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Effect of enrofloxacin on AgNOR counts in chick bone marrow nuclei
1Department of Zoology, Government Science College, Jabalpur-482001, India. ikkhanna@bom6.vsnl.net.in
Abstract:
The mAgNOR and pAgNOR counts reflecting the number of rDNA genes being transcribed, showed a highly significant increase from control values following administration of 5X, 10X, 15X doses of enrofloxacin in chicken. The maximum increase for both, mAgNOR and pAgNOR was shown by birds receiving 15X dose, sacrificed 48 hr after the last drug injection. The increase of pAgNOR at 5X (24 hr) was not significant relative to control values. After 72 hr time interval, AgNOR counts were not feasible due to poor differentiation. Values at 15X (24 hr) showed a decrease in number of AgNOR counts (non-significant) relative to 10X, probably due to depression of transcriptional activity of rDNA genes, which, however, is removed at 48 hr. The general increase in mAgNOR and pAgNOR with dose reflects hypertranscription of rDNA genes so that the birds can cope up with the drug induced toxicity.
Insights
Enrofloxacin treatment significantly increased nucleolar organizer region counts in chickens, indicating enhanced ribosomal DNA gene transcription. This response suggests a cellular mechanism to counteract drug-induced toxicity.
Area of Science:
- Veterinary Pharmacology
- Molecular Biology
- Cellular Toxicology
Background:
- Nucleolar organizer regions (NORs) are associated with ribosomal DNA (rDNA) gene transcription.
- AgNOR staining quantifies the activity of these genes.
- Enrofloxacin is a fluoroquinolone antibiotic used in veterinary medicine.
Purpose of the Study:
- To investigate the effect of varying enrofloxacin doses on rDNA gene transcription in chickens.
- To assess the dose-dependent and time-dependent changes in nucleolar organizer region (NOR) counts.
Main Methods:
- Chickens were administered 5X, 10X, and 15X doses of enrofloxacin.
- Nucleolar organizer region (mAgNOR and pAgNOR) counts were assessed at 24 and 48 hours post-injection.
- AgNOR counts were evaluated for statistical significance compared to control groups.
Main Results:
- A highly significant increase in mAgNOR and pAgNOR counts was observed with increasing enrofloxacin doses (5X, 10X, 15X).
- The 15X dose showed the maximum increase in AgNOR counts at 48 hours.
- A transient, non-significant decrease in AgNOR counts at 15X (24 hr) suggested temporary transcriptional depression, which recovered by 48 hours.
Conclusions:
- Enrofloxacin administration induces hypertranscription of rDNA genes in chickens, as evidenced by increased AgNOR counts.
- This transcriptional upregulation is likely a cellular adaptive response to manage enrofloxacin-induced toxicity.
- The findings highlight the impact of fluoroquinolone antibiotics on cellular gene expression in poultry.