CD-1 mice females recognize male reproductive success via volatile organic compounds in urine.

Sexual selection is considered as one of the leading factors of evolutionary development. In the conditions of incessant competition, specialized methods of attracting individuals of the opposite sex as well as criteria for assessing the quality of a sexual partner have been formed. In order for animals to rely on signaling from sexual partners, the signal must reflect the morpho-physiological status of animals. A high reproductive efficiency of male mice is a good advantage for mate selection and thus must be somehow demonstrated to potential mates. The aim of our study was to find out if male mice could demonstrate their reproductive efficiency through urine volatile organic compounds. The experiment implies cohabiting one male with two mature females for 6 days. The reproductive success of the male was assessed by the presence or absence of pregnant females. At the same time, naive females, who did not participate in reproduction, assessed the urine of the successful males as more attractive, which was expressed in shorter Latency time of sniffs in the Olfactory test. Using a rapid headspace GC/MS analysis, we have found volatile organic compounds (VOCs) in male urine that correlated with female behavior. It turned out that these substances are derivatives of mouse pheromone 6-hydroxy-6-methyl-3-heptanone. The amplitude of peaks corresponding to this pheromone correlated with the testosterone level in blood and the weight of preputial glands. The amplitude of peaks increased in males after mating with whom the females turned out to be pregnant. It is important to note that body weight, weight of testes, weight of seminal vesicles, weight of preputial glands, and plasma testosterone level alone are not reliable indicators of male reproductive success. Thus, the content of the pheromone 6-hydroxy-6-methyl-3-heptanone in the urine of males can serve as a good predictor of the quality of the male as a sexual partner for female CD-1 mice.

Erratum to: "Anxiety and neurometabolite levels in the hippocampus and amygdala after prolonged exposure to predator-scent stress".

Vavilovskii Zhurnal Genetiki i Selektsii = Vavilov Journal of Genetics and Breeding. 2019;23(5):582-587 (in Russian) Page 587, in Acknowledgements instead of The animals and behavioral testing are supported by the budget project (No. 0324-2019-0041). The MRI study is supported by the budget project (No. 0259-2019-0004). All studies are implemented using the equipment of Center for Genetic Resources of Laboratory Animals at ICG SB RAS, supported by the Ministry of Education and Science of Russia (Unique ID# of the project: RFMEFI62117X0015). should read The animals and behavioral testing are supported by the budget project (No. 0324-2019-0041). The MRI study is supported by the budget project (No. 0259-2019-0004). All studies are implemented using the equipment of Center for Genetic Resources of Laboratory Animals at ICG SB RAS, supported by the Ministry of Education and Science of Russia (Unique ID# of the project: RFMEFI62117X0015). The study was conducted within the basic part of the state task of the Ministry of Science and Higher Education of the Russian Federation (No. 17.7255.2017/8.9). The original article can be found under DOI 10.18699/VJ19.528.

Effects of Melatonin on the Body Composition, Physical Performance, and Blood Erythrocyte Indexes of C57Bl/6J Mice Exposed to Continuous Illumination.

Male C57Bl/6J mice were exposed to daily 24-h illumination over 14 days and daily intragastrically received melatonin (1 mg/kg) or water (placebo). Controls were kept under standard day/night (14/10 h) conditions. Melatonin prevented the development of anemia in mice exposed to continuous illumination, which was proven by higher blood hemoglobin levels by the end of the experiment in melatonin-treated animals in comparison with the placebo group. Studies by the low-field NMR spectrometry detected lower lean body mass, total body water, and especially, fat content (by ~13%) in animals receiving placebo. Melatonin treatment led to an increase in the lean body mass and total body water on day 7 (in comparison with the placebo group) without affecting fat mass. On day 14 of continuous illumination, lean body mass increased in comparison with the corresponding parameter in the control and placebo groups. Melatonin had no effect on the physical endurance of mice exposed to continuous illumination (assessed by the grid hanging test).

Relationships between Body Composition and Plasma Levels of Pancreatic, Gut, and Adipose Tissue Hormones in db/db Mice, a Model of Type 2 Diabetes Mellitus.

We studied the relationships between body composition parameters and plasma levels of pancreatic, gut, and adipose tissue hormones regulating energy balance and glucose metabolism in diabetic db/db mice (BKS.Cg-Dock7m+/+Leprdb/J). The body composition parameters in mice aged 8, 12, and 16 weeks were assessed by magnetic resonance imaging. The concentrations of insulin, glucagon, ghrelin, glucagon-like peptide-1, glucose-dependent immunotropic peptide, leptin, resistin, and plasminogen activator-1 were measured by multiplex analysis at the age of 8 and 16 weeks. In comparison with non-diabetic control (db/+), db/db mice demonstrated high fat mass and reduced lean body mass and water content. In 8- and 16-week-old db/db mice, the levels of leptin (p<0.001), insulin (p<0.01), and glucagon-like peptide-1 (p<0.05) were elevated and the concentration of ghrelin (p<0.05) was reduced. The body weight and fat mass positively correlated with the levels of leptin, insulin, plasminogen activator-1, and glucagon-like peptide-1 and negatively correlated with ghrelin concentration. The results provide further details for characteristics of db/db mice, a widely used model of obesity and type 2 diabetes mellitus.