Protocol approval was obtained from the ethics committee of Toya Laboratory, HOKUDO Co. (Ref no: HKD47055). This study was conducted in accordance with the HOKUDO Animal Experiment Regulations. The following standards for the reliability of application materials were followed: Article 43 of the Pharmaceutical Affairs Enforcement Regulations (February 1, 1957: Ministry of Health and Welfare Ordinance No. 1; last revision: August 30, 2012: Ministry of Health, Labour and Welfare Ordinance No. 120).
Six-week-old Sprague Dawley (SD)/Jcl rats (Nippon Clare Co., Japan) were used in the study. At the start of the experiment, the animals weighed 188.8 to 217.3 g. Their general condition was observed at the time of arrival, and those with no abnormalities were acclimatised for about one week from the date of arrival. During the acclimation period, the animals’ general condition was observed daily, and healthy animals with no abnormalities were used for the study. These were divided into four groups (six male animals per group) using a weight stratified randomisation method so that the average weight of each group was as uniform as possible. The animals were kept in a rearing environment with a room temperature of 23 ± 2°C (acceptable limit range: 20–26°C), relative humidity of 55 ± 10% (acceptable limit range: 30–70%), and 12 hours each of light and dark (lighting hours: 7:00 a.m. to 7:00 p.m.). The rats were housed in plastic cages (W26 × D31 × H18 cm) with bedding (bedding chips, Dohoh Rika Sangyo Co., Ltd.), one animal in each cage. The cage and bedding were changed at least once a week.
The animals were fed a solid feed, CE-2 (Feed One Co., Ltd., Japan), which was less than one year old. Drinking water was ground water that was sterilised by adding sodium hypochlorite to achieve a residual chlorine level of 0.3–0.4 mg/L using a facility water steriliser (MJ25SR, Kawamoto Manufacturing Co., Ltd., Japan). The water bottles were changed at least twice a week.
The groups and doses of the test substances were as follows:
Group 1 (n = 6): Euthanised on Day 0 for baseline values
Group 2 (n = 6): Control (solvent—drinking water)
Group 3 (n = 6): AFO-202 beta glucan—200 mg/kg/day; 20 mg/ml concentration in solution
Group 4 (n = 6): N-163 beta glucan—300 mg/kg/day; 30 mg/ml concentration in solution
The dose of each test substance was determined to be equivalent to the estimated daily intake dose for humans, which is 10 g in gel form for AFO-202 beta-glucan (5 mg of active ingredient of beta-glucan per gm) and 15 g in gel form for N-163 beta-glucan (6 mg of active ingredient of beta-glucan per gm).
Because the test substances are food materials, oral administration was selected. The dosing method was gavage, which is commonly used for oral administration in rodents. The administration period was 28 days. A gastroscope (Fuchigami Kikai Co., Ltd.) and a disposable syringe (Terumo Co., Ltd.) were used to force the oral administration into the stomach once a day for 28 consecutive days. Six animals were weighed using an electronic balance (FX-1200I, A&D Co., Ltd.) on the day before the start of treatment (day 0). After that, all animals underwent laparotomy under isoflurane anaesthesia (isoflurane, Fujifilm Wako Pure Chemical Co., Ltd.), and blood was collected from the abdominal aorta. Of the blood obtained, 2 mL was used for haematological tests, and the rest was used for serum collection. The 2 mL of blood for haematological tests was dispensed into a blood collection tube designated by the laboratory. The blood for serum collection was centrifuged to obtain serum, then frozen. Haematological tests were carried out at Kishimoto Clinical Research Centre, Japan. Using the blood, measurements for blood cell count (RBC), Haematocrit (Ht) and Haemoglobin level (Hb), average red blood cell volume (MCV) was calculated from RBC and Ht. Average erythrocyte haemoglobin (MCH) was calculated from RBC and Hb. Mean erythrocyte haemoglobin concentration (MCHC) was calculated from Ht and Hb platelet count, white blood cell count (WBC), blood image (white blood cell image) by flow cytometry and specular examination using semiconductor laser. The cryopreserved sera were sent to Nagahama Life Science Laboratory, Nagahama Plant, Oriental Yeast Company, Japan, for the following parameters using ELISA: CRP, IL-6, IL-8 IFN and IgA. In addition, NLR was calculated using the actual number of neutrophils and lymphocytes from the WBC fraction obtained from the blood image (leukogram). The number of neutrophils was defined as the total number of rod-shaped nuclei and segmental nuclei. LCR was calculated from the lymphocyte count and CRP. LeCR was calculated from the WBC count and CRP.
Means and standard deviations per group were calculated for body weight on Days 1, 7, 14, 21 and 28; mean daily food intake during the acclimation period; and mean daily food intake on Days 3–6, 10–13, 17–20 and 24–27 of treatment. For haematological tests, NLR, CRP, IgA, IL-6, IL-8, IFN-γ, sFAS and LCR in Groups 2 through 4, the mean values and standard deviations per group were calculated separately for blood samples collected on Day 15 (3 animals) and Day 29 (3 animals). In addition, group means and standard deviations were calculated for haematological tests, NLR, CRP, IgA, IL-6, IL-8, IFN-γ, sFAS, LeCR and LCR in Group 1. The Bartlett test was used to test for equivariance using Excel statistics (Social Information Service Co., Ltd.). Equal variances were analysed using one-way ANOVA, and unequal variances were analysed with the Kruskal-Wallis test. When the one-way ANOVA identified significant differences, Dunnett’s multiple comparison test method was used to compare the mean values with the control group, and test groups. The significance level was set at less than 5%.