TY - JOUR
T1 - The effect of flight, fasting and p,p′-DDT on thyroid hormones and corticosterone in Gambel's white-crowned sparrow, Zonotrichia leucophrys gambelli
AU - Scollon, Edward J.
AU - Carr, James A.
AU - Cobb, George P.
N1 - Funding Information:
This work was supported by The Institute of Environmental and Human Health, Texas Tech University, Plum Foundation, and the National Institutes of Health Sciences. Wind tunnel facilities were provided by Dr Cliff Fedler of the Wind Engineering Department, Texas Tech University.
PY - 2004/2
Y1 - 2004/2
N2 - This study examined the effects of p,p′- dichlorodiphenyltrichloroethane (p,p′-DDT), fasting and flight on thyroid hormones and corticosterone in Gambel's White-crowned Sparrows (Zonotrichia leucophrys gambelli). Female sparrows were dosed daily with either 5 mg p,p′-DDT per kg body mass or corn oil vehicle over 3 days. On the fifth day the sparrows were divided into 3 groups: (1) unstressed - non-stressed control sparrows; (2) fasted - sparrows fasted for intervals ranging from 20 min to 9 h; or (3) flown - sparrows flown in a wind tunnel for intervals between 20 min and 2.5 h while fasting. Half the sparrows from each group received DDT (DDT-dosed sparrows) and the other half corn oil vehicle only (vehicle sparrows). Trunk blood plasma was analyzed for thyroxine, triiodothyronine and corticosterone using radioimmunoassay. In the flown group, corticosterone was elevated (DDT-dosed 35.52 ng/ml, P≤0.05), and thyroxine was depressed (DDT-dosed 4.09 ng/ml, P≤0.05; vehicle 4.33 ng/ml, P≤0.05). Elevated corticosterone likely decreased thyroid hormone production through a negative feedback mechanism originating at the hypothalamus. Mean triiodothyronine concentrations did not differ among any of the test groups. Relative to time fasted and flown, thyroxine decreased in flown birds dosed with DDT (P<0.001) and triiodothyronine decreased in fasted birds dosed with DDT (P=0.004). The increased rate of hormone diminution may be a result of the ability of DDT to induce microsomal enzyme production.
AB - This study examined the effects of p,p′- dichlorodiphenyltrichloroethane (p,p′-DDT), fasting and flight on thyroid hormones and corticosterone in Gambel's White-crowned Sparrows (Zonotrichia leucophrys gambelli). Female sparrows were dosed daily with either 5 mg p,p′-DDT per kg body mass or corn oil vehicle over 3 days. On the fifth day the sparrows were divided into 3 groups: (1) unstressed - non-stressed control sparrows; (2) fasted - sparrows fasted for intervals ranging from 20 min to 9 h; or (3) flown - sparrows flown in a wind tunnel for intervals between 20 min and 2.5 h while fasting. Half the sparrows from each group received DDT (DDT-dosed sparrows) and the other half corn oil vehicle only (vehicle sparrows). Trunk blood plasma was analyzed for thyroxine, triiodothyronine and corticosterone using radioimmunoassay. In the flown group, corticosterone was elevated (DDT-dosed 35.52 ng/ml, P≤0.05), and thyroxine was depressed (DDT-dosed 4.09 ng/ml, P≤0.05; vehicle 4.33 ng/ml, P≤0.05). Elevated corticosterone likely decreased thyroid hormone production through a negative feedback mechanism originating at the hypothalamus. Mean triiodothyronine concentrations did not differ among any of the test groups. Relative to time fasted and flown, thyroxine decreased in flown birds dosed with DDT (P<0.001) and triiodothyronine decreased in fasted birds dosed with DDT (P=0.004). The increased rate of hormone diminution may be a result of the ability of DDT to induce microsomal enzyme production.
KW - Chromohelicase-DNA- binding (CHD) gene
KW - Corticosterone
KW - Fasting
KW - Flight
KW - Thyroxine
KW - Triiodothyronine
KW - White-crowned sparrow
KW - Wind tunnel
KW - p,p′-dichlorodiphenyltrichloroethane
UR - http://www.scopus.com/inward/record.url?scp=1642288965&partnerID=8YFLogxK
U2 - 10.1016/j.cca.2004.01.004
DO - 10.1016/j.cca.2004.01.004
M3 - Article
C2 - 15050929
AN - SCOPUS:1642288965
SN - 1532-0456
VL - 137
SP - 179
EP - 189
JO - Comparative Biochemistry and Physiology - C Toxicology and Pharmacology
JF - Comparative Biochemistry and Physiology - C Toxicology and Pharmacology
IS - 2
ER -