A combination insecticide at sub-lethal dose debilitated the expression pattern of crucial signalling molecules that facilitate craniofacial patterning in domestic chick Gallus domesticus

• Published in: Neurotoxicology and teratology Vol. 76; p. 106836
• Main Authors: Sharma, Shashikant, Uggini, Gowri K., Desai, Isha, Balakrishnan, Suresh
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.2019
• Subjects: Animals; Beak - abnormalities; BMP; Brain Chemistry - drug effects; Chick Embryo; Chickens; Chlorpyrifos - toxicity; Combination insecticide; Craniofacial Abnormalities - chemically induced; Craniofacial Abnormalities - mortality; Craniofacial Abnormalities - physiopathology; Craniofacial malformation; Female; Gene Expression Regulation, Developmental - drug effects; Hydroxyproline - metabolism; Insecticides - toxicity; Pregnancy; Prenatal Exposure Delayed Effects; Pyrethrins - toxicity; RNA, Messenger - biosynthesis; RNA, Messenger - genetics; SHH; Signal Transduction - drug effects; Signal Transduction - genetics; WNT; Chick embryo; Combination insecticide; SHH; BMP; WNT; Craniofacial malformation
• ISSN: 0892-0362; 1872-9738
• DOI: 10.1016/j.ntt.2019.106836

Pesticides despite being agents that protect the plants and humans from noxious pests, are infamous for their potential to cause detrimental health issues in nontargeted species. In order to ascertain the latter, a set of experiments were conducted by exposing early chick embryos to a widely used combination insecticide (Ci, 50% chlorpyrifos and 5% cypermethrin). The results revealed a myriad of congenital defects pertaining to craniofacial development such as anophthalmia, microphthalmia, exencephaly as well as deformed beak and cranial structures. These teratological manifestations could be attributed to the Ci induced alteration in the titre of major regulators of neurulation and ossification. Therefore, the mRNA and/or the protein level expression pattern of genes which are reported to be involved in the craniofacial development were studied at selected time points of embryonic development. The analysis of the result showed that there have been significant alternations in the expression patterns of the signalling molecules such as SHH, WNTs, CDH1, CDH2, L1CAM, PAX6, HOX, PCNA, GLI3, BMP7, FGF8, GLIs, SOX9, RUNX2, DLX5, COL10A1, CASPASE3 etc. on embryonic days 2, 4 and/or 10. Concurrently, on day 10, whole-mount skeletal staining and biochemical estimation of hydroxyproline were carried out in the cranial tissues of the embryos. The overall result of the current study indicates that exposure to Ci during early development impede the crucial regulatory signals that orchestrate the morphogenesis of cranial neural crest cells thereby hindering the normal progression of neural tube and endochondral ossification which collectively lead to craniofacial dysmorphism in domestic chicks. •Exposure to combination insecticide led to reduction in the size of head of day 2 embryos.•Brain lobe formation was hampered at day 4 upon Ci treatment.•Chondrogenesis and endochondral ossification pattern was disturbed in day 10 embryo.•Ci altered the expression of signalling molecules that regulate craniofacial patterning.