N-acetyltransferase Enzyme Activity Research Articles

Визначення біохімічної активності ферменту N-ацетилтрансферази, продукції гена NAT2 у дітей з екопатологією після проведеної терапії

Вивчення біохімічної активності ферменту N-ацетилтрансферази, продукції гена NAT2 у дітей з екологічно несприятливих регіонів (ЕНР) є надзвичайно важливим для виявлення схильності до екопатології, зокрема до захворювань щитоподібної залози, нирок та органів сечовивідної системи в умовах забрудненого довкілля. Прикладом такого регіону є хімічно забруднені Галицький, Долинський і Калуський райони та радіологічно забруднений Снятинський район Івано-Франківської області. Було обстежено 239 дітей з ЕНР та 70 дітей із групи контролю. Вік дітей — від 3 до 18 років, стать: хлопці — 48 %, дівчата — 52 %. Всі діти оглянуті клінічно, їм проведена інструментальна (УЗД, ультразвукова денситометрія) та лабораторна діагностика до й після терапії. Біохімічним методом визначена активність ферменту N-ацетилтрансферази. Низька активність ферменту, що кодується геном NAT2, у дітей з екопатологією обумовлює їх низьку здатність до ацетилювання, що є підґрунтям для формування екозалежних захворювань щитоподібної залози, кісток і нирок у цих дітей. Мембранопротекторна, антиоксидантна, сорбційна терапія та застосування препаратів кальцію мають виражений позитивний ефект щодо активності ферменту N-ацетилтрансферази у крові обстежених дітей.

Δ<sup>9</sup>-Tetrahydrocannabinol Produced Positive Place Preference in Mice without Significant <i>Ex-Vivo</i> Effect on Hepatic Arylamine N-Acetyltransferase Activity: Implications for Its Addictive Liability and Absence of Effect on Xenobiotic Metabolism

Aim: Δ9-Tetrahydrocannabinol (Δ9-THC) is a potentially addictive cannabinoid. Its impact on the activity of liver arylamine N-Acetyltransferase (NAT) has not been reported. This study investigated the rewarding effects of Δ9-THC in mice and whether Δ9-THC had any impact ex-vivo and in-vitro on NAT activity. Methods: Thirty-six Swiss albinomice randomly assigned to six groups (n = 6) completed a biased, 8-week Conditioned Place Preference (CPP) paradigm. Mice exhibiting ~80% preference for the black chamber at pre-conditioning were selected. Treatment groups were administered Δ9-THC (0.10, 0.50 or 2.0 mg/kg/mL, ip) or amphetamine (AMP, 5.0 mg/kg/mL, ip); while untreated groups (controls) received vehicle solutions (coconut oil or 0.9% saline). Entries and time spent in the white, drug-paired chamber during a 15-min post-conditioning exploration of the CPP apparatus were compared with the pre-conditioning exploratory scores. Livers from Δ9-THC treated and untreated mice were excised and NAT enzyme activity determined ex-vivo using a spectrophotometric assay with p-anisidine as substrate. The impact of varying concentrations of Δ9-THC (0.00 - 162 μM) on the activities of NAT from untreated mice livers were also investigated in-vitro. Results: Δ9-THC treated mice entered and spent significantly more time in the drug-paired CPP chamber (p ≤ 0.05) at post-conditioning vs pre-conditioning (F = 11.22). Mice treated with 2.0 mg/kg Δ9-THC made significantly more entries into the drug-paired chamber (p ≤ 0.05) as compared with their vehicle controls. AMP-treated mice displayed significant (p In-vitro NAT evaluations revealed a dose-dependent inhibitory impact of Δ9-THC on NAT activity with an IC50 value of 34.97 ±1.58 μM. Ex-vivo evaluations of livers from Δ9-THC treated mice showed no significant impact on liver NAT enzyme activity. Conclusion: Δ9-THC induced significant conditioned place preference (drug reward) and produced a moderate dose-dependent inhibition on NAT activity in-vitro, but not ex-vivo.

Paclitaxel (taxol) inhibits the arylamine N-acetyltransferase activity and gene expression (mRNA NAT1) and 2-aminofluorene-DNA adduct formation in human bladder carcinoma cells (T24 and TSGH 8301).

Acetylator polymorphism in man results from differential expression of human liver N-acetyltransferase. N-Acetyltransferase enzyme activity has been demonstrated to be involved in some types of chemical carcinogenesis. Paclitaxel (taxol) had been shown to affect N-acetyltransferase activity of human lung cancer cells. In this study, paclitaxel was chosen to investigate the effects of arylamine N-acetyltransferase activity (N-acetylation of substrate), gene expression and 2-aminofluorene-DNA adduct formation in human bladder carcinoma cell lines (T24 and TSGH 8301). The N-acetyltransferase activity (N-acetylation of substrates) was determined by high performance liquid chromatography assaying for the amounts of acetylated 2-aminofluorene and p-aminobenzoic acid and nonacetylated 2-aminofluorene and p-aminobenzoic acid. Intact human bladder carcinoma T24 and TSGH 8301 cells were used for examining N-acetyltransferase activity, gene expression and 2-aminofluorene-DNA adduct formation. The results demonstrated that the N-acetyltransferase activity, gene expression (NAT1 mRNA) and 2-aminofluorene-DNA adduct formation in intact human bladder carcinoma cells were inhibited and decreased by paclitaxel in a dose-dependent manner. The effects of paclitaxel on the apparent values of Km and Vmax of N-acetyltransferase enzyme from intact human bladder carcinoma cells were also determined in these cell lines. A marked influence of paclitaxel was observed on the decreasing apparent values of Km and Vmax from intact human bladder carcinoma cells (T24 and TSGH 8301). Thus, paclitaxel is an uncompetitive inhibitor to the NAT enzyme.

Acetylator status of kwashiorkor children in Ibadan (South-West Nigeria)

Acetylator status was determined in 25 kwashiorkor children, aged between 8 months and 3 years and in 25 age-matched control group of healthy children after a single oral dose of sulphamethazine (40 mg/kg body weight) and by measuring the acetylated sulphamethazine in blood samples, collected 6 h after the administration of sulphamethazine. The percentage of slow acetylators among kwashiorkor children was 40% while among the control group of children it was 48%. The difference between the two groups was not significant. Therefore, it is probable that the slow acetylator status of the Nigerian African children may not be a contributing factor for the development of kwashiorkor, a syndrome of protein-energy malnutrition. Furthermore, the polymorphic activity of N-acetyl transferase enzyme may not be impaired in kwashiorkor.

N-acetyltransferase and hydroxyindole-O-methyltransferase activity in intraocular pineal transplants: diurnal thythm as evidence for functional sympathetic adrenergic innervation.

Immature rat pineal grafts were transplanted bilaterally to the anterior eye chamber of adult male rats. The transplants matured and became sympathetically innervated from the host iris and synthesized 5-hydroxytryptamine as revealed by fluorescence histochemistry. Transplants were used to investigate whether the newly formed nerve terminals were functional and thus could induce a rhythm in pineal N-acetyltransferase (NAT) enzyme activity and hydroxyindole-O-methyl transferase (HIOMT) enzyme activity. The in situ pineal glands from the recipient animals exhibited NAT and HIOMT levels and diurnal variations of enzyme activities no different from control rats without transplants. Sympathetically innervated transplants showed lower NAT enzyme activity than the in situ pineals but did yield a highly significant increase in darkness NAT activity as compared to light NAT activity (20:1). Sympathetically denervated transplants showed a much smaller rise in darkness NAT enzyme activity as compared to light values (1.8:1) but the rhythm was still statistically significant (p less then 0.01). Sympathetically innervated transplants had a higher HIOMT activity in darkness than in light (2.7:1)9 The HIOMT activity of the sympathetically denervated grafts was invariably low. Protein contents of transplants were found to be significantly lower than in situ pineal protein content but failed to show a diurnal variation.