Yuki Okabe

Intragastric administration of capsiate, a transient receptor potential channel agonist, triggers thermogenic sympathetic responses

The sympathetic thermoregulatory system controls the magnitude of adaptive thermogenesis in correspondence with the environmental temperature or the state of energy intake and plays a key role in determining the resultant energy storage. However, the nature of the trigger initiating this reflex arc remains to be determined. Here, using capsiate, a digestion-vulnerable capsaicin analog, we examined the involvement of specific activation of transient receptor potential (TRP) channels within the gastrointestinal tract in the thermogenic sympathetic system by measuring the efferent activity of the postganglionic sympathetic nerve innervating brown adipose tissue (BAT) in anesthetized rats. Intragastric administration of capsiate resulted in a time- and dose-dependent increase in integrated BAT sympathetic nerve activity (SNA) over 180 min, which was characterized by an emergence of sporadic high-activity phases composed of low-frequency bursts. This increase in BAT SNA was abolished by blockade of TRP channels as well as of sympathetic ganglionic transmission and was inhibited by ablation of the gastrointestinal vagus nerve. The activation of SNA was delimited to BAT and did not occur in the heart or pancreas. These results point to a neural pathway enabling the selective activation of the central network regulating the BAT SNA in response to a specific stimulation of gastrointestinal TRP channels and offer important implications for understanding the dietary-dependent regulation of energy metabolism and control of obesity.

Higher bioavailability of isoflavones after a single ingestion of aglycone‐rich fermented soybeans compared with glucoside‐rich non‐fermented soybeans in Japanese postmenopausal women

BACKGROUND There have been conflicting study results concerning how the food matrix affects the bioavailability of isoflavone aglycone and glucoside. In this study the bioavailability of isoflavones after a single ingestion of aglycone-rich fermented soybeans (Fsoy) and glucoside-rich non-fermented soybeans (Soy) was compared. Eleven healthy postmenopausal Japanese women were recruited for a randomised, double-blind, crossover trial and consumed Fsoy or Soy powder dissolved in hot water. Blood samples were collected 0, 1, 2, 3, 4, 6, 8, 12 and 24 h and urine samples from 0 to 48 h after ingestion of the powders. The Fsoy and Soy powders ingested had the same total isoflavone content (95 µmol), but the former was rich in aglycone (90.6 µmol) while the latter was rich in glucoside (81.9 µmol). RESULTS Serum concentrations of total isoflavones after 1-4 h were significantly higher in the Fsoy group than in the Soy group. The Fsoy group showed significantly higher maximum concentration (Cmax: 2.79 ± 0.13 vs 1.74 ± 0.13 µmol L(-1) ) and area under the curve (AUC(0-24 h) : 23.78 ± 2.41 vs 19.95 ± 2.03 µmol day L(-1) ) and lower maximum concentration time (Tmax: 1.00 ± 0.00 vs 5.00 ± 0.67 h) compared with the Soy group. The cumulative urinary excretion of total isoflavones after 2 h was significantly higher in the Fsoy group than in the Soy group. Individual isoflavones (daidzein, genistein and glycitein) showed similar trends to total isoflavones. Equol (a metabolite from daidzein) did not differ between the two groups. CONCLUSION The results of this study demonstrated that the isoflavones of aglycone-rich Fsoy were absorbed faster and in greater amounts than those of glucoside-rich Soy in postmenopausal Japanese women.

Isoflavones as Putative Anti‐aging Food Factors in Asia and Effects of Isoflavone Aglycone‐rich Fermented Soybeans on Bone and Glucose Metabolisms in Post‐menopausal Women

Objective:  Since soy isoflavone intake, high in Japanese and Asian populations was epidemiologically associated with lower risks of cardiovascular diseases(CVD), we focused on soy isoflavone effects on other risks of lifestyle‐related diseases and investigated whether or not the intake of isoflavone aglycone‐rich fermented soybeans affected bone and glucose metabolisms in post‐menopausal women.