Concentration response profiles of zebrafish larvae exposed to MBV condensate from 6 to 72 hpf.

<p><b>A</b>) DMSO Carrier control (CC); <b>B-H</b>) 10, 15, 20, 25, 30, 40, 50 µg/mL CSC, respectively. Scale bars correspond to 280 µm.</p

Use of the Zebrafish Larvae as a Model to Study Cigarette Smoke Condensate Toxicity

<div><p>The smoking of tobacco continues to be the leading cause of premature death worldwide and is linked to the development of a number of serious illnesses including heart disease, respiratory diseases, stroke and cancer. Currently, cell line based toxicity assays are typically used to gain information on the general toxicity of cigarettes and other tobacco products. However, they provide little information regarding the complex disease-related changes that have been linked to smoking. The ethical concerns and high cost associated with mammalian studies have limited their widespread use for <i>in vivo</i> toxicological studies of tobacco. The zebrafish has emerged as a low-cost, high-throughput, <i>in vivo</i> model in the study of toxicology. In this study, smoke condensates from 2 reference cigarettes and 6 Canadian brands of cigarettes with different design features were assessed for acute, developmental, cardiac, and behavioural toxicity (neurotoxicity) in zebrafish larvae. By making use of this multifaceted approach we have developed an <i>in vivo</i> model with which to compare the toxicity profiles of smoke condensates from cigarettes with different design features. This model system may provide insights into the development of smoking related disease and could provide a cost-effective, high-throughput platform for the future evaluation of tobacco products.</p></div

Comparison of the toxicity profile of zebrafish larvae following exposure to cigarette smoke condensates (CSCs).

<p>Concentration response (ug/ml) of CSCs prepared using Health Canada Intense (HCI) smoking regime. Asterisk indicates no significant difference between cigarette types for the specific toxic parameter measured (f-test, p>0.05).</p><p>Comparison of the toxicity profile of zebrafish larvae following exposure to cigarette smoke condensates (CSCs).</p

Cerebal hemorrhaging in zebrafish larvae exposed to BSV condensate from 6–72 hpf.

<p><b>A</b>) DMSO Carrier control (CC); <b>B</b>) 12.5 µg/mL CSC. <b>C</b>) 20 µg/mL CSC. Arrows indicate blood pooling. Scale bars correspond to 280 µm.</p

Behavioural toxicity following exposure to the MBV condensate from 72–120 hpf.

<p>A) Larval response to 5 minute cycles of light-dark. B) Dark startle response presented as the difference between the light and dark response levels. C) Concentration response curve for dark response.</p

Changes in melanocyte patterning and distribution following cigarette smoke condensate (CSC) exposure from 48–72 hpf.

<p>A, C, E, G) DMSO Carrier control (CC). Changes in pigment distribution (arrows) within the melanphores of the eyes and yolksac (B), dorsal regions of the head (D) and the tail midline (F) following treatment with 50 µg/mL CSC prepared from 3R4F using the ISO smoking regime, are evident. Concentration-dependent change in melanocyte morphology and pigment level (arrows) following exposure to CSC prepared from the Canadian best seller (BSV) using the ISO smoking regime (H-6.1 µg/mL; I-50 µg/mL). Scale bars in A, C and E correspond to 280, 70 and 80 µm, respectively.</p

Changes in heart rate following larval exposure to cigarette smoke condensates (CSCs) from 24–48 hpf.

<p>CSCs were prepared under the International Organization for Standardization (ISO) and Health Canada Intense (HCI) smoking regimes. bpm = beats per minute.</p><p><i>Note</i>. Concentrations of CSC: ^a25 µg/mL; ^b50 µg/mL; ^c30 µg/mL; ^d15 µg/mL; ^e20 µg/mL; ^f40 µg/mL.</p><p>Changes in heart rate following larval exposure to cigarette smoke condensates (CSCs) from 24–48 hpf.</p

Characteristics of Cigarettes Selected for the Study.

<p><i>Note.</i>^aISO = International Organization for Standardization smoking condition; ^b = Health Canada Intense smoking condition; ^c =  PM =  Total Particulate Matter; ^dMixed blend refers to a tobacco blend of different tobacco types.</p><p>Characteristics of Cigarettes Selected for the Study.</p

Gene expression changes (fold change) following larval exposure to the MBV condensate from 72 to 77 hpf as measured by qPCR.

<p>Significant changes in gene expression are indicated with an asterisk. Cigarette some condensates were prepared under the International Organization for Standardization (ISO) and Health Canada Intense (HCI) smoking regimes.</p><p>Gene expression changes (fold change) following larval exposure to the MBV condensate from 72 to 77 hpf as measured by qPCR.</p