G. Miszkiel et al., Concentrations of catecholamines, ascorbic acid, progesterone and oxytocinin the corpora lutea of cyclic and pregnant cattle, REPROD NUTR, 39(4), 1999, pp. 509-516
To determine if there are inter-relationships between progesterone, oxytoci
n (OT), dopamine (DA), noradrenaline (NA) and ascorbic acid, these compound
s were measured in the corpus luteum (CL) from cattle at different stages o
f the oestrous cycle (n = 42) and from 1-5 months of pregnancy (n = 27). Th
ey were measured by radioimmunoassay (RIA), high performance liquid chromat
ography (HPLC) and colorimetric methods. Corpora lutea were collected from
heifers and cows within 30 min of slaughter on days 1-5, 6-10, 11-16 and 17
-21 of the oestrous cycle. The stage of pregnancy was determined on the bas
is of foetal size and development. Each CL was divided into four parts and
stored in liquid nitrogen. For hormone estimation, the tissue was homogenis
ed/powdered and suspended in phosphate buffer (for OT and progesterone), 0.
1 M trichloracetic acid (TCA; for catecholamines) or in ice-cold metaphosph
oric acid (for ascorbic acid). There were no significant differences in the
measured parameters between cows and heifers, and so the data were combine
d. The concentration of DA was correlated with NA (r = 0.66; P < 0.001) dur
ing the oestrous cycle and was highest in newly formed CL (P < 0.01) as com
pared with early CL, regressed CL and CL of pregnant females. NA was negati
vely correlated (P < 0.01) with progesterone (r = -0.53) and OT (r = -0.41)
. In contrast, progesterone and OT were positively correlated with each oth
er (r = 0.81; P < 0.01) during all stages of the oestrous cycle, but not du
ring pregnancy. The lowest concentrations of ascorbic acid were observed in
regressed CL. Ascorbic acid concentrations were correlated (P < 0.01) with
those of progesterone (r = 0.68), OT (r = 0.42) and DA (r = -0.37). Luteal
concentrations of ascorbic acid, progesterone and OT followed a pattern co
nsistent with the development and regression of the CL. Luteal concentratio
ns of catecholamines were not consistent with this pattern. (C) Inra/Elsevi
er, Paris.