Details

Autor(en) / Beteiligte

• Coleoni, A H
• Cherubini, O

Titel

Sex-related differences in the activity of liver mitochondrial alpha-glycerophosphate dehydrogenase in the rat

Ist Teil von

• Acta physiologica et pharmacologica latinoamericana : organo de la Asociacion Latinoamericana de Ciencias Fisiologicas y de la Asociacion Latinoamericana de Farmacologia, 1989, Vol.39 (3), p.245

Ort / Verlag

Argentina

Erscheinungsjahr

1989

Quelle

MEDLINE

Beschreibungen/Notizen

• The rat liver mitochondrial alpha-glycerophosphate dehydrogenase (alpha-GPD) is an enzyme that markedly responds to thyroid hormone administration. Its activity is considered a good index of thyroid status in peripheral tissues. In this study alpha-GPD activity and the binding characteristics of nuclear T3 receptors (maximal binding capacity, MBC, and affinity constant, Ka) were compared in male and female rats. Basal alpha-GPD activity in adult females was significantly higher than in the age-matched males. The same difference was observed in immature animals. The cyclic physiological variations in the ovarian steroid hormones during the estrous cycle did not significantly affect alpha-GPD activity, MBC or Ka. Orchiectomy or replacement doses of testosterone administered to orchiectomized rats, had no effect on alpha-GPD activity compared to sham-operated normal males. In females, neither oophorectomy nor testosterone injection to oophorectomized animals induced changes in the enzyme activity. Liver nuclear T3-content, MBC and Ka revealed no systematic differences in both sexes. The T3-induced alpha-GPD activity after a single large dose of T3 designed to fully saturate the nuclear sites for a 24 h period, was significantly higher in female compared to male rats. The kinetics of alpha-GPD showed an identical Km in both sexes, while Vmax was significantly higher in the females. The data suggest that the factors leading to the different activity of alpha-GPD in both sexes, although unknown, may be not related to the sex-hormone differences.