Effects of Fish Oil with Heat Treatment on Obesity, Inflammation, and Gut Microbiota in Ovariectomized Mice

Background/Objectives: Menopause induces substantial metabolic changes, including a reduction in metabolic rate and an elevated risk of developing metabolic diseases. Fish oil (FO) supplementation has been shown to ameliorate menopause-associated metabolic risks. Hyperthermia treatment (HT) has recently gained attention for its potential to improve metabolic and immune health. However, it remains to be determined whether HT can confer metabolic benefits comparable to those of FO supplementation or enhance the metabolic benefits of FO supplementation. This study aims to delineate the distinctive and collaborative effects of HT and FO supplementation in mitigating menopause-associated metabolic dysfunction. Methods: Female C57BL/6 ovariectomized (OVX) mice were randomly assigned to four groups (n = 12/group) to evaluate the individual and combined effects of FO supplementation (5% w/w) and HT treatment. For HT, whole-body heat exposure was conducted at 40-41 °C for 30 min, 5 days per week. After 12 weeks, animals were used to evaluate the changes in glucose and lipid metabolism, obesity outcome, and inflammatory markers. The gut microbiome analysis was conducted from cecal content by 16S rRNA sequencing. Acute inflammation was induced by lipopolysaccharide (LPS) injection to evaluate inflammatory responses. Results: HT alone distinctively reduced weight gain, lowered core body temperature, and attenuated insulin resistance comparable to FO supplement in OVX mice. The collaborative effect of FO and HT was not evident in metabolic parameters but more prominent in attenuating proinflammatory responses and microbiota modulation. Conclusions: Our findings suggest that the combined treatment of FO supplementation and HT may serve as an effective strategy to mitigate menopause-associated immune susceptibility and metabolic dysfunction. These benefits are likely mediated, at least in part, through the reduction in inflammation and modulation of the gut microbiota.