Glucose modulation of alterations in serum iodothyronine concentrations induced by fasting

Effects of food restriction on cortisol, TSH and iodothyronine concentrations in the plasma of the newborn lamb

“…In agreement with previous work (Bassett and Thorburn, 1969 ;Paisey and Nathanielsz, 1971 ;Nathanielsz et al, 1972) (Vinik et al, 1975 ;Carlson et al, 1977 ;Burman et al, 1979Burman et al, , 1980Burman et al, , 1983R6jdmark and Nygren, 1983), but such data are not available in sheep. Therefore, although plasma total and free T4 levels rose during the first 8 h of life in control lambs, they did not change in restricted animals.…”

“…The particular sensitivity of T3 suggests that food restriction does not only affect thyroid secretion. A reduction of peripheral conversion of T4 to T3 has been reported in rats (Balsam and Ingbar, 1979 ;Chopra, 1980 ;Gavin et al, 1980 ;Balsam et al, 1981a, b ;Gavin and Moeller, 1983 ;Shank et al, 1984 (Suda et al, 1978 ;Hughes et al, 1984) and obese (Burman et al, 1979(Burman et al, , 1980Jaedig and Faber, 1982 ;Marugo et al, 1984) men and in sheep (Blum et al, 1980). However, during fasting reverse T3 levels dot not change (Blum and Kunz, 1981) or decrease (Tveit and Almlid, 1980) in calves.…”

“…The drop in plasma T3 levels was even more important : the value recorded at 16 h post partum was as low as 25 % of that observed in suckling animals. These results are comparable with those obtained during a fasting period of 30 h to 10 days : in cattle, sheep and rats, plasma T4 and T3 levels decreased significantly (Blum et al, 1980 ;Tveit and Almlid, 1980 ;Blum and Kunz, 1981 ;Tveit and Larsen, 1983 ;Burger et al, 1981 ; Moeller, 1983) ; in normal or obese men, only T3 was affected (Suda etal., 1978 ;Burman et al, 1979Burman et al, , 1980Burman et al, , 1983Marugo et al, 1984). The particular sensitivity of T3 suggests that food restriction does not only affect thyroid secretion.…”

Neonatal levels of plasma thyroxine in male and female calves fed a colostrum or immunoglobulin diet or fasted for the first 28 hours of life

“…An increase was noted in humans (Azizi, 1978 ;Burman et al, 1979 ;Suda et al, 1978), birds (May, 1978 ;Almeida and Thomas, 1981) and rabbits (Takagi et al 1978), but rats (Chopra, 1980 ;Hastings and Zeman, 1979 ;Heinen et al, 1981), piglets (Slebodzinski et al, 1982) and ruminants (Bahnak et al, 1981 ;Blum et a/., 1980 ;Tveit and Almlid, 1980) show a decrease.…”

“…This may be because not enough samples were studied or that they were not collected at the exact postpartum time when the transient rise occurred. On the contrary, the frequent and precise sampling practiced by Davicco et al (1982) (Balsam and Ingbar, 1979 ;Kaplan and Utiger, 1978 ;Naito et al, 1981) and piglets (Slebodzinski et al, 1982), has been shown to result in a decrease of circulating T3 in these species (Chopra, 1980 ;Hastings and Zeman, 1979 ;Heinen et al, 1981 andSlebodzinski et al, 1982, respectively) ; this phenomenon has also been shown in humans (Azizi, 1978 ;Burman et al, 1979 ;Suda et al, 1978), adult sheep (Blum et al, 1980), growing bulls Tveit and Almlid, 1980), deer (Bahnak et al, 1981), chickens (May, 1978) …”