Vitamin A depletion alters sensitivity of motor behavior to MK-801 in C57BL/6J mice

Overgrowth of Squamocolumnar Junction and Dysregulation of Stem Cell Lineages in the Stomach of Vitamin A-Deficient Mice

Junctional epithelia are common sites for pathological transformations. In mice, the stratified epithelium of the forestomach joins the simple glandular epithelium of the cardia at the limiting ridge. We previously demonstrated the expression of vitamin A receptors in the gastric stem/progenitor cells and their progeny and found that excess retinoic acid enhances cellular dynamics of gastric epithelium. This study examines how deficiency of vitamin A would alter gastric epithelial stem cell lineages. Three-week-old mice of both genders were weaned and fed with a vitamin A deficient (VAD) diet for 4 or 8 months. Sex- and weight-matched littermate mice received a standard (control) diet. To label S-phase cells, all mice received a single intraperitoneal injection of 5-bromo-2-deoxyuridine before being euthanized. Stomach tissues were processed for microscopic examination and protein analysis to investigate stem cell lineages using different stains, lectins, or antibodies. The Student’s t-test was used to compare quantified data showing differences between control and VAD groups. Eight-month-vitamin-A deficiency caused enlarged forestomach and overgrowth of the squamocolumnar junction with metaplastic and dysplastic cardiac glands, formation of intramucosal cysts, loss of surface mucosal integrity, increased amount of luminal surface mucus, and upregulation of trefoil factor 1 and H⁺,K⁺-ATPase. These changes were associated with decreased cell proliferation and upregulation of p63. In conclusion, vitamin A is necessary for maintaining gastric epithelial integrity and its deficiency predisposes the mouse stomach to precancerous lesions.

Current Evidence for Developmental, Structural, and Functional Brain Defects following Prenatal Radiation Exposure

Ionizing radiation is omnipresent. We are continuously exposed to natural (e.g., radon and cosmic) and man-made radiation sources, including those from industry but especially from the medical sector. The increasing use of medical radiation modalities, in particular those employing low-dose radiation such as CT scans, raises concerns regarding the effects of cumulative exposure doses and the inappropriate utilization of these imaging techniques. One of the major goals in the radioprotection field is to better understand the potential health risk posed to the unborn child after radiation exposure to the pregnant mother, of which the first convincing evidence came from epidemiological studies on in utero exposed atomic bomb survivors. In the following years, animal models have proven to be an essential tool to further characterize brain developmental defects and consequent functional deficits. However, the identification of a possible dose threshold is far from complete and a sound link between early defects and persistent anomalies has not yet been established. This review provides an overview of the current knowledge on brain developmental and persistent defects resulting from in utero radiation exposure and addresses the many questions that still remain to be answered.

Vitamin A deficiency induces structural and functional alterations in the molecular constituents of the rat hippocampus

To date, no structural study has been carried out on the effects of vitamin A deficiency (VAD) on hippocampal macromolecules. Therefore, in the present study, the effect of dietary VAD on the structure, content and function of rat hippocampal molecules was investigated using Fourier transform IF spectroscopy. Male Wistar rats were randomly divided into three groups: an experimental group maintained on a vitamin A-deficient liquid diet (VAD,n7); a control group maintained on a vitamin A-supplemented liquid diet (CON,n9); a pure control group maintained on standard solid laboratory chow (PC,n7). The PC group was included in the study to ensure that the usage of liquid diet did not influence the outcomes of VAD. Both the CON and PC groups were successfully discriminated from the VAD group by principal component analysis and hierarchical cluster analysis. The spectral analysis indicated a significant decrease in the contents of saturated and unsaturated lipids, cholesteryl esters, TAG and nucleic acids in the VAD group when compared with the CON group (P≤ 0·05). In addition, a significant decrease in membrane fluidity and a significant increase in lipid order (e.g. acyl chain flexibility) were observed in the VAD group (P≤ 0·001). The results of the artificial neural network analysis revealed a significant decrease in the α-helix structure content and a significant increase in the turn and random coil structure contents, indicating protein denaturation, in the VAD group when compared with the CON and PC groups (P≤ 0·05). Dietary exclusion of vitamin A for 3 months apparently had an adverse impact on compositional, structural and dynamical parameters. These changes can be due to increased oxidative stress, confirming the antioxidant protection provided by vitamin A when used as a dietary supplement at low-to-moderate doses.

The effect of 4-week training period on plasma neuropeptide Y, leptin and ghrelin responses in male rowers

The aim was to investigate the effect of high-volume low intensity resistance training protocol combined with endurance training on plasma neuropeptide Y (NPY) concentration in rowers. Additionally, leptin and ghrelin, as markers for body energy balance concentrations, were monitored. 12 highly trained national and international level male rowers participated in this study. The participants were tested three times--after reference week (T1), after 2 weeks of high-volume training (T2) and after a recovery week (T3) for aerobic performance, energy intake and expenditure, and blood biochemical parameters. The submaximal rowing performance decreased significantly (P = 0.019) at T2. Fasting leptin decreased significantly (from 2.05 ± 0.88 to 1.28 ± 0.53 ng/mL; P = 0.009) at T2 and increased significantly (from 1.28 ± 0.53 to 1.79 ± 0.79 ng/mL; P = 0.002) at T3. Fasting ghrelin decreased significantly (from 980 ± 300.2 to 873.35 ± 198.6 pg/mL; P = 0.036) at T3 compared to T2, while no changes were found in fasting NPY. Significant decreases in exercise-induced leptin were observed at T2 (from 1.13 ± 0.5 to 1.08 ± 0.5 ng/mL; P = 0.012), PRE and POST test leptin values at T2 were significantly decreased compared to T1(1.40 ± 0.9 to 1.13 ± 0.5 and 1.44 ± 0.8 to 1.08 ± 0.5, respectively). Acute exercise-induced increases in NPY were found at T2 (from 128.1 ± 23.2 to 155.1 ± 28.9 pmol/L; P = 0.002) and at T3 (from 131.3 ± 20.5 to 159.7 ± 32.8 pmol/L, P = 0.004). In conclusion, the combination of high-volume training protocol and energy imbalance induces significant post-exercise changes in NPY, leptin, and ghrelin concentrations and decreases fasting leptin.