Hiroaki Matsuyama

Effects of milk fermented by Lactobacillus gasseri SBT2055 on adipocyte size in rats

Despite adequate scientific evidence of the potential benefits of probiotics to human health or disease prevention, their contribution to the growth of adipose tissue remains to be established. Four-week-old male Sprague-Dawley rats were fed a diet containing skim milk (control diet) or skim milk fermented by Lactobacillus gasseri SBT2055 (LGSP diet) for 4 weeks. Their body weight gain, adipose tissue weight, adipocyte size distribution profile, blood and hepatic lipids, and serum leptin, glucose and adiponectin levels were determined. There was a significant reduction in average adipocyte size in mesenteric white adipose tissue (P = 0.004). Moreover, the rats fed the LGSP diet displayed greater numbers of small adipocytes from mesenteric and retroperitoneal adipose tissues than did those on the control diet. Whereas adiponectin concentrations did not differ between the groups, serum leptin concentrations were decreased to 32 % in the LGSP diet group compared with the control group. Concentrations of serum glucose and lipids, and liver lipids, except for the liver TAG level, were similar in the two groups. These results indicate a possible role for a fermented milk product in the regulation of adipose tissue growth.

Milk fermented by Lactobacillus gasseri SBT2055 influences adipocyte size via inhibition of dietary fat absorption in Zucker rats.

We have demonstrated previously that a diet containing skimmed milk (SM) fermented by Lactobacillus gasseri SBT2055 (LGSP) reduces adipocyte size in Sprague-Dawley rats. Two experiments were conducted to extend these observations in order to elucidate the mechanism involved. In experiment 1, lean and obese Zucker rats were fed a diet containing SM or LGSP for 4 weeks. The LGSP diet, compared with the SM diet, resulted in lowering of the mesenteric adipose tissue weight (23 %; P < 0.05), adipocyte sizes (28 %; P < 0.001) and serum leptin concentration (36 %; P < 0.05) in lean rats. Obese Zucker rats did not display such dietary effects. Only the number of smaller adipocytes was increased (P < 0.05) by the LGSP diet in the subcutaneous adipose tissue of obese rats. The LGSP diet significantly reduced the serum and hepatic cholesterol in rats. In addition, the LGSP diet led to an increased excretion of faecal fatty acids and total neutral faecal sterols in both rat strains. In experiment 2, Sprague-Dawley rats with permanent cannulation of the thoracic duct were fed either the SM or LGSP diets and their lymph was collected. The LGSP diet lowered the maximum transport rate of TAG and phospholipids. These results indicate that fermented milk regulates adipose tissue growth through inhibition at the stage of dietary fat absorption in lean Zucker rats.

Milk whey protein enhances the bone breaking force in ovariectomized rats

Abstract We studied the effects of whey protein (WP) and fractionated WP (HWP; heat-stable WP, LWP; low M.W. WP, EWP; ethanol-precipitated WP) on calcium and bone metabolism in ovariectomized (OVX) rats. Six-week-old female Sprague-Dawley rats were ovariectomized and fed a low-calcium diet (0.03% Ca, 0.3% P) for 4 weeks. The rats were divided into five groups, Cont, WP, HWP, LWP and EWP group, and were fed a Cont diet (20% casein, 0.3% Ca) or a diet (19% casein, 0.3% Ca) containing 1% WP, HWP, LWP or EWP for 4 weeks. There were no significant differences in the calcium balance, serum calcium and calcitonin levels among the experimental groups. However, serum ALP activity of the HWP and EWP groups at 14 wks. were lower than that of the Cont group. The bone breaking strength and energy of femur of the HWP, LWP and EWP groups were higher than those of the Cont group. As for the amount of calcium, phosphorus, and magnesium in the femur, there were no significant differences among the experimental groups; however, the amounts of total amino acids in the femur of the HWP, LWP and EWP groups were higher than that of the Cont group. The amounts of proline and hydroxyproline (typical amino acids of collagen) in the femur of the HWP, LWP and EWP groups were also higher than those of the Cont group. These data indicate that milk WP contains active components that influence bone metabolism in OVX rats by increasing in bone protein such as collagen and enhance the bone breaking force (strength and energy). These results suggest that the active components are existed in heatstable, low M.W. and 30–70% ethanol-precipitated fraction, respectively.

Whey protein suppresses the osteoclast-mediated bone resorption and osteoclast cell formation

Abstract Effects of whey protein on bone resorption and osteoclastic cell formation were evaluated. In the pre-existed and newly formed osteoclast, in bone resorption methods using an unfractionated bone cell culturing system, whey protein suppressed the area of pits formed by osteoclasts. In the osteoclastic cell formation method using the hemopoietic blast cell culturing system, whey protein also suppressed osteoclastic cell formation. These activities were resistant to heat when the protein was treated at 75–90°C for 10xa0min. Heat-treated whey protein was first fractionated on a Mono S column, and the active fraction (basic protein fraction) was then applied to Superose 12. The molecular weights of the active components were approximately 23xa0000 and 10xa0000xa0Da, as determined by gel filtration. The inner solution of an everted gut-sac incubated in a solution of intact basic protein (BP), pepsin-digested BP or pepsin/pancreatin-digested BP also suppressed osteoclast-mediated bone resorption. Thus, these active components can possibly be absorbed or transported by the intestines. These results showed that whey protein contains an active component that suppresses osteoclast-mediated bone resorption and osteoclastic cell formation.

Milk sphingomyelin accelerates enzymatic and morphological maturation of the intestine in artificially reared rats.

Objectives Sphingomyelin (SPM) is the dominant phospholipid, comprising 38% of total human milk phospholipids. Although little is known about the nutritional importance of SPM during the neonatal period, SPM may affect the growth and development of tissues in the newborn infant through mechanisms regulating cell proliferation and differentiation. We evaluated the effect of sphingomyelin (SPM) in artificially reared rats as a suitable model of gut maturation in the suckling infant. Methods Seven-day-old Sprague-Dawley rat pups were cannulated intragastrically and reared artificially on milk containing 0.5% SPM or 0.5% phosphatidylcholine (PC) for 1 week. Results Intestinal lactase activity in the SPM group was significantly lower than that in the control or PC group. Upon histologic examination, intestinal villi were found to be occupied with vacuolated cells in the control and the PC group, whereas the vacuolated cells were restricted to the tip of villi in the SPM group. The Auerbach nerve plexus area of the ileum in the SPM group was significantly greater, possibly due to accelerated development, than that in the control group or PC group. Conclusions The present results suggest that SPM, the dominant phospholipid in milk, plays an important role in neonatal gut maturation during the suckling period.

Milk calcium taken with cheese increases bone mineral density and bone strength in growing rats.

We investigated the calcium bioavailability of milk calcium, taken with or without cheese. Twenty-four 6-week-old male rats for a meal-feeding experiment were trained to consume an AIN-76 diet within 2 h (2 times per day) for 2 weeks. The rats were then divided into three experimental groups, each fed 2 types of experimental diets: Control group, Cheese group, and Ca-Cheese group. The rats were each alternately given 2 types of experimental diets at 2-h meal-feeding for 31 days. The breaking force and energy of the femur in the Ca-Cheese group were significantly higher than in the control group. The bone mineral density (BMD) of the lumbar spine and the femur in the Ca-Cheese group was also significantly higher than in the other two groups. These results indicate that milk calcium taken with cheese increases bone strength and BMD efficiently, results that may be useful for the prevention of osteoporosis.