Dexamethasone is widely used in both veterinary and human medical practices. However, it seems to cause some deleterious effects on pregnancy probably by causing changes in the reproductive hormone levels and their corresponding receptor concentrations. This study investigated the effects of dexamethasone on these parameters. Twenty healthy adult Yankasa sheep comprising 18 ewes and 2 rams were used for this study. Pregnancies were achieved by natural mating after estrus synchronization. Dexamethasone was administered at 0.25 mg/kg body weight on days 1, 3, and 5 during first trimester; days 51, 53, and 55 during second trimester; and days 101, 103, and 105 during the third trimester. Blood samples were collected biweekly for hormonal assay. Uterine biopsies were harvested through caesarean section for immunohistochemical analysis. Results showed that dexamethasone significantly (p < 0.05) decreased progesterone concentrations and caused abortion in Yankasa sheep but had no significant (p > 0.05) effect on estrogen, while progesterone receptors (PR) were upregulated. The abortion could probably be due to decreased progesterone concentrations as a consequence of the adverse effects on placenta. The PR upregulation may be a compensatory mechanism to increase progesterone sensitivity. It was concluded that dexamethasone should not be used in advanced pregnancy in Yankasa sheep.
The study aims to present baseline data on the reproductive anatomy of a poorly known tropical deer species, Rusa deer (Rusa timorensis). The anatomy of female reproductive system is described using seven uniparous hinds, aged between four and eight years. The various reproductive structures were studied via s t a n d a r d d e s c r i p t i v e methods. There was a significant difference in the length and width of both right and left ovaries. The left ovary was slightly larger than the right ovary which indicates that it is physiologically more active. The results of the study showed that the anatomy of female reproductive system of R. timorensis was similar to that observed in domestic ruminants except that the uterus did not have an interconual ligament and this implies that the uterine horns are anchored in such a way that sperm deposited into only one uterine horn of the Rusa deer will be transported to the other uterine horn (interconual transport). Unlike the red brocket deer and pampas deer, the cervix of R. timorensis was characterized by six cervical rings projecting into the cervical canal. This feature should be taken into account when designing effective instrumentation and techniques for transcervical passage of semen during artificial insemination in this species. The results from this study have provided baseline data on the reproductive anatomy of this vulnerable species, and the knowledge generated can be useful in the development of appropriate reproductive techniques in order to increase its population in captivity and also enable easy detection of its reproductive anomalies, thus strategies to propagate and conserve the species can be established.
BackgroundDespite the widespread use of dexamethasone in veterinary and human medicine, it is reported to cause some severe pregnancy related side effects like abortion in some animals. The mechanism of the response is not clear but seems to be related to interspecies and/or breed difference in response which may involve alterations in the concentrations of some reproductive hormones.MethodsTwenty Sahel goats comprising 18 does and 2 bucks were used for this study. Pregnancies were achieved by natural mating after synchronization. Repeated dexamethasone injections were given at 0.25 mg/kg body weight. Blood samples were collected biweekly for hormonal assay. Uterine biopsies were harvested at days 28 and day 78 of gestation through caesarean section for immunohistochemical analysis using 3 pregnant does randomly selected from each group at each instant. Data were expressed as Means ± Standard Deviations and analyzed using statistical soft ware package, GraphPad Instant, version 3.0 (2003) and progesterone receptor (PR) were scored semi-quantitatively.ResultsDexamethasone treatments had no significant (p > 0.05) effect on progesterone and estrogen concentrations in pregnant Sahel goats but up regulated PR from 2+ to 3+ in second trimester.ConclusionAs dexamethasone adverse effect on placenta is an established fact, the lack of effect on progesterone level in this study may be due to the fact that unlike other species whose progesterone production during pregnancy is placenta – dependent, in goats is corpus luteum - dependent. Consequently dexamethasone adverse effect on placenta reported in literatures did not influence progesterone levels during pregnancy in Sahel goat. The up regulation of progesterone receptor (PR) in Sahel goat gravid uterus is a beneficial effects and that dexamethasone can safely be used in corpus luteum – dependent progesterone secreting pregnant animal species like Sahel goat and camel. Therefore source of progesterone secretions during pregnancy should be considered in clinical application of dexamethasone in pregnancy.
A typical mammalian erythrocyte fragility phenotype (EFP) exhibits a sigmoidal curve of the dependence of fragilities (% haemolysis) on hypotonic saline concentrations, but the goat EFP tends to be hyperbolic. Physiological variation in median erythrocyte fragility (MEF) and the associated EFP of Sahel goats was investigated. Erythrocyte osmotic fragility (EOF) was determined in hypotonic saline using heparinized venous blood from 47 goats (23 males and 24 non-pregnant dry females) aged 1-4 years and weighing 18.87 ± 6.32 (9-30) kg. Packed cell volume (PCV), erythrocyte count and mean corpuscular volume (MCV) were also estimated. Low, medium and high EFP were based on MEF of < 7, 7-8 and > 8 g/L, respectively. MEF of all the goats was 7.5 ± 0.6 (5.9-8.4) g/L. Phenotypic drift from sigmoidal to hyperbolic EOF curve was observed at the lower and upper limits of the phenotypic variation. Frequencies of occurrence of low, medium and high EFP were not different (p > 0.05) between males and females. Fragiligrams of low, medium and high EFP separated at erythrocyte fragilities of 10-70% and saline tonicity of 7-8 g/L. The saline concentrations causing fragilities of 10-70% differed (p < 0.05) among the phenotypes. There was no correlation (r = -0.28, -0.30; p > 0.05) between MEF and MCV or PCV, and between PCV and MCV. In conclusion, phenotypic drift in EOF occurred in Sahel goats without influence by erythrocyte parameters and represented the physiological variability of EOF endpoint estimates that would serve as reference limits in evaluation of erythrocyte membrane defects.
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