o desequilíbrio da homeostase dos pools intracelulares de Ca2+ diminui a secreção de catecolaminas. O efeito da retirada de Na+ extracelular foi analisado. A secreção foi inversamente proporcional à concentração de Na+, na presença e ausência de Ca2+ extracelular. Reduzindo a incubação de 15 para 1 minuto, a secreção foi três vezes maior nos experimentos com Ca2+. Pré-incubação com cafeína reduziu a secreção estimulada pela retirada de Na+ e, em maior proporção, no meio com Ca2+. Concluímos que a diminuição da concentração de Na+ extracelular mobiliza Ca2+ de pools intracelulares e induz o influxo de Ca2+. Em células cromafins de feocromocitoma de rato, a glicose em altas concentrações (25,00 mM) diminuiu a expressão de tirosina hidroxilase (TH) e dopamina ß-hidroxilase (DBH). O aumento da desnsidade celular reduziu os níveis de DBH e feniletanolamina metiltransferase (PNMT) independentemente da concentração de glicose. A proliferação celular foi maior nas células cultivadas em meio com 5,5 mM de glicose, e significativamente diferente após 72h de cultivo. A glicose modificou o padrão de fosforilação de proteínas. Uma proteína de massa molecular aparente de 43 kDa apareceu fosforilada em resíduos de (FALTA ALGO)com 5,5 mM de glicose. O mesmo ocorreu com outras duas proteínas, de 70 e 79 kDa, fosforidadas em resíduos de tirosina. Concluímos que a glicose em altas concentrações reprime a proliferação celular e o sistema de síntese de catecolaminas em consequência da modificação dos processos de sinalização celular. Sugere-se que a proteína de 43 kDa é uma proteína quinase ativada por mitógeno (MAPK).
