Which precocial rodent species is more suitable as the experimental model of microgravity influence on prenatal musculosketal development on international space station?

The International Space Station (ISS) has the possibility to perform experiments regarding rodent reproduction in microgravity. The musculoskeletal system at birth in precocial rodent species more resembles the human than that of altricial rodent species. For precocial rodent species with body weight ≤ 500 g (limit of ISS) determined were: adult body mass, newborn body mass, head-body length, tail length, existing variants (wild, domesticated, laboratory), single/group housing, dry food consumption/24 h, water intake/24 h, basal metabolic rate mlO2/g/h, environmental temperature, sand baths, urine output ml/24 h, fecal output g/24 h, size of fecal droplet, hair length, life span, length of oestrus cycle, duration of pregnancy, building nest, litter size, stage of musculoskeletal maturity at birth, and the duration of weaning. Characteristics were obtained by searching SCOPUS as well as the World Wide Web with key words for each of the species in English, Latin and, local language name. These characteristics were compared in order to find most appropriate species. Twelve precocial rodent species were identified. There is not enough data for Common yellow-toothed cavy, and Eastern spiny mouse. Inappropriate species were: Gundis, Dassie rat are a more demanding species for appropriate tending, litter size is small; Octodon degus requires sand baths as well as a nest during the first two weeks after delivery; muscle maturity of Spiny mouse at birth (myotubular stage), does not correspond to the human (late histochemical stage); Chinchilla requires separately housing, daily sand baths, has upper limit of weight. Possibility of keeping Southern mountain cavy as pet animal, short estrus, large litter size, absence of the need for nest and sand baths, makes this species the most promising candidates for experiments on ISS. If an experiment is planned with exposing gravid animals before term of the birth, then they might be kept together in the existing Rodent Habitat (USA). If an experiment with birth in microgravity is planned on ISS, the existing habitats do not provide conditions for such an experiment. It is necessary to develop habitats for separate keeping of pregnant animals to enable the following: 1. undisturbed delivery 2. prevent the possibility of hurting the newborns 3. ensure adequate post-partum maternal care and nursing.

An Extremely Low Frequency Magnetic Field and Global Cerebral Ischemia Affect Pituitary ACTH and TSH Cells in Gerbils.

The neuroendocrine system can be modulated by a magnetic field and cerebral ischemia as external and internal stressors, respectively. This study deals with the separate or combined effects of an extremely low frequency (ELF) magnetic field (50 Hz, average magnetic field of 0.5 mT) for 7 days and global cerebral ischemia for 10 min on the morpho-functional features of pituitary adrenocorticotrophic (ACTH) and thyrotrophic (TSH) cells in 3-month-old gerbils. To determine the immediate and delayed effects of the applied stressors, measurements were made on the 7th and 14th days after the onset of the experiment. The ELF magnetic field and 10-min global cerebral ischemia, separately and particularly in combination, decreased (P < 0.05) the volume density of ACTH cells, while only in combination were intracellular ACTH content and plasma ACTH concentration increased (P < 0.05) on day 7. The ELF magnetic field elevated serum TSH concentration on day 7 and intracellular TSHß content on day 14 (P < 0.05). Also, 10-min global cerebral ischemia alone increased serum TSH concentration (P < 0.05), while in combination with the ELF magnetic field it elevated (P < 0.05) intracellular TSHß content on day 14. In conclusion, an ELF magnetic field and/or 10-min global cerebral ischemia can induce immediate and delayed stimulation of ACTH and TSH synthesis and secretion. Bioelectromagnetics. 2020;41:91-103. © 2019 Bioelectromagnetics Society.

Cadmium and high temperature effects on brain and behaviour of Lymantria dispar L. caterpillars originating from polluted and less-polluted forests.

Insects brain as a part of nervous system is the first-line of fast stress response that integrate stress signals to regulate all aspects of insect physiology and behaviour. The cadmium (Cd) bioaccumulation factor (BF), activity of the neurotoxicity biomarker acetylcholinesterase (AChE), dopamine content, expression and amount of Hsp70 in the brain and locomotor activity were evaluated in the 4th instar of Lymantria dispar L. caterpillars fed a Cd supplemented diet and reared in an optimal temperature regime (23 °C) and/or exposed to high temperature (28 °C). The insects originated from two forests, one close to "Nikola Tesla" thermoelectric power plant, Obrenovac (polluted population), and the other Kosmaj mountain (less-polluted population, far from any industrial region). The Cd BF was higher in the less-polluted than in the polluted population especially at the high ambient temperature. AChE activity and dopamine content were changed in the brains of L. dispar from both populations in the same manner. Hsp70 concentration in caterpillar brains showed opposite trends, a decrease in the less-polluted and an increase in the polluted population. Locomotor activity was modified in both Lymantria dispar populations, but the pattern of changes depended on the stressors and their combined effect. ACh activity and dopamine content are sensitive parameters to Cd exposure, regardless of pollutant experience, and might be promising biomarkers in monitoring forest ecosystems.