Effects of housing conditions on stress, depressive like behavior and sensory-motor performances of C57BL/6 mice.

BACKGROUND: The effects of housing conditions on animal physiology, behavior or stress are still debated. The aim of this study was to investigate the effects of three different housing systems, individually ventilated cages (IVC), classical small cages with floor surface area of 500 cm2 (CC500) and classical large cages with floor surface area of 800 cm2 (CC800) on body weight, sensory-motor performances, depression-like behavior, plasma corticosterone and brain oxidative stress parameters in C57BL/6 mice. The mice housed in one of the cages from birth to 6 months of age. Hang wire and adhesive removal tests were performed to evaluate somatosensory and motor performances. The extent of depression was determined by the forced swim test. Blood corticosterone levels were measured. In addition, brain malondialdehyde (MDA), total antioxidant status (TAS) and total oxidant status (TOS) levels were analyzed. RESULTS: The depression-like behavior of the groups was similar. Although there were no significant differences in hang wire test among groups, CC500 group required longer durations in adhesive removal test. The body weight and plasma corticosterone levels of CC800 group were significantly higher than other groups. The oxidative stress parameters were highest in CC500 cage. CONCLUSIONS: Our study showed that the least stressful housing condition was IVC cage systems. Interestingly, the number of mice in the classical cages had a significant effect on stress levels and sensory-motor performance.

Sensory­motor performance and neurochemical effects in the cerebral cortex of brain­derived neurotrophic factor heterozygous mice fed a high­cholesterol diet.

Reports suggest that a high­cholesterol diet may induce neuroinflammation, oxidative stress, and neurodegeneration in brain tissue. Brain­derived neurotrophic factor (BDNF) might play a role in protecting against changes induced by high cholesterol. We aimed to assess behavioral correlates and biochemical alterations in the motor and sensory cortices following a high­cholesterol diet under normal and reduced BDNF concentrations. C57Bl/6 strain, wild­type (WT) and BDNF heterozygous (+/­) mice were used to reveal the effects of endogenous BDNF concentrations. We compared diet and genotype effects using four experimental groups: WT and BDNF heterozygous (+/­) groups of mice were each fed a normal or high­cholesterol diet for 16 weeks. The cylinder test and wire hanging test were performed to evaluate neuromuscular deficits and cortical sensory­motor functions, respectively. In addition, neuroinflammation was assessed by tumor necrosis factor alpha and interleukin 6 levels measured in the somatosensory and motor areas. Additionally, MDA levels and SOD and CAT activity were evaluated as oxidative stress parameters. Results showed that a high­cholesterol diet significantly impaired behavioral performance in the BDNF (+/­) group. Diet did not change the levels of neuroinflammatory markers in any of the groups. However, MDA levels, an indicator of lipid peroxidation, were significantly higher in the high­cholesterol­fed BDNF (+/­) mice. The results suggest that BDNF levels might be a critical factor in determining the extent of neuronal damage induced in the neocortex by a high­cholesterol diet.

Phoenixin-14 reduces the frequency of interictal-like events in mice brain slices.

Phoenixin-14 (PNX-14) has a wide bioactivity in the central nervous system. Its role in the hypothalamus has been investigated, and it has been reported that it is involved in the regulation of excitability in hypothalamic neurons. However, its role in the regulation of excitability in entorhinal cortex and the hippocampus is unknown. In this study, we investigated whether i. PNX-14 induces any synchronous discharges or epileptiform activity and ii. PNX-14 has any effect on already initiated epileptiform discharges. We used 350 µm thick acute horizontal hippocampal-entorhinal cortex slices obtained from 30- to 35-day-old mice. Extracellular field potential recordings were evaluated in the entorhinal cortex and hippocampus CA1 region. Bath application of PNX-14 did not initiate any epileptiform activity or abnormal discharges. 4-Aminopyridine was applied to induce epileptiform activity in the slices. We found that 200 nM PNX-14 reduced the frequency of interictal-like events in both the entorhinal cortex and hippocampus CA1 region which was induced by 4-aminopyridine. Furthermore, PNX-14 led to a similar suppression in the total power of local field potentials of 1-120 Hz. The frequency or the duration of the ictal events was not affected. These results exhibited for the first time that PNX-14 has a modulatory effect on synchronized neuronal discharges which should be considered in future therapeutic approaches.

The TrkB agonist 7,8-dihydroxyflavone improves sensory-motor performance and reduces lipid peroxidation in old mice.

7,8-Dihydroxyflavone (7,8-DHF) is a natural flavonoid compound that act as Trk-B agonist. 7,8-DHF is also a potent antioxidant. When applied systematically, 7,8-DHF can pass through blood-brain barrier and exhibit potential therapeutic effects in several animal models of neurodegenerative disorders. This study investigates the remedial effects of 7,8-DHF on behavioral impairments and biochemical changes associated with aging with a species emphasis on cortex. For this purpose three experimental groups were formed which are young control group, old group and old-DHF groups. 5 mg/kg 7,8-DHF was administered intraperitoneally to old-DHF group for 3 weeks. We assessed the hang wire and adhesive removal performances of mice. Also, oxidative stress, neuroinflammation and synaptic protein levels in the cortex were measured. We observed that chronic administration of 7,8-DHF improved behavioral performance of old mice. Besides, 7,8-DHF reversed MDA level which was increased in old control animals. However, 3 weeks application of 7,8-DHF failed to recover the levels of neuroinflammation markers (TNF-α and IL-6) and synaptic proteins (PSD-95 and Synaptophysin) which were reduced in old group. These findings demonstrate that improvement of age-dependent behavioral impairments and MDA levels by 7,8-DHF could be attributed to its antioxidant actions.

Pterostilbene administration improves the recovery potential of extremely low-frequency magnetic field in acute renal ischemia-reperfusion injury: an FTIR spectroscopic study.

Renal ischemia-reperfusion (I/R) injury, one of the drastic outcomes of renal failure and organ transplantation, tends to deteriorate over time; therefore, noninvasive therapeutic strategies will avail the progression-free survival of the patients. Magnetic field has been proposed as a noninvasive treatment strategy; however, with recent scientific advances, many controversies have arisen regarding its efficacy. Pterostilbene, a natural analog of resveratrol, was documented to be effective in treatment of I/R injuries. This study aims to assess the acute therapeutic effects of combined extremely low-frequency magnetic field (ELF-MF) and pterostilbene treatment on renal I/R injury. After induction of renal I/R in Wistar rats, treatments of 50 Hz, 1 mT ELF-MF applied alone or in combination with pterostilbene were applied for 5 consecutive days. Kidney homogenates were analyzed by Fourier transform infrared spectroscopy. I/R injury resulted in an altered protein and lipid structure with the dominance of longer acyl chains; a slight decrease in lipid, protein, unsaturated lipid, and unsaturated/saturated lipid content; and an increase in membrane fluidity and lipid peroxidation in rat kidneys. Although ELF-MF treatment alone was not sufficient to restore all ischemia-induced alterations, the combined treatment strategy of pterostilbene administration in the presence of ELF-MF was successful and warrants further investigation.