Biomedical subjects

M Funaba

Publications and source records attributed to M Funaba.

40 records · Page 3Linked to original sources

PubMed1993

Activin A: serum levels and immunohistochemical brain localization in rats given diets deficient in L-lysine or protein.

When a L-lysine (Lys)-deficient diet is given to rats, Lys in plasma and brain declines and rats will then select a Lys solution from among other L-amino acids (AAs). The recording of single-unit activity in the lateral hypothalamic area of these rats suggested that neural plasticity occurred, specifically responding to the deficient nutrient, Lys, centrally and during ingestion of AA. Possible neurotrophic factors in serum from rats with or without deficiency of either protein or Lys was assayed by Hydra japonica. An increase in serum inhibin and activin A was observed in rats fed a Lys-sufficient and nonprotein diet, respectively. However, serum activin A-like activity was severely suppressed under Lys deficiency. Additionally, the immunohistochemical distribution of activin A in the brain was found in the nucleus tractus solitarius, the area postrema, and the arcuate nucleus. These facts indicate that ingestion of Lys-deficient or nonprotein diet caused a change in serum levels of activin A as a possible neurotrophic factor. This release may elicit plasticity in the sensitivity of neurons to deficient AA in the nuclei that could selectively drive ingestive behavior for its particular AA (e.g., Lys) to maintain AA homeostasis.

Activins↗

PubMed1990

Effects of a high protein diet on bone formation and calcium metabolism in rats.

The effects of a high protein diet on bone formation and calcium (Ca) metabolism were evaluated in rats using an ectopic endochondral bone induction model. A control diet (18% casein) or a high protein diet (18% casein + 20% lactalbumin) was given to 50-day-old rats. Ten days after the feeding of the experimental diet, rats were intramuscularly implanted with demineralized bone powder (day 0). On day 14 and day 21, the implanted bone powder was harvested, and blood and urine samples were also obtained. Urinary Ca excretion was not increased on day 12-14; however, it was elevated on day 19-21 in rats fed the high protein diet compared with rats fed the control diet. The high protein diet remarkably stimulated urinary sulfate excretion in both sampling periods, which reflected dietary sulfur-containing amino acids contents. Also, rats fed the high protein diet exhibited a decrease in serum Ca concentrations. There was little difference in Ca contents and the activities of alkaline phosphatase and acid phosphatase in the implants between control group and high protein diet group on day 14 and day 21. Histological examination in the implanted demineralized bone powder on day 14 indicated only cartilage in rats fed the high protein diet in contrast to the occurrences of osteogenesis and remodeling in those fed the control diet. Retarded bone formation in rats fed the high protein diet might be owing to, in part at least, a restricted amount of Ca utilized at the stage of cartilage calcification.

Acid Phosphatase↗

PubMed1989

Effects of high protein diet and sodium bicarbonate supplementation on calcium metabolism in rats.

This study was conducted to determine the effect of a high protein diet on calcium metabolism in rat. Wistar strain male rats (50 days old) were divided into 5 groups (day 0): control diet (18% casein); high protein diet (18% casein +20% lactalbumin); high protein and 0.1% sodium bicarbonate diet; high protein and 0.2% sodium bicarbonate diet; and high protein and 0.4% sodium bicarbonate diet. On days 0, 1, 3, 5, 7, 9, urine samples were collected and, at the same time, feces were collected from half of the animals in each group. Urinary titratable acidity (TA-HCO3-), ammonium ion (NH4+), and net acid excretion (NAE) were measured as an index of acid-base balance in rat body. Urinary volume was rapidly increased and the increase of urinary volume continued throughout the study in rats fed the high protein diet. Urinary excretions of calcium and phosphorus were increased after day 3 and day 1, respectively, in rats fed the high protein diet. The high protein diet depressed calcium absorption and elevated phosphorus absorption from the digestive tract in rats fed the high protein diet. The high protein diet decreased TA-HCO3-, which was closely correlated with the decrease of NAE. Sodium bicarbonate supplementation to the high protein diet had little effect on urinary calcium excretion and NAE. This study suggested that there was no relationship between metabolic acidosis and hypercalciuria in rats fed the high protein diet.

Acidosis↗

PubMed1987

Effect of thyroxine injection on bone growth in malnourished rats at different growth stages.

This study investigated the role of thyroxine on bone growth by injecting it into malnourished weaned and suckling rats. Weaned rats were fed a normal diet or a low-protein, low-energy diet, and injected with saline or thyroxine (5 micrograms/100 g BW) for 22 days. Suckling pups were injected with saline or 2 micrograms of thyroxine, and reared by dams fed a normal diet or a low-protein diet for 15 days. Thyroxine injection decreased body weight gain in both growth stages. Bone length, width and weight were not affected by thyroxine injection in weaned rats. Thyroxine injection increased femur length and tail growth, but did not change bone width in suckling rats. The epiphyseal growth plate and zone of hypertrophic cartilage cells were thinner in malnourished rats than in normal rats at both growth stages, but the number of proliferating chondrocytes was greater in suckling rats that received thyroxine injections than in those that received saline injections. The disappearance of trabeculae was observed in both normal and malnourished weaned rats upon thyroxine injection. These results suggested that retarded bone growth due to malnutrition might be independent of thyroid function in both growth stages.

Animals↗