Methods for the estimation of acetylcholinesterase activity in the plasma and brain of laboratory animals given carbamates or organophosphorus compounds

Dose Dependent Effects of Breynia cernua Against the Paraquat Induced Parkinsonism like Symptoms in Animals' Model: In Vitro, In Vivo and Mechanistic Studies

The aims and objectives of the study were to evaluate the antiParkinson's (PD) potential of B cernua (BCE). B cernua (Poir.) Müll. Arg. (B cernua) is a member of the Phyllanthaceae family. HPLC revealed the presence of various phytochemicals. Study was conducted for 40 days. After PD induction by paraquat behavioural studies were carried out. Biochemical parameters such as DPPH, NO-scavenging, Ferrous reducing power, MDA, GSH, CAT, SOD, acetylcholinesterase (AChE), neurotransmitter estimation and TNF-α and IL-6 levels were determined. DPPH, NO-scavenging and Ferrous reducing power assays showed 78.02%, 48.05% and 71.45% inhibitions, respectively. There was significant improvement in motor functions and coordination in a dose-dependent manner (50 < 250 < 500 mg/kg) in PD rat model. Biochemical markers; SOD, CAT, GPx and GSH showed significant restoration (P < .001) while MDA showed significant decrease (P < .05). The AChE level was significantly reduced (P < .05) at 500 mg/kg while neurotransmitters were significantly improved (P < .001) in a dose-dependent fashion. The ELISA results showed significant (P < .001) down-regulation of IL-6 and TNF-α level. In conclusion, it is suggested that BCE has the potential to reduce the symptoms of PD.

Plasma cholinesterase activity of rats, western grey kangaroos, alpacas, sheep, cattle, and horses

INTRODUCTION

Plasma cholinesterase activity levels of various species may be of interest to toxicologists or pathologists working with chemicals that interfere with the activity of plasma cholinesterase.

METHODS

We used a pH titration method to measure the plasma cholinesterase activity of six mammalian species.

RESULTS

Plasma cholinesterase activity varied up to 50-fold between species: sheep (88 ± 45 nM acetylcholine degraded per ml of test plasma per minute), cattle (94 ± 35), western grey kangaroos (126 ± 92), alpaca (364 ± 70), rats (390 ± 118) and horses (4539 ± 721).

DISCUSSION

We present a simple, effective technique for the assay of plasma cholinesterase activity levels from a range of species. Although labour-intensive, it requires only basic laboratory equipment.

Determination of erythrocyte-bound acetylcholinesterase activity for monitoring pyridostigmine therapy in myasthenia gravis

Monitoring of pyridostigmine therapy in patients with myasthenia gravis is not routinely performed, since the daily pyridostigmine doses are adjusted to the patient's actual clinical status rather than to pyridostigmine plasma concentrations (PPC). Moreover, PPC determination is time-consuming and needs much technical equipment. Since pyridostigmine reversible blocks acetylcholinesterase (AChE) at the neuromuscular junction, we studied the correlation between the enzyme's blood activity (erythrocyte-bound AChE) and PPC, on the one hand, and between blood AChE activity and the clinical status of the individual patient, on the other. In five previously untreated patients with myasthenia gravis blood AChE activity decreased in accordance with the actual PPC after a single oral dose of 60 mg pyridostigmine (group A). Amelioration of the clinical status corresponded to the decrease of AChE activity in the same way. In another five patients, who were on stable pyridostigmine medication for at least 1 week, AChE activity and PPC were constant during the day (group B). Since it is easier to perform than PPC, our results suggest that the determination of AChE activity may be superior to measuring PPC for monitoring cholinesterase inhibitor therapy in selected cases.

Modification of triorthotolyl phosphate toxicity in chickens by stress

Chickens housed for 4.5 months in an environment of either low social stress or high social stress were administered triorthotolyl phosphate (TOTP) 180 mg/kg po. Clinical signs of delayed neuropathy were less in the low social stress group, unless moved to a high stress environment 24 hr before TOTP administration. Neurotoxic esterase activity was less than 20% of control values in all treatment groups. Birds from the low social stress group moved 24 hr prior to TOTP were more susceptible to inhibition of brain and liver cholinesterase activities following organophosphate administration. Liver microsomal enzyme activities (O-demethylase and aniline hydroxylase) were lowest in unmoved low social stress birds after TOTP, possibly protecting these birds from delayed neuropathy by reducing conversion of this organophosphate to its active metabolite.

A study on the toxicity and the biochemical effects of ethylene dibromide in the Japanese quail

1. The acute oral LD50 and chronic LC50 toxicity values for ethylene dibromide (EDB) were estimated for japanese quail. 2. Single sub-acute oral and intraperitoneal doses of EDB (1/2 LD50) and chronic oral doses of EDB (1/3 LC50) were administered to quail in order to characterise the sub-lethal effects of EDB residues. 3. At 24 h after sub-acute dosing, relative liver weight, plasma aspartate aminotransferase (AT) [EC 2.6.1.1] and L-iditol (sorbitol) dehydrogenase (SDH) [EC 1.1.1.14] were elevated and decreases were found in hepatic total lipid, total protein, AT and glutamic dehydrogenase (NAD (P)+) (GDH) and plasma cholinesterase (ChE) [EC 3.1.1.8] and total lipid. 4. Following chronic administration, elevations in relative liver weight, plasma ChE and total lipid, haemoglobin and haematocrit were found and hepatic AT, GDH and total lipid were decreased. 5. The changes in hepatic and plasma enzymes and constituents are discussed in relation to possible biphasic effects resulting from EDB exposure.

Dichlorvos -- a 2-year inhalation carcinogenesis study in rats

To determine the effects of dichlorvos vapour on the tumour incidence in rats, 5 week old Carworth Farm E strain rats weighing between 94 and 150 g were exposed to 0, 0.05, 0.5 and 5.0 mg/m3 in a 2-year inhalation study. The growth rate of all treated rats was depressed, particularly in the males. There was increased survival of the rats exposed to 5 mg/m3. There were no consistent differences in food intakes, organ weights, haematological or blood chemistry estimations, except in cholinesterase activites, amongst the various groups of rats. No compound-related differences were seen in acetylcholine and choline estimations carried out on a small number of female rats' brain tissues after two years' exposure. There were no gross or microscopical compound-related changes in the rats' tissues. Ultrastructural examination of the respiratory tissues of the rats from the control and 5 mg/m3 group showed no changes attributable to dichlorvos. The results of a relative risk analysis of the tumour data showed that no dose-related increase in tumour risk was established for rats of either sex. These data confirm the results of earlier st.udies supporting the safety of insecticidal uses of dichlorvos.