Francisco A. Posadas del Río

Immediate and delayed effects of lead on AChE, GSH-T and thiols in the substantia nigra, neostriatum and cortex of the rat brain

We studied the effects, at 10 and 30 min, of a single dose (10 mg kg−1) of lead chloride, administered by the intraperitoneal route, on the activities of acetylcholinesterase (AChE) and glutathione transferase (GSH‐T) and on the concentrations of total and non‐protein thiols in substantia nigra compacta (SNCO) and substantia nigra reticulata (SNRE), caudate putamen (CAU) and cerebral cortex (CC) from adult male rats in comparison with the effects of this metal at 24 and 72 h. The main immediate effects of lead consisted of decreased GSH‐T activity and total and non‐protein thiol concentrations in CAU and CC 10 min after administration. These effects were reversed after 30 min but with increased GSH‐T activity in SNCO and AChE activity in SNRE along with diminished concentration of homogenate proteins in SNRE, CAU and CC. The GSH‐T activity again was increased in SNCO but the AChE activity was decreased in CC 24 h after Pb administration; total and non‐protein thiol concentrations were diminished but homogenate protein concentration was augmented in all areas. Finally, 72 h after Pb administration, AChE and GSH‐T activities were decreased in CAU and CC, accompanied by an increased concentration of precipitate and supernatant proteins; supernatant protein concentration also was augmented in SNCO and SNRE; here, again, the concentrations of total and non‐protein thiols were diminished and the homogenate protein concentration was augmented in all areas. Copyright

Identification of leptin gene expression in sinusoidal endothelial rat liver cells.

Sinusoidal endothelial liver cells (SECs) have a key role in the pathophysiology of chronic liver disease. Leptin is an important profibrogenic and proinflammatory cytokine whose expression in sinusoidal endothelial liver has not been documented. The authors studied the potential of rat SECs to express the leptin and leptin receptor genes. Two cell lines of rat SECs were generated from a male rat liver by pronase-collagenase perfusion and dilution cloning. They were characterized according to morphology, ploidy, von Willebrand antigen immunoreactivity, CD31 transcription, matrix metalloproteinase secretion, and pseudocapillary formation. Expression of the leptin and leptin receptor genes was studied using qualitative reverse transcriptase-polymerase chain reaction. Both cell lines fulfilled the accepted criteria for consideration as being derived from the liver sinusoidal endothelium. Confluent monolayers of both cell lines transcribed leptin and leptin receptor genes. This work demonstrated that SECs can transcribe the leptin gene in vitro, cotranscribing with the leptin receptor gene. Leptin production and signaling at this level could be of paramount importance in liver physiopathology; further studies of this issue are warranted because it represents a potential intervention point during chronic liver diseases.

Sex differences in the enzymatic hydrolysis of acetylsalicylic acid by microsomes from various rat tissues

We studied the in vitro hydrolysis of acetylsalicylic acid (ASA) to salicylic acid (SA) catalysed by microsomal preparations from liver, kidney, small intestine and stomach mucosas and blood serum of adult female and male rats. Hepatic microsomes from male rats had the highest specific activity: 42.3 ± 6.0 nmol SA mg−1 min−1 (mean ± SEM). Kidney, intestine, stomach and serum activities were 60, 30, 14 and 0.7% with regard to the liver. In contrast, gastric microsomes from female rats showed the highest specific activity: 53 ± 22.1 nmol SA mg−1 min−1 (mean ± SEM) whereas intestine, liver, kidney and serum activities were 60, 43, 40 and 1.7% with regard to the stomach mucosa. Hepatic, renal and intestinal microsomes had a pH optimum of 5–6. Male rats had Vmax and Km values of 95.5, 83.4 and 29.4 nmol SA mg−1 min−1 and 2.9, 1.27 and 6.4 mM, while for female rats they were 54.8, 75.8 and 59.4 nmol SA mg−1 min−1 and 2.6, 1.35 and 3.4 mM for hepatic, renal and intestinal microsomes, respectively. Parathion inhibited the hydrolysis of ASA with an IC50 of 1.2 × 10−5 M for liver and kidney and 5 × 10−6 M for intestine from male rats.

The Ginkgo biloba Extract Reverses the Renal Effects of Titanium Dioxide Nanoparticles in Adult Male Rats

The Ginkgo biloba extract (GbE) is a commercial product used as a nutraceutic herbal remedy in Europe and US. It contains 27% of the polyphenols isorhamnetin, kaempferol, and quercetin, as antioxidants. We used male adult Wistar rats (200–300 g), divided into four groups: control group (treated with 5.0 mg/kg of sodium chloride, intravenous), titanium dioxide nanoparticles (TiO2-NPs) group (5.0 mg/kg, intravenous), GbE group (10 mg/kg, intraperitoneal), and GbE + TiO2-NPs group (treated 24 h before with 10 mg/kg of GbE, intraperitoneal), followed, 24 h later, by 5.0 mg/kg of TiO2-NPs intravenously. The statistical analysis was performed using Students t-test for grouped data with ANOVA posttest. The GbE protected renal cells against the effects of TiO2-NPs because it reversed the increased activity of γ-glutamyltranspeptidase and the enzymatic activity of dipeptidylaminopeptidase IV at all times tested (0–5, 5–24, 24–48, and 48–72 h). Also it reversed the glucosuria, hypernatriuria, and urine osmolarity at three times tested (5–24, 24–48, and 48–72). Thus, we conclude that GbE has a beneficial activity in the cytoplasmic membranes of brush border cells on the renal tubules, against the adverse effects that can be produced by some xenobiotics in this case the TiO2-NPs, in experimental rats.