[Alkaline phosphatase during the puerperium in ewes and its relation to thyroid hormones and ovarian steroids].

Triacylglycerols as the sources of cholesterol, the primary precursor of steroid synthesis, are one of the factors that limit the speed of steroidogenesis. Synthesis and resynthesis of triacylglycerols depend, in addition to other factors, on phosphatid hydrolysis that is controlled during pregnancy by placentary ALP (Sumikawa et al., 1987) and the FFA pool in the systemic blood stream. Enzymes participating in FFA release from the fat tissue are affected by thyroid hormones and TSH (Mayes, 1977). In view of the above facts, this work was aimed at the observation of changes in alkaline phosphatase (ALP), thyroxine (T4), triiodothyronine (T3), 17 beta-oestradiol (E2) and progesterone (P4) levels and their mutual correlations in the systemic blood stream of sheep from the first day after parturition to day 51 p.p. Our attention was paid to the possible delayed effects of placentary ALP and thyroid hormones on the synthesis of ovarian steroids in puerperal ewes. Nine merino sheep were included in the experiment; they lambed in the first decade of February and were kept together with their lambs in a classical sheep-cot on deep litter. The animals were fed according to the Czechoslovak State Standard CSN 46 7070. Blood samples were taken from the v. jugularis from 8 to 9 o'clock a.m. 24 hs (day -1) prior to parturition (a.p.), 36 hs and on days 4, 7, 14, 17, 21, 25, 34, 42 and 51 after parturition (p.p.). As compared with day -1 (2.6 +/- 1.08 mu kat/l), ALP concentrations showed a decrease with minimum values occurring on day 17 (1.34 +/- 0.97 mu kat/l, P < 0.05). T4 concentrations also decreased from day -1 (59.4 +/- 9.69 nmol/l) to day 21 (54.89 +/- 11.06 nmol/l, P < 0.05). A similar decrease (from 1.82 +/- 0.33 nmol/l on day 1 to 0.85 +/- 0.32 nmol/l on day 21) could also be observed in T3 levels. As early as 36 hs p.p., the concentrations of both steroid hormones, E2 and P4, significantly decreased [from 2.45 +/- 0.65 and 9.46 +/- 0.34 nmol/l on day -1 to 0.30 +/- 0.24 and 0.05 +/- 0.08 nmol/l, respectively (P < 0.001)]. Throughout the period of investigation, apart from an unsubstantial increase in E2 values on days 17 and 42 and an episodic increase in P4 levels on day 34, the concentrations of both steroids had the values that were significantly lower than those observed on day -1.(ABSTRACT TRUNCATED AT 400 WORDS)