Contribution of polymorphisms in the LEP, LEPR and RETN genes on serum leptin and resistin levels in young adults from Mexico.

Polymorphisms in the LEP (G-2548A and A19G), LEPR (A326G, A668G and G3057A) and RETN (C-420G and G+62A) genes were documented according to their association with alterations in biochemical parameters such as glucose, insulin and lipid profiles, along with serum leptin and resistin concentrations. The aim of the study was to establish any contribution of the G-2548A and A19G polymorphisms of the LEP gene, the A326G, A668G and G3057A polymorphisms of the LEPR gene, and the C-420G and G+62A polymorphisms of the RETN gene to serum leptin and resistin levels in Mexican young adults. Clinical and biochemical variables, serum leptin and resistin levels, and genotype profiles were analysed in 66 Mexican young adults. Seven polymorphisms in the LEP, LEPR and RETN genes were genotyped using polymerase chain reaction-restriction fragment length polymorphisms analysis. Individuals carrying allele 3057A of the G3057A polymorphism in the LEPR gene showed significantly higher leptin concentrations than those bearing the genotype G/G (43.78 ± 39.11 vs 28.20 ± 14.12 ng/mL; p = 0.021). There were no associations of serum leptin or resistin levels according to the genotype of the other six analysed polymorphisms. Our results suggest that the allele 3057A of the LEPR G3057A polymorphism contributes to increased serum leptin levels in Mexican young adults.

[The effects of the social environment on the brain]. / Efectos cerebrales del medio ambiente social.

AIMS: This work analyses the main studies dealing with the mechanisms by which the brain is altered by chronic stress and the impact of social stimuli on the activation of these mechanisms, which can lead to behavioural disorders and cognitive impairment in communities of mammals. DEVELOPMENT: The physiological and hormonal responses triggered as a response to stress are linked to alterations in certain areas of the brain and more particularly in the hippocampus. These mechanisms include hyperactivity of the hypothalamus-pituitary-adrenal axis, raised levels of corticosteroids and excitatory amino acids, neurotoxicity due to intracellular accumulation of calcium, apoptosis and a number of factors having to do with the immunological system. Most of these studies have involved the exogenous application of supraphysiological levels of corticosteroids or challenging the individual with stimuli that do not properly belong to their natural surroundings. Nevertheless, it is also possible that these mechanisms are triggered by aversive social stimuli from the natural environment, such as confrontation, establishing hierarchies, neglect and social evaluation. It has been proved that social stress has important effects on conduct and health, especially with regard to the structural and functional integrity of the brain. CONCLUSIONS: Social stress can trigger important alterations in the nervous system of individuals exposed to it and these changes can manifest themselves as varying types of disorders affecting conduct and the cognitive skills. Nevertheless, not all natural surroundings give rise to these adverse effects, as balanced communities offer their members support, protection and a series of other advantages.

Efectos cerebrales del medio ambiente social / The effects of the social environment on the brain

Objetivo. El presente trabajo analiza los principales estudios sobre los mecanismos de alteración cerebral resultantes del estrés crónico y el impacto de los estímulos de tipo social sobre la activación de estos mecanismos, de lo que pueden resultar alteraciones conductuales y déficit cognitivos en las comunidades de mamíferos. Desarrollo. Las respuestas hormonal y fisiológica frente al estrés están vinculadas con alteraciones de algunas áreas cerebrales, especialmente el hipocampo. Entre estos mecanismos están: hiperactividad del eje hipotálamo-hipófisis-adrenal, elevación de la concentración de los corticosteroides y los aminoácidos excitatorios, neurotoxicidad por acumulación intracelular de calcio, apoptosis y algunos factores del sistema inmunológico. La mayoría de estos estudios han utilizado la aplicación exógena de concentraciones suprafisiológicas de corticosteroides o la confrontación del individuo con estímulos ajenos a su ambiente natural. Sin embargo, posiblemente, esos mecanismos también pueden activarse por la estimulación social aversiva del medio natural, como confrontación, establecimiento de jerarquías, abandono y evaluación social. Se ha demostrado que el estrés social tiene efectos importantes sobre el comportamiento y la salud, especialmente sobre la integridad estructural y funcional cerebral. Conclusiones. El estrés social provoca alteraciones importantes en el sistema nervioso de los individuos expuestos y estos cambios pueden manifestarse por trastornos variables del comportamiento y las habilidades cognitivas; sin embargo, no siempre resultan efectos adversos de todos los ambientes naturales, ya que las comunidades equilibradas brindan apoyo, protección y numerosas ventajas a los individuos (AU)

Aims. This work analyses the main studies dealing with the mechanisms by which the brain is altered by chronic stress and the impact of social stimuli on the activation of these mechanisms, which can lead to behavioural disorders and cognitive impairment in communities of mammals. Development. The physiological and hormonal responses triggered as a response to stress are linked to alterations in certain areas of the brain and more particularly in the hippocampus. These mechanisms include hyperactivity of the hypothalamus-pituitary-adrenal axis, raised levels of corticosteroids and excitatory amino acids, neurotoxicity due to intracellular accumulation of calcium, apoptosis and a number of factors having to do with the immunological system. Most of these studies have involved the exogenous application of supraphysiological levels of corticosteroids or challenging the individual with stimuli that do not properly belong to their natural surroundings. Nevertheless, it is also possible that these mechanisms are triggered by aversive social stimuli from the natural environment, such as confrontation, establishing hierarchies, neglect and social evaluation. It has been proved that social stress has important effects on conduct and health, especially with regard to the structural and functional integrity of the brain. Conclusions. Social stress can trigger important alterations in the nervous system of individuals exposed to it and these changes can manifest themselves as varying types of disorders affecting conduct and the cognitive skills. Nevertheless, not all natural surroundings give rise to these adverse effects, as balanced communities offer their members support, protection and a series of other advantages (AU)