Effects of Imidacloprid on Histology and mRNA Levels of HSP70 and CYP1A Gene to a Standard Non-targeted Test Animal, Cyprinus carpio

Background: Imidacloprid (IMI) belongs to the class of neuro active insecticides, used to control pest and insects in agricultural crops. Reports suggest that IMI has highly toxic consequences on bees, humans and non-targeted aquatic animals. Hence the present study aims to investigate the toxicity effects of commercial-grade Imidacloprid (IMI) (Premise, 30.5%, a.i) using histological and transcriptional changes in heat shock protein 70 (HSP70) and cytochrome P4501A (CYP1A) genes in liver and gills of non-targeted aquatic animal, Cyprinus carpio. Methods: Three different sublethal concentrations of IMI (T1=26.04 mg/L, T2= 20.38 mg/L, T3=17.36 mg/L) were selected and common carp fingerlings were exposed for 28 days where histological alterations and expression study of HSP70 and CYP1A in gills and liver of exposed fishes being studied on 7, 14, 21 and 28 days interval using standard procedure. Result: Marked histological alteration like hydropic degeneration and cellular infiltration in liver; telangiectasis in secondary lamellae, epithelial lifting and oedema in gills were recorded. Moreover, significant upregulation of HSP70 and CYP1A gene in the gills and liver in a dose and time dependent manner was observed (P<0.05). As a result of the current investigation, it is obvious that IMI could be a possible toxicant that affects fish at the tissue and gene level in dosage and time dependent ways, potentially influencing other physiological processes in the long term.