Hirotada Tsujii

Genetic analysis for diabetes in a new rat model of nonobese type 2 diabetes, Spontaneously Diabetic Torii rat.

The Spontaneously Diabetic Torii (SDT) rat has recently been established as a new rat model of nonobese type 2 diabetes. In this study, we characterized diabetic features in SDT rats, and performed quantitative trait locus (QTL) analysis for glucose intolerance using 319 male (BNxSDT)xSDT backcrosses. Male SDT rats exhibited glucose intolerance at 20 weeks, and spontaneously developed diabetes with the incidence of 100% at 38 weeks, and glucose intolerance is well associated with the development of diabetes. The QTL analysis identified three highly significant QTLs (Gisdt1, Gisdt2, and Gisdt3) for glucose intolerance on rat chromosomes 1, 2, and X, respectively. The SDT allele for these QTLs significantly exacerbated glucose intolerance. Furthermore, synergistic interactions among these QTLs were detected. These findings indicate that diabetic features in SDT rats are inherited as polygenic traits and that SDT rats would provide insights into genetics of human type 2 diabetes.

Karaya root saponin exerts a hypocholesterolemic response in rats fed a high-cholesterol diet

Different sources of saponins are known to have hypocholesterolemic activity with varying degrees of efficacy. We hypothesize that karaya root saponin would efficiently reduce cholesterol. The aim of this study is to examine the comparative hypocholesterolemic effect of karaya root saponin in rats fed a high-cholesterol diet. Sixty male Wister-Imamichi rats were divided into 5 groups of 12 rats each constituting of the following: control group, soybean saponin-supplemented group, karaya root saponin-supplemented group, quillaja saponin-supplemented group, and tea saponin-supplemented group. Compared with the control diet, both the karaya root- and quillaja saponin-supplemented diets significantly reduced (P < .05) serum cholesterol and atherogenic index. Karaya root saponin significantly increased the serum high-density lipoprotein cholesterol, high-density lipoprotein cholesterol/cholesterol ratio, and fecal cholesterol concentrations (P < .05). The triacylglycerol concentration was significantly reduced only in the quillaja saponin-supplemented rats (P < .05). All the tea, soybean, karaya root, and quillaja saponins significantly reduced low-density lipoprotein cholesterol, and the greatest reduction was observed with karaya root saponin. Highest fecal bile acid concentration was found with quillaja saponin, whereas highest liver bile acid concentration was observed with karaya root saponin-supplemented rats (P < .05). These results collectively suggest that karaya root saponin can efficiently reduce serum cholesterol concentration in rats.

Effect of fatty acids on boar sperm motility, viability and acrosome reaction

AimThe present study was undertaken to determine which fatty acids improve motility viability and increase acrosome reaction (AR) in boar spermatozoa.MethodsBoar spermatozoa were washed, swum-up and incubated at 37°C for 4 h in TALP medium supplemented with myristic, palmitic, stearic, lignoceric, oleic, linoleic, arachidonic, docosahexaenoic and palmitoleic acid. Sperm motility, viability and AR were evaluated during 4 h of incubation.ResultsResults show that oleic and linoleic acid significantly improved (P < 0.05) the motility and viability of boar spermatozoa. The AR was significantly improved (P < 0.05) by oleic and arachidonic acid in almost all incubation periods. When combinations of oleic, linoleic and arachidonic acid were studied for motility, viability and AR, it was found that oleic plus linoleic acid significantly increased (P < 0.05) motility, whereas arachidonic plus oleic acid significantly increased (P < 0.05) AR.ConclusionUnsaturated fatty acids, especially arachidonic acid, can improve boar sperm motility and AR. A combination of arachidonic and oleic acid is important for inducing boar sperm AR.

Dietary Karaya Saponin and Rhodobacter capsulatus Exert Hypocholesterolemic Effects by Suppression of Hepatic Cholesterol Synthesis and Promotion of Bile Acid Synthesis in Laying Hens.

This study was conducted to elucidate the mechanism underlying the hypolipidemic action of karaya saponin or Rhodobacter (R.) capsulatus. A total of 40 laying hens (20-week-old) were assigned into four dietary treatment groups and fed a basal diet (as a control) or basal diets supplemented with either karaya saponin, R. capsulatus, or both for 60 days. The level of serum low-density-lipoprotein cholesterol and the levels of cholesterol and triglycerides in the serum, liver, and egg yolk were reduced by all the supplementations (P < .05). Liver bile acid concentration and fecal concentrations of cholesterol, triacylglycerol, and bile acid were simultaneously increased by the supplementation of karaya saponin, R. capsulatus, and the combination of karaya saponin and R. capsulatus (P < .05). The supplementation of karaya saponin, R. capsulatus, and the combination of karaya saponin and R. capsulatus suppressed the incorporation of 14C from 1-14C-palmitic acid into the fractions of total lipids, phospholipids, triacylglycerol, and cholesterol in the liver in vitro (P < .05). These findings suggest that the hypocholesterolemic effects of karaya saponin and R. capsulatus are caused by the suppression of the cholesterol synthesis and the promotion of cholesterol catabolism in the liver.

Effect of dietary karaya saponin on serum and egg yolk cholesterol in laying hens

1. The objective of the study was to investigate the effect of dietary karaya saponin on cholesterol deposition in laying hens. 2. A total of 40 Boris Brown hens were randomly assigned at 20 weeks of age to 4 treatment groups and fed on diets supplemented with 0 (control), 25, 50 or 75 mg/kg karaya saponin for an 8-week experimental period. 3. After 8 weeks of dietary supplementation, karaya-saponin-treated groups had significantly lower serum cholesterol (23·0%) and triglycerides but increased high density lipoproteins cholesterol concentration than controls, irrespective of karaya saponin content in the diet. Egg yolk cholesterol and triglycerides were also significantly reduced by dietary karaya saponin. Hepatic cholesterol and triglycerides were significantly reduced by karaya saponin but bile acids concentration in the faeces and liver were significantly increased by karaya saponin. The concentrations of oleic, linoleic and linolenic acids in the yolk were greater in hens receiving karaya saponin than in controls. Karaya saponin significantly increased egg production, feed efficiency and yolk colour compared with controls. Karaya saponin tended to increase egg weight, feed consumption, Haugh units, albumen weight and yolk index. 4. In conclusion, karaya saponin is a potential agent for reducing yolk cholesterol concentration together with an overall increase of production performance and improvement in egg quality.

Effect of amino acids and dipeptides on accumulation of ammonia in the medium during in vitro maturation and fertilization of porcine oocytes

AimThe present study was designed to investigate the effect of amino acids and their dipeptides on the accumulation of ammonia in the medium during in vitro maturation (IVM) and in vitro fertilization (IVF) of porcine oocytes.MethodsThe IVM and IVF media were modified North Carolina State University-37 solution and modified Tyrode’s albumin lactate pyruvate, respectively. Porcine oocytes were matured in IVM medium containing 75–2400 μmol ammonia. Amino acids (1.0 mmol) or their dipeptides (2.0 mmol) related to the urea cycle were added individually to the IVM and IVF media containing 300 μmol ammonia. Oocyte maturation and fertilization were assessed using acetic-orcein staining, and the accumulation of ammonia in the media was measured using the indophenol method.ResultsPercentages of metaphase II (MII) were adversely affected (P < 0.05) by ≥300 μmol concentrations of ammonia in the IVM medium. In the presence of 300 μmol ammonia in the IVM and IVF media, glutamic acid, L-alanyl-L-glutamine (AlaGln), L-glycyl-L-glutamine (GlyGln) and AlaGln + GlyGln showed the highest rate (P < 0.05) of MII, monospermic fertilization, and the lowest rate (P < 0.05) of ammonia accumulation in the media.ConclusionAlaGln and GlyGln in IVM and IVF media were more stable and effective than the individual amino acids in reducing the accumulation of ammonia, and increased the rate of porcine oocyte MII and monospermic fertilization in vitro.

Effects of dopamine d2 receptor agonists in a pituitary transplantation-induced hyperprolactinaemia/anovulation model in rats.

1. In the present study, we investigated the effects of hyperprolactinaemia, induced by transplantation of anterior pituitary glands under the kidney capsule in female rats, on the relationship between serum and pituitary concentrations of the gonadotropins and on the oestrous cycle.

Effects of relaxin and IGF-I on capacitation, acrosome reaction, cholesterol efflux and utilization of labeled and unlabeled glucose in porcine spermatozoa

AimRelaxin and insulin-like growth factor (IGF)-I have pronounced effects on the male and female reproductive tracts. The aim of this study was to investigate the effects of relaxin and IGF-I on the motility, capacitation, acrosome reaction, cholesterol efflux and utilization of glucose in porcine spermatozoa.MethodsSwim-up separated spermatozoa that had been washed twice were incubated at 37°C for 1 or 4 h in modified Tyrode’s albumin lactate pyruvate (mTALP) medium supplemented without (control) or with relaxin (20 ng/mL) or IGF-I (20 ng/mL) or both (10 + 10 ng/mL).ResultsProgressive motility and the induction rate of capacitation and acrosome reaction were increased (P < 0.05) by relaxin and IGF-I alone or in combination, especially after 4 h of incubation. Relaxin alone or combined with IGF-I enhanced (P < 0.05) the cholesterol efflux after 4 h, whereas IGF-I alone did not show any significant effect on the cholesterol efflux compared with the control at any time point. The utilization rates of labeled and unlabeled glucose increased (P < 0.05) in spermatozoa incubated with relaxin or IGF-I alone or in combination compared with the control.ConclusionThus, supplementation of relaxin alone or combined with IGF-I into the medium possibly plays a beneficial role in porcine spermatozoal prefertilization events in vitro.

Effect of fatty acids bound to bovine serum albumin-V on acrosome reaction and utilization of glucose in boar spermatozoa

AimThe present study has been designed with the objective of determining if fatty acids bound to bovine serum albumin-V (BSA-V) can improve motility, viability, and increase acrosome reaction (AR) and utilization of glucose in boar spermatozoa.MethodsBoar spermatozoa were washed, swum-up and incubated at 37°C for 6 h in TALP medium supplemented with fatty acids bound to bovine serum albumin fraction V (BSA-V), fatty acid free BSA (BSA-FAF), polyvinyl alcohol + main fatty acids bound to BSA-V (PVA + FA) and PVA. Sperm motility, viability, AR, and the incorporation and oxidation of 14C-glucose were evaluated during 6 h of incubation.ResultsThe results show that the BSA-V was superior to BSA-FAF and PVA in improving motility and AR. Viability was significantly increased (P < 0.05) by only BSA-V compared with PVA. When the main fatty acids compound of BSA-V were added to PVA, the sperm motility, viability and AR became almost the same as with BSA-V. The rate of incorporation and oxidation of 14C-glucose were significantly increased (P < 0.05) by BSA-V compared with BSA-FAF and PVA. Fatty acids bound to BSA-V are important for improvement of sperm functions.ConclusionsThe present study postulates that fatty acids bound to BSA-V are important to acrosome reaction and the utilization of glucose in boar spermatozoa. (Reprod Med Biol 2007; 6: 109–115)

Effect of relaxin on motility, acrosome reaction and viability of cryopreserved boar spermatozoa

Background and AimsRelaxin has an important role in stimulating motility and the acrosome reaction (AR) of fresh boar spermatozoa. The objective of the present study was to determine whether relaxin can improve the motility, AR and viability of cryopreserved boar spermatozoa.MethodsCryopreserved boar spermatozoa were thawed, washed and incubated at 37°C for 4 h in modified Beltsville thawing solution supplemented with 0, 20 or 40 ng/mL relaxin. Sperm motility, AR, viability, and incorporation and oxidation of 14C-glucose were evaluated during 0–04 h of incubation.ResultsThe results show that the supplementation of relaxin (especially at 20 ng/mL) in the thawing solution improved sperm motility significantly (P < 0.05) at 1–3 h of incubation. The percentage of acrosome reacted live spermatozoa was improved significantly (P < 0.05) when the spermatozoa were treated with 20 ng/mL relaxin. Viability was not significantly (P > 0.05) improved by supplementation with relaxin. The rates of incorporation and oxidation of 14C-glucose were increased in correlation with AR up to 4 h of incubation.ConclusionWe conclude that relaxin can improve the sperm motility and AR, and enhance the glucose metabolism of cryopreserved boar spermatozoa.