Cytochrome P450 induction in feral Cricetid rodents: a review of field and laboratory investigations

The palliative effect of camel milk on hepatic CYP1A1 gene expression and DNA damage induced by fenpropathrin oral intoxication in male rats

The present study investigated the alleviating role of camel milk (CM) in the mitigation of fenpropathrin (FNP) type II pyrethroid induced oxidative stress, alterations of hepatic (CYP1A1) mRNA expression pattern, and DNA damage using the alkaline comet assay (SCGE) in male rats. Sixty male Sprague-Dawley rats were separated into six groups (n = 10): 1st control (C), 2nd corn oil (CO), 3rd (CM): gavaged CM 2ml/rat, 4th (FNP): gavaged FNP 7.09 mg/kg body weight (BW), 5th (FNP pro/co-treated): gavaged CM firstly for 15 days, then CM + FNP by the same mentioned doses and route, 6th (FNP + CM co-treated): gavaged FNP firstly followed by CM by the same mentioned doses and route. Rats were orally gavaged three times per week, day after day for 60 days. FNP exposure significantly reduced serum glutathione (GSH) levels, but significantly increased serum levels of superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), protein carbonyl (PCO), and 8hydroxy2deoxyguanosine (8OH2dG). Additionally, FNP exposure significantly up-regulated the mRNA expression levels of hepatic CYP1A1 and increased the SCGE indices in whole blood, liver, and spleen tissues of exposed male rats. Administration of CM significantly regulated the FNP induced oxidative stress, reduced hepatic CYP1A1 mRNA expression levels and values of comet assay indices particularly in the (CM + FNP pro/co-treated) group compared to the (FNP + CM co-treated) group. In conclusion, our results indicate, for the first time, that FNP retains an in vivo genotoxic potential at a dose of (1/10 LD₅₀) and up-regulated hepatic CYP1A1 mRNA expression in male rats. Additionally, CM supplements may improve the genotoxic outcomes, oxidative stress, and altered CYP1A1 mRNA expression induced by FNP particularly in the pro/concurrent-treatment compared to the concurrent treatment alone.

Fecal shedding of zoonotic food-borne pathogens by wild rodents in a major agricultural region of the central California coast

Recent outbreaks of food-borne illness associated with the consumption of produce have increased concern over wildlife reservoirs of food-borne pathogens. Wild rodents are ubiquitous, and those living close to agricultural farms may pose a food safety risk should they shed zoonotic microorganisms in their feces near or on agricultural commodities. Fecal samples from wild rodents trapped on 13 agricultural farms (9 produce, 3 cow-calf operations, and 1 beef cattle feedlot) in Monterey and San Benito Counties, CA, were screened to determine the prevalence and risk factors for shedding of several food-borne pathogens. Deer mice (Peromyscus maniculatus) were the most abundant rodent species trapped (72.5%). Cryptosporidium species (26.0%) and Giardia species (24.2%) were the predominant isolates from rodent feces, followed by Salmonella enterica serovars (2.9%) and Escherichia coli O157:H7 (0.2%). Rodent trap success was significantly associated with detection of Salmonella in rodent feces, while farm type was associated with fecal shedding of Cryptosporidium and Giardia. Seasonal shedding patterns were evident, with rodents trapped during the spring and summer months being significantly less likely to be shedding Cryptosporidium oocysts than those trapped during autumn. Higher rodent species diversity tended to correlate with lower fecal microbial prevalence, and most spatiotemporal pathogen clusters involved deer mice. Rodents in the study area posed a minimal risk as environmental reservoirs of E. coli O157:H7, but they may play a role in environmental dissemination of Salmonella and protozoa. Rodent control efforts that potentially reduce biodiversity may increase pathogen shedding, possibly through promotion of intraspecific microbial transmission.

Pretreatment with Ginkgo biloba extract weakens the hypnosis action of phenobarbital and its plasma concentration in rats

In a previous study, we found that orally administered Ginkgo biloba extract (GBE) induced hepatic cytochrome P450 (CYP) in rats, especially the CYP2B type. This fact suggested that GBE influenced the availability and safety of drugs that were metabolized via CYP2B type enzymes. To confirm this possibility, in this study we examined the effect of feeding a 0.1, 0.5 and 1.0% GBE diet for 2 weeks on the pharmacokinetics and pharmacological action of phenobarbital, which is known to be metabolized by CYP2B in Wistar rats. The feeding of GBE markedly shortened the sleeping time in rats. Furthermore, the maximal phenobarbital plasma concentration (Cmax) and the 24-h area under the curve (AUC0–24) were decreased in rats fed GBE. These findings indicate that GBE reduces the therapeutic potency of phenobarbital via enhancement of cytochrome P450 expression, and raises the possibility that GBE and drug interactions may occur clinically.

Induction and recovery of hepatic drug metabolizing enzymes in rats treated with Ginkgo biloba extract

Herb-drug interactions, especially cytochrome P450 (CYP)-mediated interactions, cause an enhancement or attenuation in efficacy of co-administered drugs. In a previous study, we reported that repeated oral ingestion of Ginkgo biloba extract (GBE) markedly induced hepatic drug metabolizing enzymes in rats. In this study, we focused on the recovery of GBE-induced hepatic drug metabolizing enzymes after the discontinuation of GBE in rats. Feeding of a 0.5% GBE diet to rats for 1 week markedly increased liver weight, content of total CYP, activities of 6 CYP subtypes and glutathione S-transferase (GST). The content and activities of CYP enzymes were recovered to almost basal levels within 1 week after the discontinuation of GBE, while the activity of GST gradually decreased and recovered to the control level after 3 weeks. These results indicated that GBE-induced hepatic drug metabolizing enzymes in rats, especially CYPs, were rapidly recovered by discontinuation of GBE in rats even after excess treatment, and suggested that interactions of GBE with drugs could be avoided by discontinuation of GBE.

Dose-response relationships for cytochrome P450 induction by phenobarbital in the cotton rat (Sigmodon hispidus)

The induction of a hepatic pleiotropic response, including increase in liver/body weight ratio, induction of hepatic CYP2B and CYP3A protein and catalytic activity, and hepatic microsomal epoxide hydration activity, was investigated in male cotton rats (Sigmodon hispidus) administered graded dietary concentrations (0-1500 ppm) of phenobarbital (PB) for 14 days. A dose-dependent induction of each endpoint was observed, although plateaus in the various dose-response curves were not obtained, and ED50 values (PB concentrations associated with half-maximal responses) for the various endpoints were not able to be calculated. A maximal 1.31-fold increase, compared to the control value, in live/body weight ratio was observed, while microsomal epoxide hydration activity was increased as much as 3.6-fold by PB administration. Pentoxy- and benzyloxyresorufin O-dealkylation and testosterone 16 beta-hydroxylation activities (considered to be relatively selective for CYP2B in the Norway rat (Rattus norvegicus)), were induced maximally less than five-fold. Testosterone 6 beta-hydroxylation (considered to be relatively selective for CYP3A in R. norvegicus) was induced maximally less than two-fold. Maximal induction of 7-ethoxy-4-trifluoromethyl-coumarin O-deethylation was 18-fold, compared to the control rate. Western blotting studies indicated that hepatic microsomal proteins immunoreactive with polyclonal antisera to R. norvegicus CYP2B1 or CYP3A1 were induced, in a dose-responsive manner, by PB in the cotton rats. These results indicate that the cotton rat responds to PB treatment with a coordinate pleiotropic response similar to that displayed by R. norvegicus, although the substrate specificity of the induced proteins appears to differ between the two rodent species.