Swimming reduces fatty acids-associated hypothalamic damage in mice.

The arcuate and the paraventricular and lateral hypothalamic nuclei, related to hunger and satiety control, are generally compromised by excess fatty acids. In this situation, fatty acids cause inflammation via TLR4 (toll like receptor 4) and the nuclei become less responsive to the hormones leptin and insulin, contributing to the development of obesity. In this work, these nuclei were analyzed in animals fed with high-fat diet and submitted to swimming without and with load for two months. For this, frontal sections of the hypothalamus were immunolabelled with GFAP (glial fibrillary acidic protein), synaptophysin, IL-6 (interleukin 6) and TLR4. Also, proteins extracted from the hypothalamus were analyzed using Western blotting (GFAP and synaptophysin), fluorometric analysis for caspases 3 and 7, and CBA (cytometric bead array) for Th1, Th2, and Th17 profiles. The high-fat diet significantly caused overweight and, in the hypothalamus, decreased synapses and increased astrocytic reactivity. The swimming with load, especially 80 % of the maximum load, reduced those consequences. The high-fat diet increased TLR4 in the arcuate nucleus and the swimming exercise with 80 % of the maximum load showed a tendency of reducing this expression. Swimming did not significantly influence the inflammatory or anti-inflammatory cytokines in the hypothalamus or in plasma. The high-fat diet in sedentary animals increased the expression of caspases 3 and 7 and swimming practice reduced this increment to levels compatible with animals fed on a normal diet. The set of results conclude that the impact of swimming on the damage caused in the hypothalamus by a high-fat diet is positive. The different aspects analyzed in here point to better cellular viability and conservation of the synapses in the hypothalamic nuclei of overweight animals that practiced swimming with a load.

Palmitate treated-astrocyte conditioned medium contains increased glutathione and interferes in hypothalamic synaptic network in vitro.

Excessive fat consumption increases the level of fatty acids (FAs) in the blood, which reach the hypothalamus and damage the circuit related to energy balance. In the present study, we used palmitate in a primary culture of purified astrocytes to mimic the fat-rich environment found in obesity. Our results showed increased glial fibrillary acidic protein (GFAP) reactivity in hypothalamic astrocytes compared to cortical astrocytes. In addition, palmitate-treated astrocytes showed no significant changes in cytokine expression and an upregulation of glutathione in the culture medium that may serve as an intrinsic neuroprotective property against excess FA. Additionally, purified hypothalamic neurons were incubated with palmitate-treated astrocyte-conditioned medium (MPAL). MPAL treated-neurons exhibited a reduction in excitatory synapses and enhanced neuritogenesis. Our results suggest that hypothalamic astrocytes react to palmitate differently than cortical astrocytes and influence the behavior of the neural network related to energy balance. Our work brings a better understanding of the interactions among hypothalamic neurons in a high FA environment, similarly to obesity induced by a high-fat diet.

Physiological adaptations induced by swimming in mice fed a high fat diet.

This study examined physiological variables of animals fed with a high-fat diet (HFD) or with a normal diet (ND) subjected to swimming at low and moderate level. Over 16 weeks, a group of animals was fed with HFD or ND, and at the 8 weeks, they started swimming with 50% or 80% of the maximum load achieved in the progressive work test. Weekly, body weight and the amount of ingested food were registered. The glycemic level was measured at the beginning, middle and at the end of the experiment. Adipose tissue, gastrocnemius muscles and hearts were collected for morphometry. The results showed that the animals fed an HFD had a minor caloric intake; however, the HFD increased body weight and adiposity, likely causing cardiac hypertrophy and an increase in the glycemic level. In this context, swimming with an 80% load contributed positively to weight control, adiposity, glycemic level, to control cardiac hypertrophy and induce hypertrophy in the gastrocnemius muscle. All parameters assessed showed better results for the ND animals. Therefore, the importance of fat consumption was emphasized in relation to obesity onset. The practice of swimming with an 80% load produced greater benefits than swimming with a 50% load for overweight treatment.