Studies on the toxicity of hexachlorophene in the rat

Hexachlorophene and cuprizone induce the spongy change of the developing rat brain by different mechanisms: the role of 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNPase)

The goal of this research was to identify mechanisms responsible for the spongy change induced in rats after repeated hexachlorophene (HCP) or cuprizone (CPZ) dosing. Rats were dosed with 35 mg/kg HCP for 5 days followed by drug withdrawal for 7 days suffered spongy changes to the white matter of the cerebrum, cerebellum, medulla oblongata, and spinal cord that were accompanied by degeneration of oligodendroglia. The severity of both lesions increased prominently on day 5; however, the spongy change decreased and degeneration of oligodendroglia reversed on day 12 (7 days after dosing ceased). On day 12, cerebral cortex oligodendroglia were stained strongly by anti-CNPase. Other rats were fed for 8 days with powdered chow containing 1% (w/w) CPZ, which was then withdrawn for 16 days. The rats exhibited the spongy change in the white matter of the cerebrum and cerebellum as well as oligodendroglial cell death from day 3. The severity of both lesions increased prominently on day 8. Cerebral cortex oligodendroglia were stained strongly by anti-CNPase on days 3 to 8 and decreased to the control levels by day 24 (16 days after dosing ceased). Electron microscopy revealed that oligodendroglia frequently displayed apoptotic morphology. These findings suggest that CNPase expression was induced in the course of restoration following HCP-induced insults to oligodendroglia and the myelin sheath, and in the course of demyelination by CPZ-induced damage to oligodendroglia. However, the role of CNPase on both courses is unclear.

Effect of urinary alkalinisation and acidification on the tissue distribution of hexachlorophene in rats

1. Urinary alkalinisation may be helpful in treating acute poisoning with uncouplers of oxidative phosphorylation containing a phenolic hydroxyl (pKa 4-6) or other acidic moiety. 2. We studied the effects of urine alkalinisation and acidification on the tissue distribution of hexachlorophene (HCP, pKa 5.7) in male Sprague Dawley rats (10 rats/group). 3. Ammonium chloride (10 mL kg-1, 2% m/v) or sodium bicarbonate (10 mL kg-1, 2% m/v) were administered by gavage on three occasions over 24 h, prior to a single gavage dose of HCP (180 mg kg-1). Controls received aqueous sodium chloride (10 mL kg-1, 0.9% m/v) followed by either HCP (180 mg kg-1) or vehicle alone. 4. Urine pH, body mass and body temperature were monitored during the study and, at the conclusion of the experiment (12 h post-HCP dose), organ mass (liver, kidney, brain), and plasma, urine and tissue HCP concentrations were measured. 5. No clinical features of toxicity were observed in any group. However, sodium bicarbonate significantly reduced median HCP in liver--median plasma and kidney HCP concentrations were also reduced but not significantly. Conversely, ammonium chloride significantly increased median HCP concentrations in liver and kidney--median plasma HCP was also increased but not significantly. 6. The results provide some support for the hypothesis that blood pH influences the tissue distribution of uncouplers of oxidative phosphorylation containing an acidic moiety. Urinary alkalinisation may be useful in treating acute poisoning with these compounds.

A comparison of spongiosis induced in the brain by hexachlorophene, cuprizone and triethyl tin in the Sprague-Dawley rat

The effect of hexachlorophene (HCP; 2,2'-methylenebis(3,4,6-trichlorophenol), cuprizone (CPZ; bicyclohexone oxaldihydrazone) and triethyl tin (TET; triethyl tin sulphate) in producing vacuoles in the brain of the Sprague-Dawley rat has been quantified by image analysis of the extent of the spongy change in the white matter. The state of the astrocytes was assessed by immunocytochemical staining for glial fibrillary acidic protein (GFAP). HCP and TET caused a dose-related spongiosis, but cuprizone had no significant effect on the brain. With chronic HCP treatment, the spongiosis was accompanied by astrocyte hypertrophy and proliferation, and the extent of the gliotic reaction was related to the dose of HCP. The results demonstrate that HCP can produce and maintain astrocyte proliferation in the rat brain. Such an agent was required for use in an investigation of a putative tumour promoter in the rat.

Effects of chlorinated bisphenols on torula yeast glucose-6-phosphate dehydrogenase

Chlorinated bisphenol antibacterial and antifungal agents are potent inhibitors of torula yeast glucose-6-phosphate dehydrogenase (G6PD). Several compounds were tested, including hexachlorophene [HCP; 2,2'-methylenebis(3,4,6-trichlorophenol)]; 2,2'-oxybis(tetrachlorophenol); 2',4-dihydroxy-2,3,3',5,5',6-hexachlorodiphenylmethane; 2,2'-methylenebis(3,4-dichlorophenol) (3,4-TCP); bithionol [2,2'-thiobis(4,6-dichlorophenol)]; 2,2'-methylenebis(3,5-dichlorophenol); 2,2'-dihydroxy-3,3',5,6,6'-pentachlorodiphenylmethane; 2,2'-methylenebis(4-chlorophenol) (DCP); 2,2'-methylenebis(4,6-dichlorophenol); and the related uncoupler 2,4-dinitrophenol. The relative inhibitory activity of the chlorinated bisphenols tended to increase with degree of chlorination of the aromatic rings. the concentrations of the bisphenols that caused 50% inhibition ranged from 2.5 micrometers for 2,2'-oxybis(tetrachlorophenol) to 40 micrometers for 2,2'-methylenebis(4,6-dichlorophenol) under comparable assay conditions. More detailed kinetic analysis showed that, as with HCP, the inhibition of G6PD by 3,4-TCP and DCP followed noncompetitive kinetics. Calculations from the kinetic data gave apparent inhibition constant (Ki) values for 3,4-TCP of 267 micrometers with G6P and 308 micrometers with NADP, and for DCP of 697 micrometers with both G6P and NADP.

Changes in body temperature after administration of antipyretics, LSD, delta 9-THC, CNS depressants and stimulants, hormones, inorganic ions, gases, 2,4-DNP and miscellaneous agents

This survey concludes a series of complications of data from the literature, primarily published since 1965, on thermoregulatory effects of antipyretics in afebrile as well as in febrile subjects, LSD and other hallucinogens, cannabinoids, general CNS depressants, CNS stimulants including xanthines, hormones, inorganic ions, gases and fumes, 2,4-dinitrophenol and miscellaneous agents including capsaicin, cardiac glycosides, chemotherapeutic agents, cinchona alkaloids, cyclic nucleotides, cycloheximide, 2-deoxy-D-glucose, dimethylsulfoxide, insecticides, local anesthetics, poly I:poly C, spermidine and spermine, sugars, toxins and transport inhibitors. The information listed includes the species used, route of administration and dose of drug, the environmental temperature at which the experiments were performed, the number of tests, the direction and magnitude of body temperature change and remarks on the presence of special conditions such as age or lesions, or on the influence of other drugs, such as antagonists, on the response to the primary agents.

Hexachlorophene and the central nervous system. Toxic effects in mice and baboons

A study on hexachlorophene encephalopathy in mice and baboons is reported. By light microscopy, a severe spongiform lesion of the central nervous system (CNS) was localized in the white matter, without myelin breakdown or cellular reaction. By electron microscopy, the myelin alteration was characterized by wide intralamellar spaces or "splitting" developed in the intraperiod line of compact sheaths. The acute changes described were induced by administration of the drug by the digestive or cutaneous routes at various dosage levels in an aqueous solution or in talcum powder. The toxic effects depended on the age of the animals, the survival times and the concentrations of hexachlorophene, i.e., 6%, 3%, and 0.5%. The findings are compared with previous reports on the neurotoxicity of hexachlorophene and other chemicals in human and experimental animals. Hexachlorophene cannot be recommended for use in young infants because of its neurotoxicity in very low doses as demonstrated in the present report.

Percutaneous absorption of hexachlorophene in rats, guinea pigs and pigs

A comparative study of the percutaneous absorption of hexachlorophene (HCP) was undertaken in rats, guinea pigs and pigs. [14C]Hexachlorophene ([14C]HCP) was applied evenly over the shaved back of the animals at a dose of 40 microgram/cm2 skin surface. Urine and feces were collected at 24-h intervals for 5 days from animals kept in metabolism cages. Different methods were used for quantitating the percutaneous absorption of HCP. This study showed that skin permeability to HCP decreased in the following order: rat, guinea pig and pig. The permeability characteristics of the pig skin to topically applied HCP were comparable to the published human data. We suggest that pig may be a suitable animal model for studying the percutaneous absorption of antimicrobial drugs.

Experimental spongy degeneration in calves

Experimental reproduction and ultrastructural findings of spongy degeneration of the central nervous system of hyperammonemic calves are described. Hyperammonemia was produced by intravenous infusion of ammonium acetate. Histologic findings were stereotyped in all calves and characterized by widespread vacuolation of white and grey matter of the brain spinal cord. Electron microscopy revealed widespread intramyelinic vacuoles, some expansion of extracellular spaces and swollen mitochondria. There were minimal changes in neurons, axons and glia, and little evidence of myelin breakdown. Hyperammonemia may be one of the pathogeneses involved in the CNS spongy degeneration in man and domestic animals effected with hepatocerebral diseases and some hereditary disorders.

Hexachlorophene in mice. Effects after long-term percutaneous applications

The toxicity and carcinogenicity of life-time applications of hexachlorophene on the skin of Swiss mice were studied. Twice weekly applications of 0.02 ml of a 50% or 25% solution produced necrosis and ulceration of the skin as well as neurological symptoms and a mortality of up to 22% within two weeks. At autopsy, edema and cystic lesions were seen in the white matter of the central nervous system. The neurological symptoms were reversible, though a proportion of the cystic lesions persisted. Only one skin tumor was seen and the number of tumors of other organs, lymphomas, lung adenomas, liver hemangiomas, and other tumors, was not higher than in the controls. It is concluded from this study that percutaneous application of hexachlorophene has toxic local and systemic effects in mice, but no carcinogenic effects.