Advance in Tissue Differentiation and its Regulatory Mechanisms by Master Proteins of Nervous System during Weaning.

Weaning is a critical period for the growth and development of mammals, in which various physiological and biochemical indicators of the body have undergone great changes. The development, differentiation, and maturation of the nervous system are regulated by many proteins. Changes in related proteins affect the physiological functions of the nervous system. However, the regulation of selfrenewal and differentiation of the nervous system at this stage is still poorly understood. The mechanism of differentiation and regulation of the major proteins in the nervous system during this special period of weaning remains to be investigated. Therefore, this paper aims to summarize the alteration of the nervous system during weaning and provide the basis for subsequent research.

Systems toxicology used in nanotoxicology: mechanistic insights into the hepatotoxicity of nano-copper particles from toxicogenomics.

In some studies, nano-copper particles have been found to be acutely toxic to exposed mice, with the liver and kidney being the target tissues. However, the characteristics of subacute toxicity from repeated nano-copper exposure in rats and the molecular mechanism of its hepatotoxicity at the genomic level remain unclear. We investigated the mechanisms of nano-copper-induced hepatotoxicity, which were identified from hepatic gene expression profiles that were phenotypically anchored to conventional toxicological outcomes, and identified biomarkers of nanotoxicity caused by nano-copper. Male Wistar rats were administered nano-copper or micro-copper at different doses for five days. Subsequently, we examined conventional toxicological parameters including body weight, clinical chemistry, and histopathology, and also used microarrays to identify gene expression changes in rat liver. High dose nano-copper induced increases in alanine aminotransferase, aspartate aminotransferase, triglyceride, total bilirubin, total bile acid levels, and a decrease in body weight. Histopathological studies of the liver indicated scattered, dotted hepatocytic necrosis in all rats in the high dose nano-copper group. Identified genes from the group receiving the high dose were functionally categorized, and results showed that genes related to oxidoreductase activity, metabolism, and signal transduction were involved in the development of the observed phenotypes. The results also suggest that altered gene expression patterns induced by exposure to a low, subtoxic dose of nano-copper may reveal signs of cell stress or subtle cell injury indicative of overt toxicity at higher doses. Results in this study provide new insights into the toxicology of nano-copper particles and illustrate how toxicogenomic approaches are providing an unprecedented amount of mechanistic information on molecular responses to nano-copper, as well as how they are likely to impact hazard and risk assessment. Gene expression changes are likely to be more sensitive indicators of potential adverse effects than traditional measurements of toxicity.

Plasma and liver proteomic analysis of 3Z-3-[(1H-pyrrol-2-yl)-methylidene]-1-(1-piperidinylmethyl)-1,3-2H-indol-2-one-induced hepatotoxicity in Wistar rats.

3Z-3-[(1H-pyrrol-2-yl)-methylidene]-1-(1-piperidinylmethyl)-1,3-2H-indol-2-one (Z24), a synthetic anti-angiogenic compound, inhibits the growth and metastasis of certain tumors. Previous works have shown that Z24 induces hepatotoxicity in rodents. We examined the hepatotoxic mechanism of Z24 at the protein level and looked for potential biomarkers. We used 2-DE and MALDI-TOF/TOF MS to analyze alternatively expressed proteins in rat liver and plasma after Z24 administration. We also examined apoptosis in rat liver and measured levels of intramitochondrial ROS and NAD(P)H redox in liver cells. We found that 22 nonredundant proteins in the liver and 11 in the plasma were differentially expressed. These proteins were involved in several important metabolic pathways, including carbohydrate, lipid, amino acid, and energy metabolism, biotransformation, apoptosis, etc. Apoptosis in rat liver was confirmed with the terminal deoxynucleotidyl transferase dUTP-nick end labeling assay. In mitochondria, Z24 increased the ROS and decreased the NAD(P)H levels. Thus, inhibition of carbohydrate aerobic oxidation, fatty acid beta-oxidation, and oxidative phosphorylation is a potential mechanism of Z24-induced hepatotoxicity, resulting in mitochondrial dysfunction and apoptosis-mediated cell death. In addition, fetub protein and argininosuccinate synthase in plasma may be potential biomarkers of Z24-induced hepatotoxicity.

Immunocytochemical analysis of syntaxin-1 in rat circumvallate taste buds.

Mammalian buds contain a variety of morphological taste cell types, but the type III taste cell is the only cell type that has synapses onto nerve processes. We hypothesize that taste cell synapses utilize the SNARE protein machinery syntaxin, SNAP-25, and synaptobrevin, as is used by synapses in the central nervous system (CNS) for Ca2+-dependent exocytosis. Previous studies have shown that taste cells with synapses display SNAP-25- and synaptobrevin-2-like immunoreactivity (LIR) (Yang et al. [2000a] J Comp Neurol 424:205-215, [2004] J Comp Neurol 471:59-71). In the present study we investigated the presynaptic membrane protein, syntaxin-1, in circumvallate taste buds of the rat. Our results indicate that diffuse cytoplasmic and punctate syntaxin-1-LIR are present in different subsets of taste cells. Diffuse, cytoplasmic syntaxin-1-LIR is present in type III cells while punctate syntaxin-1-LIR is present in type II cells. The punctate syntaxin-1-LIR is believed to be associated with Golgi bodies. All of the synapses associated with syntaxin-1-LIR taste cells are from type III cells onto nerve processes. These results support the proposition that taste cell synapses use classical SNARE machinery such as syntaxin-1 for neurotransmitter release in rat circumvallate taste buds.

Qualitative and quantitative differences between taste buds of the rat and mouse.

BACKGROUND: Numerous electrophysiological, ultrastructural, and immunocytochemical studies on rodent taste buds have been carried out on rat taste buds. In recent years, however, the mouse has become the species of choice for molecular and other studies on sensory transduction in taste buds. Do rat and mouse taste buds have the same cell types, sensory transduction markers and synaptic proteins? In the present study we have used antisera directed against PLCbeta2, alpha-gustducin, serotonin (5-HT), PGP 9.5 and synaptobrevin-2 to determine the percentages of taste cells expressing these markers in taste buds in both rodent species. We also determined the numbers of taste cells in the taste buds as well as taste bud volume. RESULTS: There are significant differences (p < 0.05) between mouse and rat taste buds in the percentages of taste cells displaying immunoreactivity for all five markers. Rat taste buds display significantly more immunoreactivity than mice for PLCbeta2 (31.8% vs 19.6%), alpha-gustducin (18% vs 14.6%), and synaptobrevin-2 (31.2% vs 26.3%). Mice, however, have more cells that display immunoreactivity to 5-HT (15.9% vs 13.7%) and PGP 9.5 (14.3% vs 9.4%). Mouse taste buds contain an average of 85.8 taste cells vs 68.4 taste cells in rat taste buds. The average volume of a mouse taste bud (42,000 microm3) is smaller than a rat taste bud (64,200 microm3). The numerical density of taste cells in mouse circumvallate taste buds (2.1 cells/1000 microm3) is significantly higher than that in the rat (1.2 cells/1000 microm3). CONCLUSION: These results suggest that rats and mice differ significantly in the percentages of taste cells expressing signaling molecules. We speculate that these observed dissimilarities may reflect differences in their gustatory processing.