Concentration-related changes in blood and tissue parameters of hepatotoxicity and their interdependence in rats exposed to bromobenzene and 1,2-dichlorobenzene

Metabolomic changes in severe acute malnutrition suggest hepatic oxidative stress: a secondary analysis

Severe acute malnutrition (SAM), due to poor energy and/or protein intake, is associated with poor growth, depressed immune function, and long-term impacts on metabolic function. As the liver is a major metabolic organ and malnutrition poses metabolic stress, we hypothesize that SAM will be associated with alterations in the hepatic metabolome reflective of oxidative stress, gluconeogenesis, and ketogenesis. Thus, the purpose of this secondary analysis was to understand how SAM alters hepatic metabolism using a piglet model. Weanling piglets were feed either a reference (REF) or protein-energy deficient diet (MAL) for 5 weeks. After dietary treatment MAL piglets were severely underweight (weight-for-age Z-score of -3.29, Welch's t test, P = .0007), moderately wasted (weight-for-length Z-score of-2.49, Welch's t test, P = .003), and tended toward higher hepatic triglyceride content (Welch's t test, P = .07). Hematologic and blood biochemical measurements were assessed at baseline and after dietary treatment. The hepatic metabolome was investigated using ¹H-NMR spectroscopy. Hepatic concentrations of betaine, cysteine, and glutathione tended to be lower in MAL (Welch's t test with FDR correction, P < .1), while inosine, lactate, and methionine sulfoxide concentrations were higher in MAL (inosine: P = .0448, lactate: P = .0258, methionine sulfoxide: P = .0337). These changes suggest that SAM is associated with elevated hepatic oxidative stress, increased gluconeogenesis, and alterations in 1-carbon metabolism.

Indirect and lactation-associated changes in renal alkaline phosphatase of newborn rats prenatally exposed to cadmium chloride

Pregnant Sprague-Dawley rats were intraperitoneally injected with physiological saline solution (vehicle) or cadmium chloride (CdCl2) at 2.5 mg kg-1 body wt. on days 8, 10, 12 and 14 of gestation. Offspring were examined for renal alkaline phosphatase activity (ALP) on postnatal days (PND) 3 and 12, and for kidney metallothionein (MTh) and for liver, kidney and entire gastrointestinal tract 109Cd content at birth and on PND 3 and 12. No effects were observed on neonatal survival or on body, liver and kidney weights of pups up to PND 12. Newborns born and fed by mothers exposed to CdCl2 during pregnancy exhibited a significant decrease in ALP activity on PND 3. Conversely, no significant changes were observed in newborns lactated by surrogate non-treated mothers. Renal MTh increased with age but was not influenced by maternal treatment. Traces of 109Cd were present in the liver at birth (5-7 ng). Thereafter, 109Cd was mainly found in the gastrointestinal tract of newborns lactated by their biological mothers (610-690 ng on PND 12), with a marginal uptake in the liver (10-12 ng on PND 12). 109Cd was not detectable in the kidneys at any age (less than 4 ng). These results show that prenatal exposure to Cd cannot be the sole aetiological agent in the induction of the subtle and transitory changes in renal biochemistry observed in offspring born and fed by female rats intraperitoneally injected with 2.5 mg CdCl2 kg-1 body wt. on days 8, 10, 12 and 14 of gestation. The results also contradict the role of a direct effect on the kidney.

Difference in liver and serum malathion carboxylesterase and glucose-6-phosphatase in detecting carbon tetrachloride-induced liver damage in rats

Microsome, cytosol and serum malathion carboxylesterase (MaCEst) activity was assessed in rats after single i.p. administration of carbon tetrachloride (CCl4) in doses ranging from 0.05 to 1 ml kg-1. MaCEst activities were compared with those of glucose-6-phosphatase (G6-Pase) as an indicator of endoplasmic reticulum damage and serum glutamate dehydrogenase (GLDH) and sorbitol dehydrogenase (SHD) as indicators of liver cytolysis. The data showed a dose-dependent increase in GLDH and SDH serum activities (175% and 68%) from 0.05 ml kg-1; an increase in serum G6-Pase (31%) and a decrease in microsomal G6-Pase (38%) was apparent only after 0.5 or 1.0 ml kg-1 doses. MaCEst activity was unaffected. The results demonstrate that, under these experimental conditions, serum and subcellular measurements of MaCEst activity failed to reveal the liver toxicity of CCl4.

Adrenal-dependent leucopenia after short-term exposure to various airborne irritants in rats

Leucopenia without any change in differential or red blood cell counts was observed in rats exposed for 4 h to increasing concentrations of the following airborne irritants: acetic acid, benzyl chloride, 1,2-dichlorobenzene, ethyl acetate, ethyl acrylate, formaldehyde, isophorone, mesityl oxide, phenol, styrene, toluene diisocyanate and vinyl toluene. This effect was abolished by adrenalectomy. Vinyl toluene and 1,2-dichlorobenzene induced leucopenia at levels as low as their current occupational standards of 50 ppm. With the exception of 1,2-dichlorobenzene, the tested compounds caused leucopenia only when exposure reached the irritant level. It is discussed that stress associated with the irritative effect of chemicals can confound specific haematological effects.

Assessment of the relative hazard involved with airborne irritants with additional hepatotoxic or nephrotoxic properties in mice

This paper deals with the conversion of the hepatotoxicity of 1,2-dichlorobenzene (DCB), the nephrotoxicity of hexachloro-1,3-butadiene (HCBD) and the respiratory effects of these two toxicants into quantal data. It aims to provide some useful information on the best strategy used for safety evaluation. A reflex bradypnea indicative of irritation of the nasal cavities of mice occurred during a 15-min oronasal exposure to each chemical. A reduction in the development of staining for liver glucose-6-phosphatase (G6-phosphatase) and an increase in the number of damaged tubules in cryostat kidney sections stained for alkaline phosphatase were the measure of toxicity in mice subjected to a whole-body 4-h exposure to DCB and HCBD vapours, respectively. The immediate irritant responses, as well as the delayed liver and kidney responses, were measured at the peak of the chemical's action. These maximum responses were then used to establish the relationships of exposure level effects and also the median active levels of exposure (MALs). The DCB and HCBD MALs responsible for a 50% decrease in the respiratory rate of mice (RD50) were 181 and 211 ppm, respectively. The MAL required for eliciting a 50% decrease in G6-phosphatase staining intensity in DCB-exposed mice was 598 ppm and that associated with 50% of damaged tubules in HCBD-exposed mice was 7.2 ppm. On the basis of these quantitative data, potency ratios indicated that irritation and kidney injury are the primary manifestations of toxicity associated with short-term exposure to DCB and HCBD, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)