Plasma Progesterone Concentrations during Pregnancy and Lactation in Mongolian gerbils(Meriones unguiculatus).

Abstract

Plasma progesterone (P4) concentrations during pregnancy and lactation in Mongolian gerbils were measured by enzymeimmunoassay (EIA). The P4 concentration was found to increase rapidly after mating and reach a peak on day 6 of pregnancy. The maximum level (166.0 to 184.8 ng/ml) was maintained to day 12 and then decreased to a plateau at a moderate level until day 21. The P4 concentration declined to its lowest level on day 24 of pregnancy, one day before parturition. The P4 concentration on the first day of lactation was similar to that on the last day of pregnancy. The concentration then increased to a significantly higher level on day 4 of lactation, remained relatively stable until day 19, and then significantly dropped on day 22. The present study in gerbils showed that the plasma P4 concentration during pregnancy was higher in the first half than in the second half of gestation and that the P4 level during lactation was fairly constant. The pattern of changes in the P4 level during pregnancy and lactation is therefore quite different from that of other rodent species, such as rats, mice and hamsters.

Variations of Serum Estradiol and Progesterone Levels during Consecutive Reproductive States in Mongolian Gerbils (Meriones unguiculatus)

“…In the present study, the pattern of P4 levels during gestation was similar to those observed in previous works [11,12], but differed from those detected in rats and mice. In rats and mice, P4 levels during the first half of gestation are lower than the levels during the second half of gestation [2,3,9,20].…”

“…Because of the special characteristics of the Mongolian gerbil, it has become an extensively used experimental animal, for example, in neuroscience, physiology, pharmacological, parasitological, and endocrinological research [21]. The estrous cycle of the Mongolian gerbil is 4 to 7 days, pregnancy is 24 to 26 days, lactation is 21 to 22 days, and the litter size at birth ranges from 1 to 9 offspring [11,12,18,22]. We can further understand the reproductive characteristics of Mongolian gerbils through studies -Original-of reproductive hormones.…”

“…We can further understand the reproductive characteristics of Mongolian gerbils through studies -Original-of reproductive hormones. However, there are only a few reports on the secretion patterns of reproductive hormones during different reproductive states in Mongolian gerbils [6,11,12,22,24]. The aims of this study were, first, to confirm the variations of serum estradiol (E2) and progesterone (P4) levels in different reproductive states of Mongolian gerbils and to analyze the differences of E2 and P4 patterns between Mongolian gerbils and other rodents such as rats and mice; second, to analyze the differences in variations of E2 and P4 levels in primiparous and multiparous gerbils; and third, to analyze the relationships between the two hormone levels and the reproductive states of Mongolian gerbils.…”

The Effects of Quinestrol as a Contraceptive in Mongolian Gerbils (Meriones unguiculatus)

“…Changing patterns of E2 and P4 levels are correlated with the reproductive stages of Mongolian gerbils [21]. A higher P4 level during the first half of gestation is important for successful pregnancy in Mongolian gerbils [15,21]. However, the P4 levels during the first half of gestation in quinestrol-treated Mongolian gerbils were lower than those in the control group.…”

Variations in Serum Gonadotropin and Prolactin Levels during Consecutive Reproductive States in Mongolian Gerbils (Meriones unguiculatus)

“…We have previously reported the changes in the levels of estradiol and progesterone during the different reproductive states in Mongolian gerbils [15]. However, data on the secretion patterns of reproductive hormones in Mongolian gerbils during different reproductive states remain insufficient [4,9,10,25,27]. To our knowledge, this is the first study of the secretion patterns of gonadotropin and prolactin during consecutive reproductive states in Mongolian gerbils, and it therefore contributes to a detailed understanding of their reproductive physiology.…”