Role of insulin resistance and diet in acne.

There is increasing evidence in support of the interplay of growth hormone (GH), insulin, and insulin-like growth factor-1 (IGF-1) signaling during puberty, which have a causal role in pathogenesis of acne by influencing adrenal and gonadal androgen metabolism. Milk consumption and hyperglycemic diets can induce insulin and IGF-1-mediated PI3K ⁄ Akt-activation inducing sebaceous lipogenesis, sebocyte, and keratinocyte proliferation, which can aggravate acne. Occurence of acne as part of various syndromes also provides evidence in favor of correlation between IGF-1 and acne.

Participación del sistema endocanabinoide en el desarrollo de obesidad / A role for the endocannabinoid system in obesity

Endocannabinoids are the endogenous ligands for the cannabinoid receptors type 1 and 2. These membrane receptors are responsible for the psychotropic effects of Cannabis Sativa, when bound to its active component known as (-)-Δ9-tetrahydro-cannabinol. Cannabinoid receptors, endocannabinoids and the enzymes catalyzing their biosynthesis and degradation, constitute the endocannabinoid system (ECS), which has a remarkable role controlling energy balance, both at central nervous system and peripheral tissues. The ECS regulates food ingestion by stimulating a network of orexigenic neurons present in the hypothalamus and reinforcing motivation and reward to food consumption in the nucleus accumbens. Regarding peripheral tissues, this system controls lipid and glucose metabolism at different levels, reduces energy expenditure and leads energy balance to fat storage. Metabolic alterations, includ-ing excessive accumulation of abdominal fat, dyslipidaemia and hyperglicaemia, are suggested to be associated to a hyperactivated ECS. Since obesity is one of the major health problems in modern societies, in this review we discuss the role of the endocannabinoid system in metabolic pathways associated to control mechanisms of energy balance and its involvement in overweight and obesity. In addition, we also discuss therapeutic possibilities and emergent problems due to cannabinoid receptor type 1 antagonism utilized as treatment for such alterations.

Differences in lipogenesis and lipolysis in obese and non-obese adult human adipocytes

It has been proposed that differences in adipocyte function and/or metabolism between obese and lean individuáis may manifest themselves in functional adipose tissue abnormalities that lead to metabolic disorders in obesity. We studied lipogenesis and lipolysis of omental adipocytes from obese (OB) and non-obese (NOB) humans. The specific activity of the lipogenic marker enzyme G3PDH was 50 percent lower in total adipocytes of OB compared to that of NOB subjects. Omental adipocytes from OB subjects also had lower basal lipolytic levéis, and a lower lipolytic response to p-adrenergic stimulus. Cholesterol depletion of adipocyte plasma membrane using methyl β-cyclodextrin caused a lipolytic effect on adipocytes of both groups together, but when obese and lean subjects were analyzed separately, the response was significant only in the obese. We present evidence of a different lipogenic and lipolytic profile in obese individuáis' omental adipocytes, and propose a relevant role of plasma membrane cholesterol, where the impact of its removal in OB and NOB adipocyte lipolysis differs.

O tecido adiposo como órgão endócrino: da teoria à prática: [revisão] / Adipose tissue as an endocrine organ: from theory to practice: [review]

OBJETIVOS Mostrar os avanços na pesquisa sobre o papel fisiológico do tecido adiposo branco, ressaltando o seu papel endócrino em processos inflamatórios, no comportamento alimentar, na sensibilização à insulina e na modulação do processo de aterogênese. Abordar o potencial papel do tecido adiposo como fonte de células-tronco para regeneração de tecidos, com especial ênfase para a adipogênese e suas conseqüências para a geração de obesidade. FONTES DE DADOS: Informações importantes constantes da literatura científica foram compiladas de modo a que esta leitura contenha uma síntese esclarecedora dos aspectos mencionados acima. SÍNTESE DOS DADOS:O tecido adiposo possui, além das suas funções clássicas como principal estoque de energia metabólica, suprindo as necessidades energéticas em períodos de carência mediante a lipólise, a capacidade de sintetizar e secretar vários hormônios, as adipocinas. Estas agem em diversos processos, como o controle da ingestão alimentar (leptina) e o controle da sensibilidade à insulina e de processos inflamatórios (TNF-alfa, IL-6, resistina, visfatina, adiponectina). Além disso, como o tecido adiposo contém também células indiferenciadas, tem a habilidade de gerar novos adipócitos, regenerando o próprio tecido (adipogênese), bem como originar outras células (mioblastos, condroblastos, osteoblastos), fato este que tem grande potencial terapêutico em futuro não muito distante. CONCLUSÃO: Amplia-se o leque de possibilidades funcionais do tecido adiposo. A compreensão dessas potencialidades pode fazer deste tecido o grande aliado no combate de moléstias que atualmente vêm assumindo proporções epidêmicas (obesidade, diabetes melito, hipertensão arterial e arteriosclerose), nas quais o tecido adiposo ainda é tido como um grande vilão.

OBJECTIVES: To describe the advances in research into the physiological role of white adipose tissue, with emphasis on its endocrinal role in inflammatory processes, feeding behavior, insulin sensitization and modulation of the atherogenetic process. To deal with the potential role of adipose tissue as a source of stem cells for regeneration of tissues, with special emphasis on adipogenesis and its consequences for development of obesity. SOURCES: Important information was compiled from the scientific literature in order that this analysis contains an explanatory synthesis of the aspects mentioned above. SUMMARY OF THE FINDINGS In addition to its classical functions as primary metabolic energy store, meeting energy requirements during periods of deprivation by means of lypolisis, adipose tissue also has the capacity to synthesize and secrete a variety of hormones - the adipokines. These are active in a range of processes, such as control of nutritional intake (leptin) and control of sensitivity to insulin and inflammatory processes (TNF-alpha, IL-6, resistin, visfatin, adiponectin). Furthermore, since adipose tissue also contains undifferentiated cells, it has the ability to generate new adipocytes, regenerating its own tissue (adipogenesis), and also the ability to give rise to other cells (myoblasts, chondroblasts, osteoblasts), which has great therapeutic potential in the not-too-distant future. CONCLUSIONS: The range of functional possibilities of adipose tissue has widened. An understanding of these potentials could make this tissue a great ally in the fight against conditions that are currently assuming epidemic proportions (obesity, diabetes mellitus, arterial hypertension and arteriosclerosis) and in which adipose tissue is still seen as the enemy.