caa a22 4500 465803512 CHVBK 20180323112058.0 cr unu---uuuuu 170327e19900101xx s 000 0 eng 10.1007/BF03348585 doi (NATIONALLICENCE)springer-10.1007/BF03348585 Stimulation of liver mitochondrial α -glycerophosphate dehydrogenase activity by L-thyroxine in thyroidectomized rats: comparison with the suppression of pituitary TSH secretion [Elektronische Daten] [G. Costante, D. Crupi, R. Catalfamo, Francesco Trimarchi] The rate of liver mitochondrial α-glyce-rophosphate dehydrogenase (GPD) induction was compared to the suppression of pituitary thyrotropin (TSH) secretion in thyroidectomized rats submitted to prolonged administration of small amounts of L-thyroxine (T4). With both 350 and 530 ng T4/100 g bw/day, liver α-GPD activity remained at post-thyroidectomy level (mean ± SE: 0.030 ± 0.002 and 0.034 ± 0.001 Δ A/mg prot/ min, respectively) throughout all experiment. A sharp increase in enzyme activity was observed after 3 weeks of treatment in rats receiving 715 ng T4 / 100 g bw / day (mean ± SE: 0.086 ± 0.003 Δ A/mg prot/min). In contrast, serum TSH levels were lower than pretreatment values (199 ± 8ng/dl) in rats receiving 350 ng T4/100 g bw/day (mean ± SE: 104 ± 15 ng/dl; t = 7.48, p < 0.001), decreased progressively with increasing T4 doses (m ± SE:530 ng T4/100 g/day = 54 ± 5 ng/dl; 715 ng T4/100 g/day = 36 ± 7 ng/dl), after only 48 h of treatment and were not significantly modified thereafter. The data are in agreement with the hypothesis of a nonlinear relationship between the degree of thyroid hormone receptor occupancy and the rate of liver mitochondrial α-GPD induction. Italian Society of Endocrinology (SIE), 1990 L-thyroxine nationallicence thyroid hormone effect nationallicence liver mitochondrial a-GPD nationallicence TSH nationallicence thyroidectomized rats nationallicence Costante G. Istituto Pluridisciplinare di Clinica Medica e Terapia Medica Generale e Speciale, Università di Messina, 98125, Messina, Italy aut Crupi D. Istituto Pluridisciplinare di Clinica Medica e Terapia Medica Generale e Speciale, Università di Messina, 98125, Messina, Italy aut Catalfamo R. Istituto Pluridisciplinare di Clinica Medica e Terapia Medica Generale e Speciale, Università di Messina, 98125, Messina, Italy aut Trimarchi Francesco Istituto Pluridisciplinare di Clinica Medica e Terapia Medica Generale e Speciale, Università di Messina, 98125, Messina, Italy aut Journal of Endocrinological Investigation Springer International Publishing 13/1(1990-01-01), 61-64 0391-4097 13:1<61 1990 13 40618 https://doi.org/10.1007/BF03348585 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF03348585 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Costante G. Istituto Pluridisciplinare di Clinica Medica e Terapia Medica Generale e Speciale, Università di Messina, 98125, Messina, Italy aut NATIONALLICENCE 700 1- Crupi D. Istituto Pluridisciplinare di Clinica Medica e Terapia Medica Generale e Speciale, Università di Messina, 98125, Messina, Italy aut NATIONALLICENCE 700 1- Catalfamo R. Istituto Pluridisciplinare di Clinica Medica e Terapia Medica Generale e Speciale, Università di Messina, 98125, Messina, Italy aut NATIONALLICENCE 700 1- Trimarchi Francesco Istituto Pluridisciplinare di Clinica Medica e Terapia Medica Generale e Speciale, Università di Messina, 98125, Messina, Italy aut NATIONALLICENCE 773 0- Journal of Endocrinological Investigation Springer International Publishing 13/1(1990-01-01), 61-64 0391-4097 13:1<61 1990 13 40618 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer