Endocrine Abstracts

There are many theories regarding the function of UCP3, including transportation of fatty acids out of the mitochondria and production of reactive oxygen species. The function of UCP3 may influence the development of obesity and diabetes mellitus. In rodents UCP3 mRNA levels increase after T(sub)3(/sub) treatment. The ancient Meishan breed has enhanced neonatal survival rates than lean commercial breeds (C). Previous studies have demonstrated that plasma T(sub)3(/sub) is lower in Meishan piglets at birth. beta-adrenoreceptor agonists have been shown to improve temperature regulation in both rodents and sheep. This study investigated the influence of T(sub)3(/sub), methimazole (blocker of thyroid hormone) and a beta-agonist on UCP3 mRNA expression in piglet AT.

17 Commercial and 19 Meishan piglets entered the study. They were randomly assigned to treatment groups at birth; control (C:n=6, M:n=7), beta (C:n=6, M:n=6), methimazole (commercials only, n=5) and T(sub)3(/sub) (Meishans only, n=6). All animals received treatment for 4 days and were humanely euthanised afterwards. Plasma T(sub)3(/sub)was measured using an RIA. UCP3 mRNA expression was measured using RT-PCR as previously reported (Mostyn et al; 2004, Journal of Endocrinology, in press). GLM analysis was performed and results are presented as means ± standard errors.

T(sub)3(/sub) levels were increased in the T(sub)3(/sub) group throughout the study (control: 1.9±0.14 nanogram per millilitre; T(sub)3(/sub) 11.7±3.11 nanogram per millilitre).UCP3 expression was higher in Meishans than in commercials (P<0.05). UCP3 expression was lower in the Meishan T(sub)3(/sub) group than in controls (T(sub)3(/sub), 52.7 ± 12.6, control 304.2 ± 69.9 (p<0.05)).

In conclusion, T(sub)3(/sub) treatment from day 0-4 of postnatal life decreases UCP3 mRNA expression in porcine adipose tissue. This suggests a different regulation of UCP3 in pigs compared to rodents during the neonatal period.

This work was supported by a Clinical Endocrinology Trust Medical Undergraduate Grant.