RESUMO
The state of somatic energy stores in metazoans is communicated to the brain, which regulates key aspects of behaviour, growth, nutrient partitioning and development1. The central melanocortin system acts through melanocortin 4 receptor (MC4R) to control appetite, food intake and energy expenditure2. Here we present evidence that MC3R regulates the timing of sexual maturation, the rate of linear growth and the accrual of lean mass, which are all energy-sensitive processes. We found that humans who carry loss-of-function mutations in MC3R, including a rare homozygote individual, have a later onset of puberty. Consistent with previous findings in mice, they also had reduced linear growth, lean mass and circulating levels of IGF1. Mice lacking Mc3r had delayed sexual maturation and an insensitivity of reproductive cycle length to nutritional perturbation. The expression of Mc3r is enriched in hypothalamic neurons that control reproduction and growth, and expression increases during postnatal development in a manner that is consistent with a role in the regulation of sexual maturation. These findings suggest a bifurcating model of nutrient sensing by the central melanocortin pathway with signalling through MC4R controlling the acquisition and retention of calories, whereas signalling through MC3R primarily regulates the disposition of calories into growth, lean mass and the timing of sexual maturation.
Assuntos
Desenvolvimento Infantil/fisiologia , Estado Nutricional/fisiologia , Puberdade/fisiologia , Receptor Tipo 3 de Melanocortina/metabolismo , Maturidade Sexual/fisiologia , Adolescente , Idoso de 80 Anos ou mais , Animais , Criança , Ciclo Estral/genética , Ciclo Estral/fisiologia , Feminino , Homozigoto , Humanos , Hipotálamo/citologia , Hipotálamo/fisiologia , Fator de Crescimento Insulin-Like I/metabolismo , Masculino , Melanocortinas/metabolismo , Menarca/genética , Menarca/fisiologia , Camundongos , Fenótipo , Puberdade/genética , Receptor Tipo 3 de Melanocortina/deficiência , Receptor Tipo 3 de Melanocortina/genética , Maturidade Sexual/genética , Fatores de Tempo , Aumento de PesoRESUMO
BACKGROUND: Several observational studies have shown association between diet quality and depression, but few studies have explored the interrelationship between these variables. OBJECTIVE: The aim of this study was to assess the interrelationship between diet quality and depressive symptoms in elderly. DESIGN: Cross-sectional study. SETTING: Population based. PARTICIPANTS: 1,378 elderly in the city of Pelotas, Brazil. MEASUREMENTS: The diet quality was assessed by a short food frequency questionnaire and the prevalence of depressive symptoms was estimated by the abbreviated Brazilian version of the Geriatric Depression Scale (GDS). The association between diet quality and depressive symptoms was assessed using logistic regression. RESULTS: The prevalence of depressive symptoms was 15.3%. Elderly with low-quality diet were more likely to experience depressive symptoms, and the association was almost twice higher in males than in females (men OR = 3.8, 95% CI 1.4, 10.6; women OR = 2.1, 95% CI: 1.4, 3.3). On the other hand, depressive elderly had higher odds of consuming a low-quality diet (OR 2.4, 95% CI: 1.7, 3.8). LIMITATIONS: Self-reported data and cross-sectional design limit our conclusions. CONCLUSIONS: The choice of a low-quality diet was associated to a higher risk of depressive symptoms in elderly, and vice-versa. These results highlight the importance of encouraging the choice of healthy food habits, especially in depressed elderly, in order to promote healthy aging.