E. Bekeova et al., ALKALINE-PHOSPHATASE IN THE PUERPERIUM OF EWES AND ITS RELATION TO THYROID-HORMONES AND OVARIAN-STEROIDS, Veterinarni medicina, 38(6), 1993, pp. 359-368
Triacylglycerols as the sources of cholesterol, the primary precursor
of steroid synthesis, are one of the factors that limit the speed of s
teroidogenesis. Synthesis and resynthesis of triacylglycerols depend,
in addition to other factors, on phosphatid hydrolysis that is control
led during pregnancy by placentary ALP (S u m i k a w a et al., 1987)
and the FFA pool in the systemic blood stream. Enzymes participating i
n FFA release from the fat tissue are affected by thyroid hormones and
TSH (M a y e s , 1977). In view of the above facts, this work was aim
ed at the observation of changes in alkaline phosphatase (ALP), thyrox
ine (T4), triiodothyronine (T3),17 beta-oestradiol (E2) and progestero
ne (P4) levels and their mutual correlations in the systemic blood str
eam of sheep from the first day after parturition to day 51 p.p. Our a
ttention was paid to the possible delayed effects of placentary ALP an
d thyroid hormones on the synthesis of ovarian steroids in puerperal e
wes. 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 accordin
g to the Czechoslovak State Standard CSN 46 7070. Blood samples were t
aken from the v. jugularis from 8 to 9 o'clock a.m. 24 hs (day-1) prio
r to parturition (a.p.), 36 hs and on days 4, 7, 14, 17, 21, 2 5, 34,
42 and 51 after parturition (p.p). As compared with day-1 (2.6 +/- 1.0
8 mukat/l), ALP concentrations showed a decrease with minimum values o
ccurring on day 17 (1.34 +/- 0.97 mukat/l, P < 0,05). T4 concentration
s 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 stero
id hormones, E2 and P4, significantly decreased [from 2.45 +/- 0.65 an
d 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 a
nd 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. Slightly, in comparison with day-1, insignificantly
increased ALP concentrations were observed from day 17 to day 21; ins
ignificantly increased T4 and T3 levels were recorded from day 21 to d
ay 51. In T4 : ALP, a statistically significant correlation (P < 0.001
) was observed as late as on day 51 p.p. while in ALP : P4 and ALP : E
2, a statistically significant correlation (P < 0.05) was recorded on
days 17 and 42 p.p., respectively. The decrease in ALP levels observed
until day 17 p.p. coincides with the data reported by K a d l e c (19
90), who says that the decrease in ALP concentrations is related to th
e extinction of the foetoplacentary unit. A gradual increase in ALP le
vels could be induced by the gradual restoration of the hypothalamo-pi
tuitary ovarian axis and the activation of ovarian steroid synthesis (
B o o s et al., 1988; W i t k o w s k i et al., 1989). On the basis of
literary data and our present as well as previous results it can be c
oncluded that placentary ALP does not probably affect the dynamics of
ovarian steriods in spite of the fact that it persists in the systemic
blood stream during early puerperium. The significance of correlation
of the relation ALP: P4 on day 51 postpartum (P < 0.001) points to th
e mutual interconnection between thyroxine and ALP in this phase of re
productive cycle which can exert eventually a significant influence on
metabolism of lipids and subsequently also on ovarian steroids.