Phosvel is an organophosphorus pesticide known to produce delayed neurotoxicity. In our earlier investigation, the neurotoxicity was greater in hens which fasted for two weeks than in those which were normally or force fed for some weeks. This suggested a relationship between the sensitivity to the neurotoxicity of phosvel and the amount of adipose tissue of animals receiving this compound.
In this study, neurotoxicity levels in five groups of hens, each fasted for different duration (3, 6, 9, 12 and 15 days) before administration of phosvel, were compared with normally fed hens. The results are as follows;
1. A single oral dose of phosvel was administered to each hen at the rate of 250 mg/kg body weight.
2. There were no abnormal hens in the fed group or the ‘3 days fasting’ group.
3. In the ‘6 days fasting’ group, 2 out of 5 hens showed ataxia and one of them developed mild paralysis. But no hens died in this group.
4. However, in both groups of ‘9’ and ‘15 days fasting’, all hens were attacked by delayed neurotoxic effect. Three out of five in each group died after developing severe paralysis.
5. One bird in the ‘12 days fasting’ group died due to the acute poisoning of phosvel on day 3 after administration. This was a very rare case in the series of studies of the compound. Three out of 4 remaining hens developed severe paralysis and one of these affected hens died.
6. In general, the longer the animals fasted the greater was the delayed neurotoxic effect, however, if the adipose tissue of the animals was cosumed more than a certain level by enforced fasting, the neurotoxicity tended to be markedly increased.

To determine whether the ethlenbisdithiocarbamate fungicides, zineb, manzeb and maneb affect the N-methyl-D-aspartate (NMDA) receptor in rat brain membranes, we performed a binding assay using [3H]MK-801, a noncompetitive NMDA receptor antagonist. Displacement studies were conducted using well washed membranes to exclude the effect of endogenous acidic amino acids on the binding of [3H]MK-801. In both the presence or absence of added glutamate and glycine in the assay buffer, the dose-response curve indicated that zineb enhanced the binding in a concentration range of 100-500 μM. However, the displacement curves indicated that manzeb and maneb inhibited the binding in a concentration range of 10-500 μM. The addition of 50 μM glutamate and glycine to the assay medium increased binding by 5-20% above the control in a concentration range of 0.1-100 μM. No rats injected with zineb, manzeb, maneb (100 mg/kg, ip) showed any characteristic toxic signs or any significant weight changes within 24 hrs. Estimation of [3H]MK-801 binding to unwashed membranes from intoxicated rat brains revealed no marked change in Bmax or Kd values for 24 hrs following fungicide administration.
binding ; Upper case emm ; Fungicide, NOS ; MK-801 ; assay

An organophosphorus insecticide EPN, O-ethyl-O, 4-nitrophenyl phenylphosphonothioate, is a stronger inhibitor of ChE activity than leptophos or cyanofenphos which are delayed neurotoxic organophosphorus insecticides, and it is usually difficult to demonstrate its delayed neurotoxicity with a single oral dose without atropinization. In this study, delayed neurotoxic effect of EPN was observed in non-atropinized hens by using the repeated pretreatment method.
1) Three groups of hens were given preliminarily small dose of EPN such as 10mg/kg/day for 10 days, 5 mg/kg/day for 20 days and 10mg/kg/day for 20 days. Another group was not given any preliminary dose. After each pretreatment, these groups received a large amount of dose called ‘challenge dese’, 150mg/kg, 200mg/kg or 300mg/kg of EPN. During the pretreatmental period, only 2 out of 60 hens which received the pretreatment died.
2) The mortality rate due to the acute toxicity after the challenge does in the group pretreated by 10 mg/kg/day for 20 days was significantly lower than in the non-pretreated group.
3) It is clear that EPN shows delayed neurotoxicity in hens. Delayed neurotoxic effect was observed in all groups which were given repeatedly the pretreatment of EPN prior to each challenge dose. While the survived hens from the acute death in the non-pretreated group did not show any sign of delayed neurotoxicity. The specific relationship, however, was not observed between the anount and times of pretreatment and the incidence of delayed neurotoxicity.
4) Delayed neurotoxic effects of EPN such as clinical symptomes, the cource of body-weight change and the findings of histopathological changes were just similar to those of leptophos and cyanofenphos.
5) The results of this study suggest that the using of the repeated pretreatment method allows to give high concentrated organophosphorus compound without atropinization and to accurate assessment of delayed neurotoxicity of some organophosphates; these effects would otherwise not be detected using a single dose of LD₅₀.

OBJECTIVETributyltin (TBT) compounds have been widely used as antifouling agents for shipbottom paint. The immune system is a target of TBT intoxication. We evaluated the effects of TBT chloride in macrophages, which have critical roles in the immune system, using a murine macrophage lineage cell line, J774.1,in vitro.

METHODSWe examined tumor necrosis factor α (TNFα), interleukin-1β (IL-1β) andc-jun mRNA expression in J774.1 cells. The effects of TBT on the apoptosis of J774.1 cells were examined by determining the percentage of TUNEL-positive cells and caspase-3 activity.

RESULTSThe mean values of the viabilities of J774.1 cells exposed to TBT decreased dose-dependently. The relative mRNA expression of TNFα increased dose-dependently, however, that of IL-1β was not significantly different among the groups. The mean percentage of TUNEL-positive cells increased dose-dependently. Increases in the caspase-3 activities of J774.1 cells were observed in the groups exposed to higher concentrations of TBT. The mean value of relative mRNA expression of c-Jun transcription factor increased dose-dependently.

CONCLUSIONSThe increases in the percentage of TUNEL-positive cells and in caspase-3 activity suggested that exposure to TBT induces apoptosis of J774.1 cells. The increases in the mRNA expression of TNFα andc-jun by TBT may be related to apoptosis in macrophages.

OBJECTIVEThe aim of this study was to investigate the effect of tributyltin (TBT) compound onN-methyl-D: -aspartate (NMDA) receptors in the brains of preweanling mice.

METHODSPregnant ICR mice were exposed to TBT chloride at concentrations of 0, 15, and 50 ppm in water. Male offspring were sacrificed at 1, 2 and 3 weeks after birth. Mouse brain membranes were prepared from cerebral cortices, and the specific binding of [(3)H]MK-801 to an NMDA receptor was determined by radioligand binding assay.

RESULTSThe mean body weight of preweanling mice of the 50 ppm dose group decreased by 17-25% (p<0.01) at 1, 2 and 3 weeks of age, compared with that of preweanling mice of the corresponding control group. The [(3)H]MK-801 binding level significantly decreased (p<0.05) in the 15 ppm F1 group at 1 week and in the 15 ppm and 50 ppm F1 groups at 3 weeks of age, compared with that in the corresponding control F1 group.

CONCLUSIONSThe exposure to TBT via placenta and dam's milk seriously affected not only the growth of preweanling mice, but also the F1 cerebral NMDA receptors involved in memory and learning.