Male and female rats aged 3 and 18 months with food and water ad libitum were decapitated and trunk blood was collected in chilled tubes that contained or not heparin (10 μl/ml of blood) to obtain plasma and serum, respectively.
Commercial ELISA kits were used to measure leptin and adiponectin (EMD Millipore Corporation, Billerica, MA, USA), insulin (Alpco, Salem, NH, USA), TSH (Crystal Chem, Grove Village, IL, USA) and T3 concentration (MyBioSource, San Diego, CA, USA).
CORT was extracted from 25 μl of plasma with 1 ml of ethanol. The hormone measurements were performed using specific radioimmunoassay (RIA) techniques described in the literature (Glucocorticoids et al.,1978 ). All measurements were performed in duplicate in the same assay. The sensitivity of the assay and the coefficient of variation intra‐assay were, respectively, 7.8 ng/dl and 4.6% for CORT.
Plasma prolactin (PRL) concentration was determined by RIA, using antibody provided by the National Hormone and Peptide Program (Harbor‐UCLA Medical Center, CA, USA). The lowest limit of detection was 0.10 ng/ml, intra‐assay coefficient of variation was 2.5%.
Commercial ELISA kits were used to measure leptin and adiponectin (EMD Millipore Corporation, Billerica, MA, USA), insulin (Alpco, Salem, NH, USA), TSH (Crystal Chem, Grove Village, IL, USA) and T3 concentration (MyBioSource, San Diego, CA, USA).
CORT was extracted from 25 μl of plasma with 1 ml of ethanol. The hormone measurements were performed using specific radioimmunoassay (RIA) techniques described in the literature (Glucocorticoids et al.,
Plasma prolactin (PRL) concentration was determined by RIA, using antibody provided by the National Hormone and Peptide Program (Harbor‐UCLA Medical Center, CA, USA). The lowest limit of detection was 0.10 ng/ml, intra‐assay coefficient of variation was 2.5%.