Arnaud, M. | bioRxiv Science

bioRxiv2018

Prevalence of TMD and level of chronic pain in a group of Brazilian adolescents

ObjectivesTo determine the prevalence of temporomandibular disorder and associated factors in an adolescent sample from Recife, Brazil.\n\nMaterials and MethodsA cross-sectional study was conducted with 1342 adolescents aged 10-17 years. The Research Diagnostic Criteria for Temporomandibular Disorder (RDC/TMD) was used by calibrated examiners to evaluate the presence and levels of chronic pain. To evaluate the socioeconomic conditions, the Brazilian Economic Classification Criteria (CCEB) questionnaire was answered by the subjects. Data were analyzed by means of binary logistic regression in SPSS.\n\nResultsThe results showed that 33.2% of the subjects had TMD irrespective of age (p= 0.137) or economic class (p=0.507). Statistically significant associations were found between TMD and gender (p= 0.020), headache/migraine in the past six months (p=0,000) and the presence of chronic pain (p=0,000). In final model, logistic regression showed that chronic pain contributes to the presence of TMD.\n\nConclusionsThe prevalence of TMD was considered high (33.2%) and adolescents with chronic pain were more likely to have TMD.\n\nClinical RelevanceThe data contribute to the understanding of TMD among adolescents and to the development of preventive measures and polices to identify the dysfunction promptly.

epidemiology↗

bioRxiv2018

Rapid sensing of L-leucine by human and murine hypothalamic neurons: neurochemical and mechanistic insights

ObjectiveDietary proteins are sensed by hypothalamic neurons and strongly influence multiple aspects of metabolic health, including appetite, weight gain and adiposity. However, little is known about the mechanisms by which hypothalamic neural circuits controlling behavior and metabolism sense protein availability. The aim of this study is to characterize how neurons from the mediobasal hypothalamus respond to a signal of protein availability: the amino acid L-leucine.\n\nMethodsWe used primary cultures of post-weaning murine mediobasal hypothalamic neurons, hypothalamic neurons derived from human induced pluripotent stem cells, and calcium imaging to characterize rapid neuronal responses to physiological changes in extracellular L-Leucine concentration.\n\nResultsA neurochemically diverse subset of both mouse and human hypothalamic neurons responded rapidly to L-leucine. Consistent with L-leucines anorexigenic role, we found that 25% of mouse MBH POMC neurons were activated by L-leucine. 10% MBH NPY neurons were inhibited by L-leucine, and leucine rapidly reduced AGRP secretion, providing a mechanism for the rapid leucine-induced inhibition of foraging behaviour in rodents. Surprisingly, none of the candidate mechanisms previously implicated in hypothalamic leucine sensing (KATP channels, mTORC1 signaling, amino-acid decarboxylation) were involved in the acute activity changes produced by L-leucine. Instead, our data indicate that leucine-induced neuronal activation involves a plasma membrane Ca2+ channel, whereas leucine-induced neuronal inhibition is mediated by inhibition of a store-operated Ca2+ current.\n\nConclusionsA subset of neurons in the mediobasal hypothalamus rapidly respond to physiological changes in extracellular leucine concentration. Leucine can produce both increases and decreases in neuronal Ca2+ concentrations in a neurochemically-diverse group of neurons, including some POMC and NPY/AGRP neurons. Our data reveal that leucine can signal through novel mechanisms to rapidly affect neuronal activity.\n\nHighlights- A neurochemically diverse group of mouse and human hypothalamic neurons rapidly sense and respond to L-leucine\n- Leucine can produce neuronal activation or neuronal inhibition via distinct and novel Ca2+ signaling mechanisms.\n- Leucine activates 25% ARH POMC neurons\n- Leucine inhibits 10% ARH NPY/AGRP neurons and reduces AGRP secretion from fasted mediobasal hypothalamic slices

neuroscience↗