TY - JOUR
T1 - Impaired anterior swim bladder inflation following exposure to the thyroid peroxidase inhibitor 2-mercaptobenzothiazole part I
T2 - Fathead minnow
AU - Nelson, Krysta R.
AU - Schroeder, Anthony L.
AU - Ankley, Gerald T.
AU - Blackwell, Brett R.
AU - Blanksma, Chad
AU - Degitz, Sigmund J.
AU - Flynn, Kevin M.
AU - Jensen, Kathleen M.
AU - Johnson, Rodney D.
AU - Kahl, Michael D.
AU - Knapen, Dries
AU - Kosian, Patricia A.
AU - Milsk, Rebecca Y.
AU - Randolph, Eric C.
AU - Saari, Travis
AU - Stinckens, Evelyn
AU - Vergauwen, Lucia
AU - Villeneuve, Daniel L.
N1 - Publisher Copyright:
© 2016 Elsevier B.V..
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2016/4/1
Y1 - 2016/4/1
N2 - In the present study, a hypothesized adverse outcome pathway linking inhibition of thyroid peroxidase (TPO) activity to impaired swim bladder inflation was investigated in two experiments in which fathead minnows (Pimephales promelas) were exposed to 2-mercaptobenzothiazole (MBT). Continuous exposure to 1 mg MBT/L for up to 22 days had no effect on inflation of the posterior chamber of the swim bladder, which typically inflates around 6 days post fertilization (dpf), a period during which maternally-derived thyroid hormone is presumed to be present. In contrast, inflation of the anterior swim bladder, which occurs around 14 dpf, was impacted. Specifically, at 14 dpf, approximately 50% of fish exposed to 1 mg MBT/L did not have an inflated anterior swim bladder. In fish exposed to MBT through 21 or 22 dpf, the anterior swim bladder was able to inflate, but the ratio of the anterior/posterior chamber length was significantly reduced compared to controls. Both abundance of thyroid peroxidase mRNA and thyroid follicle histology suggest that fathead minnows mounted a compensatory response to the presumed inhibition of TPO activity by MBT. Time-course characterization showed that fish exposed to MBT for at least 4 days prior to normal anterior swim bladder inflation had significant reductions in anterior swim bladder size, relative to the posterior chamber, compared to controls. These results, along with similar results observed in zebrafish (see part II, this issue) are consistent with the hypothesis that thyroid hormone signaling plays a significant role in mediating anterior swim bladder inflation and development in cyprinids, and that role can be disrupted by exposure to thyroid hormone synthesis inhibitors. Nonetheless, possible thyroid-independent actions of MBT on anterior swim bladder inflation cannot be ruled out based on the present results. Overall, although anterior swim bladder inflation has not been directly linked to survival as posterior swim bladder inflation has, potential links to adverse ecological outcomes are plausible given involvement of the anterior chamber in sound production and detection.
AB - In the present study, a hypothesized adverse outcome pathway linking inhibition of thyroid peroxidase (TPO) activity to impaired swim bladder inflation was investigated in two experiments in which fathead minnows (Pimephales promelas) were exposed to 2-mercaptobenzothiazole (MBT). Continuous exposure to 1 mg MBT/L for up to 22 days had no effect on inflation of the posterior chamber of the swim bladder, which typically inflates around 6 days post fertilization (dpf), a period during which maternally-derived thyroid hormone is presumed to be present. In contrast, inflation of the anterior swim bladder, which occurs around 14 dpf, was impacted. Specifically, at 14 dpf, approximately 50% of fish exposed to 1 mg MBT/L did not have an inflated anterior swim bladder. In fish exposed to MBT through 21 or 22 dpf, the anterior swim bladder was able to inflate, but the ratio of the anterior/posterior chamber length was significantly reduced compared to controls. Both abundance of thyroid peroxidase mRNA and thyroid follicle histology suggest that fathead minnows mounted a compensatory response to the presumed inhibition of TPO activity by MBT. Time-course characterization showed that fish exposed to MBT for at least 4 days prior to normal anterior swim bladder inflation had significant reductions in anterior swim bladder size, relative to the posterior chamber, compared to controls. These results, along with similar results observed in zebrafish (see part II, this issue) are consistent with the hypothesis that thyroid hormone signaling plays a significant role in mediating anterior swim bladder inflation and development in cyprinids, and that role can be disrupted by exposure to thyroid hormone synthesis inhibitors. Nonetheless, possible thyroid-independent actions of MBT on anterior swim bladder inflation cannot be ruled out based on the present results. Overall, although anterior swim bladder inflation has not been directly linked to survival as posterior swim bladder inflation has, potential links to adverse ecological outcomes are plausible given involvement of the anterior chamber in sound production and detection.
KW - Adverse outcome pathway
KW - Cyprinid
KW - Endocrine disruption
KW - Fish early life stage
KW - Swim bladder
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U2 - 10.1016/j.aquatox.2015.12.024
DO - 10.1016/j.aquatox.2015.12.024
M3 - Article
C2 - 26852267
AN - SCOPUS:84958876580
SN - 0166-445X
VL - 173
SP - 192
EP - 203
JO - Aquatic Toxicology
JF - Aquatic Toxicology
ER -