Fundamental Toxicological Sciences

2023 - Vol. 10 No. 5

2023 - Vol. 10

Original Article
Effect of Anakinra (Kineret®) treatment on acrylamide-induced neurotoxicity in mice Vol.10, No.5, p.221-231
Alzahraa Fergany , Frederick Adams Ekuban , Cai Zong , Gaku Ichihara
Released: October 06, 2023
Abstract Full Text PDF[2M]

Recent studies demonstrated that upregulation of proinflammatory cytokines were associated with neurotoxicity of acrylamide, which is used widely in industries and generated in food cooked at high temperature. The interleukin-1 (IL-1) is one of cytokines that play an important role in immune response. Anakinra is an IL-1 receptor antagonist used as anti-inflammatory medicine against inflammatory diseases such as juvenile idiopathic arthritis. In this study, ten-week old wild type male mice were allocated into 6 groups. Group 1 to 3 daily received subcutaneous injection with vehicle and oral exposure to ACR in drinking water at 0, 150 or 300 ppm for 28 days, and group 4-6 daily received injection with Anakinra and oral exposure to ACR in drinking water at 0, 150 or 300 ppm for 28 days. The landing foot spread (LFS) test was carried out to assess the motor function, and immunohistochemistry was carried out for quantification of noradrenergic axons and microglia activation. The results of LFS did not show significant effect of Anakinra treatment on ACR-induced increase in landing foot spread in mice. The body weight was dose-dependently decreased by ACR exposure only in the groups treated with Anakinra. The IHC staining for microglia and noradrenergic axon density does not show any significant effect of treatment with Anakinra or exposure to ACR. The study demonstrated that daily treatment with Anakinra at 25 mg/kg body weight does not ameliorate ACR-induced neurotoxicity in mice, while potentiates ACR-induced loss of body weight.

Original Article
Subchronic oral toxicity study of Monascus Color in beagle dogs Vol.10, No.5, p.209-219
Akihiro Hagiwara , Yunagi Murase , Shuuhei Kubo , Haruko Koizumi , Mikio Nakamura , Shoji Fukushima
Released: September 25, 2023
Abstract Full Text PDF[836K]

Monascus Color Y-001, a natural food pigment produced from Monascus purpureus Y-001 fermentation, was administered orally by gavage to 4 Beagle dogs/sex/group for 90 days at doses of 0 (vehicle: 0.1% Tween 80, 10 mL/kg bw), 1, 5 and 25 mg/kg bw/day. In the clinical observations, vomiting/vomitus (dark red watery substance or undigested feed) was observed for males and females in the 25, but not 5 or 1 mg/kg bw/day group at a relatively high frequency. In addition, loose stools were observed for males in this group on a single occasion. These signs were considered to be effects of the test article on the digestive tract. No treatment-related effects were noted in the detailed observations for symptoms, body weights, food consumptions, ophthalmology, hematology, clinical chemistry, urinalysis, gross pathology, organ weights or histopathology. Thus, the no-observed-adverse-effect level (NOAEL) was judged to be 5 mg/kg bw/day in both sexes of the dogs.

Original Article
Investigation of the maximum feasible volume of subretinal injections into rat and cynomolgus monkey eyes Vol.10, No.5, p.199-208
Megumi Sakata , Tomoaki Araki , Masayuki Tomohiro
Released: August 10, 2023
Abstract Full Text PDF[3M]

Subretinal injection is widely used in gene therapy research on age-related macular degeneration and retinitis pigmentosa. We investigated a method of injection and the maximum feasible volume for subretinal injections in rats and monkeys to support future studies for evaluation of new therapies in these animals. Physiological saline was injected subretinally into the eyes of male adult rats (n = 3 eyes/group) and cynomolgus monkeys (n = 3 eyes/group). The eyes were then examined by ophthalmoscopy (slit lamp and ocular fundus examinations), optical coherence tomography (OCT), intraocular pressure (IOP) measurements, or electroretinography (ERG). Rats received physiological saline at 1, 2, 5 µL/eye (2 sec/eye, bolus) and 5 µL/eye (5 µL/min). Monkeys received physiological saline at 50, 100, 150, 200, and 250 µL/eye (10 µL/sec). In all rats and cynomolgus monkeys, successful injection was visually confirmed by bleb formation using OCT at the appropriate sites immediately after injection. IOP increased more than 2-fold after injection of 5 µL/eye (5 µL/2 sec) compared with before injection but remained virtually unchanged at other volumes. Monkeys that received 200 or 250 µL/eye showed a marked increase in IOP immediately after injection, with functional abnormality observed in ERG. In conclusion, bleb formation at the appropriate sites was confirmed by OCT, demonstrating successful subretinal injections to rat and monkey eyes. When physiological saline solution is subretinally injected, the maximum feasible volume is considered to be 5 µL/eye (5 µL/min) in rats and 150 µL/eye (10 µL/sec) in cynomolgus monkeys, based on IOP and ERG results.

Original Article
An application of the magnetometer detection system to Crl:CD1 (ICR) mice for head twitch response induced by hallucinogenic 5-HT2A agonists Vol.10, No.5, p.189-197
Mari Nakamura , Motoki Hojo , Ayaka Kawai , Kiyomi Ikushima , Akemichi Nagasawa , Hideyo Takahashi , Kosho Makino , Toshinari Suzuki , Jin Suzuki , Akiko Inomata
Released: August 10, 2023
Abstract Full Text PDF[4M]

The head twitch response (HTR), a rapid reciprocal head movement, is a reliable behavioral indicator in rodents following the administration of hallucinogens. It is considered a model for predicting psychedelic activity in humans. A recently developed magnetometer system, consisting of a head-mounted magnet and a magnetometer coil, offers a promising alternative to laborious manual counting of HTR in animal experiments; however, it requires relatively complex analytical processes. In this study, our aim was to explore a simple and practical application of this system in ICR mice. Mice implanted with magnets were administered lysergic acid diethylamide (LSD) or (±)-2,5-dimethoxy-4-iodoamphetamine (DOI), and their HTRs were recorded using the magnetometer system. The outputted wave signals were subjected to a 2-step screening: cutoffs for frequency band and amplitude, and manual sorting of the resulting waves. Validation through video scoring revealed a high detection accuracy of the magnetometer system, reaching nearly 99%. Next, we conducted detailed dose-response analyses for the two psychedelics at a dose range of 0.01–3 mg/kg (LSD) or 0.1–25 mg/kg (DOI). The dose-response curves displayed typical inverted U-shaped patterns, and the ED50 value was calculated as 0.086 mg/kg for LSD and 1.42 mg/kg for DOI. Lastly, we explored a simpler screening method using a relatively strict set of filtering criteria instead of the 2-step screening process. A series of validation tests demonstrated that this method can detect HTR with a mean error rate of 11.20%. Our findings provide an option for the application of the magnetometer system and offer fundamental information about experimental conditions suitable for conducting HTR tests in ICR mice.

Effect of blood collection tubes containing separation gels on the measurement of drug concentrations in clinical toxicology Vol.10, No.5, p.179-187
Mayuu Tokudome , Asuka Kaizaki-Mitsumoto , Satoshi Numazawa
Released: August 04, 2023
Abstract Full Text PDF[1M]

Serum separation gels are problematic in therapeutic drug monitoring because they adsorb some of the target drugs; however, the adsorptive properties of drugs that cause clinical intoxication remain unelucidated. Drug adsorption to separators results in a decrease in the observed blood levels, which may lead to uncertain assessments of clinical toxicology. Therefore, this study aimed to clarify the effects of four brands of blood collection tubes with serum separation gels that are used in Japan on the blood concentrations of central nervous system-acting drugs. Amitriptyline-, amoxapine-, mirtazapine-, chlorpromazine-, and flunitrazepam-spiked plasma at respective intoxicated concentrations were incubated in blood collecting tubes with serum separators, namely Vacutainer, Neotube, Insepack, and Venoject, at 4°C or 25°C for up to 72 or 168 hr and compared with control tubes without a serum separator. The amitriptyline, chlorpromazine, and flunitrazepam concentrations significantly decreased, even in control tubes. All the tubes containing serum separators significantly reduced the observed drug concentration when incubated at 25°C, which was estimated using a power function. Except amoxapine, rest all drugs when incubated at 4°C showed a decrease in concentration, albeit to a lesser degree than at 25°C. The blood collection tube with the greatest decrease in concentration was the Vacutainer. In conclusion, although the possibility of drug degradation in plasma must be considered, control tubes are strongly recommended for clinical toxicology, in addition to therapeutic drug monitoring, because drug adsorption is less likely to occur in these tubes.