We have recently started using Wistar Hannover rats in Japan and are now collecting background data. We have been frequently observing corneal mineralization in Wistar Hannover rats of both the RccHanTM:WIST and Crl:WI (Han) strains. In this study, details of corneal mineralization in Wistar Hannover rats were histopathologically and ultrastructurally investigated. According to the results, Wistar Hannover rats had a much higher incidence of corneal mineralization compared with Sprague-Dawley rats. The incidence of corneal mineralization was higher in males than females. According to the histological examination, mineral deposits were positive for calcium by von Kossa’s method. Furthermore, in response to mineralization, keratocytes probably become active to play an important role against the mineralized substance.

To investigate the effects of environmental enrichment on laboratory monkeys, we studied behavioral and physiological differences following changes in housing conditions. Ten male and female juvenile cynomolgus monkeys were first housed in pairs for 8 weeks after quarantine/acclimatization (singly housed) and subsequently housed alone for the next 8 weeks. Monkeys were subjected to evaluations of body weight gain, stereotypic or affiliative behaviors, cortisol, 4-ethylphenyl sulfate (4EPS) and catecholamine concentrations in biological samples, and blood chemistry tests under both housing conditions. Under paired housing, the stereotypic behavioral score decreased in both sexes, and the affiliative behavioral score increased in males and showed an increasing trend in females. Under single housing, the stereotypic score increased in both sexes, and the affiliative score decreased in males. Paired housing decreased serum calcium and urine cortisol concentrations in both sexes and decreased plasma cortisol in males and plasma 4EPS concentrations in females. The stereotypic score was positively correlated with serum calcium, plasma and urine cortisol, and plasma 4EPS concentration and negatively correlated with the affiliative score. The feces painting score, affiliative score, and plasma cortisol and serum calcium concentrations showed sex differences, suggesting differences in responsiveness to environmental changes between males and females. In conclusion, paired housing improved behavioral abnormalities in juvenile cynomolgus monkeys, suggesting that it may be an effective environmental enrichment paradigm. Calcium, cortisol, and 4EPS concentrations in biological samples may be useful indices for evaluating the effects of environmental enrichment.

To evaluate the sedative and physiological effects of alfaxalone intramuscular (IM) administration, 12 healthy cynomolgus monkeys were administered single IM doses of alfaxalone at 0.625 mg/kg (ALFX0.625), 1.25 mg/kg (ALFX1.25), 2.5 mg/kg (ALFX2.5), 5 mg/kg (ALFX5), 7.5 mg/kg (ALFX7.5), or 10 mg/kg (ALFX10); saline was used as the control (CONT). The sedative effects were subjectively evaluated using a composite measure scoring system in six animals. Changes in respiratory rate, pulse rate, non-invasive blood pressure, percutaneous oxygen-hemoglobin saturation (SpO 2 ), and rectal temperature were observed after IM treatments in the other six animals. All animals were allowed to lay down following the ALFX5, ALFX7.5, and ALFX10 treatments, whereas lateral recumbency was achieved in only two animals after ALFX2.5 treatment and none after the CONT, ALFX 0.625, and ALFX1.25 treatments. The median time (interquartile range) to lateral recumbency was 6.5 min (5.3–7.8), 4.0 min (4.0–4.0), and 3.0 min (3.0–3.8), and the duration of immobilization was 27.5 min (19.0–33.8), 56.0 min (42.3–60.8), and 74.5 min (62.8–78.0) after the ALFX5, ALFX7.5, and ALFX10 treatments, respectively. Endotracheal intubation was achieved in all six animals after the ALFX7.5 and ALFX10 treatments. Dose-dependent decreases in respiratory rate, non-invasive blood pressure, SpO 2 , and rectal temperature were observed, and the quality of recovery was smooth in all animals after the ALFX5, ALFX7.5, and ALFX10 treatments. Thus, alfaxalone IM induced a dose-dependent sedative effect in cynomolgus monkeys, but at higher doses, hypotension, hypoxemia, and hypothermia could be induced.