Effect Of Oestrous Cycle Research Articles

Panic-like responses of female Wistar rats confronted by Bothrops alternatus pit vipers, or exposure to acute hypoxia: Effect of oestrous cycle.

Anxiety-related diseases are more than twice as common in women than in men, and in women, symptoms may be exacerbated during the late luteal phase of the menstrual cycle. Despite this, most research into the underlying mechanisms, which drives drug development, have been carried out using male animals. In an effort to redress this imbalance, we compared responses of male and female Wistar rats during exposure to two unconditioned threatening stimuli that evoke panic-related defensive behaviours: confrontation with a predator (Bothrops alternatus) and acute exposure to hypoxia (7% O2 ). Threatened by venomous snake, male and female rats initially displayed defensive attention, risk assessment, and cautious interaction with the snake, progressing to defensive immobility to overt escape. Both males and females displayed higher levels of risk assessment but less interaction with the predator. They also spent more time in the burrow, displaying inhibitory avoidance, and more time engaged in defensive attention, and non-oriented escape behaviour. In females, anxiety-like behaviour was most pronounced in the oestrous and proestrus phases whereas panic-like behaviour was more pronounced during the dioestrus phase, particularly during late dioestrus. Acute hypoxia evoked panic-like behaviour (undirected jumping) in both sexes, but in females, responsiveness in late dioestrus was significantly greater than at other stages of the cycle. The results reveal that females respond in a qualitatively similar manner to males during exposure to naturally occurring threatening stimuli, but the responses of females is oestrous cycle dependent with a significant exacerbation of panic-like behaviour in the late dioestrus phase.

Effect of oestrous cycle on serum electrolytes and liver enzymes in Red Sokoto goats

This study was carried out to determine changes in serum electrolytes and liver enzymes during the oestrous cycle in Red Sokoto goats. Eleven (11) apparently healthy Red Sokoto goats were synchronized with a single injection of 7.5 mg of PGF2α. The goats were bled via jugular venipuncture in oestrus or late oestrus, metoestrus/early dioestrus, mid-dioestrus and late dioestrus/proestrus. Mean serum sodium, potassium and chloride levels non-significantly fluctuated during the oestrous cycle. Calcium levels in oestrus or late oestrus were higher (P < 0.05) than in late diestrus/pro-oestrus. There was a positive correlation between oestradiol and calcium concentrations (r = 0.771; P < 0.05). Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) concentrations non-significantly fluctuated during the oestrous cycle. Progesterone and AST concentrations were correlated (r = 0.925; P < 0.05) during the oestrous cycle. In conclusion, some serum electrolytes and liver enzymes fluctuated and correlated with ovarian steroids in different phases of the oestrous cycle. The information generated may be useful as physiologic reference values for reproductive herd health management. Key words: Red Sokoto goats, oestrous cycle, electrolytes, liver enzymes.

Dynamic proteome signatures in gametes, embryos and their maternal environment

Comprehensive molecular analysis at the level of proteins represents a technically demanding, but indispensable, task since several post-transcriptional regulation mechanisms disable a valid prediction of quantitative protein expression profiles from transcriptome analysis. In crucial steps of gamete and early embryo development, de novo transcription is silenced, meaning that almost all macromolecular events take place at the level of proteins. In this review, we describe selected examples of dynamic proteome signatures addressing capacitation of spermatozoa, in vitro maturation of oocytes, effect of oestrous cycle on oviduct epithelial cells and embryo-induced alterations to the maternal environment. We also present details of the experimental strategies applied and the experiments performed to verify quantitative proteomic data. Far from being comprehensive, examples were selected to cover several mammalian species as well as the most powerful proteomic techniques currently applied. To enable non-experts in the field of proteomics to appraise published proteomic data, our examples are preceded by a customised description of quantitative proteomic methods, covering 2D difference gel electrophoresis (2D-DIGE), nano-liquid chromatography combined with tandem mass spectrometry, and label-free as well as stable-isotope labelling strategies for mass spectrometry-based quantifications.

Effect of Oestrous Cycle on the Oxidative Burst Activity of Blood Polymorphonuclear Leucocytes in Cows

Blood polymorphonuclear leucocyte (PMN) oxidative burst activity, plasma cortisol levels, and the total and differential white blood cells counts (WBC) of six cycled dairy cows were evaluated for a period of 24 days, three times a week; on Mondays, Wednesdays and Fridays. The PMN oxidative burst was indirectly evaluated by flow cytometry, measuring the intracellular oxidation of 2',7'-dichlorofluorescein diacetate to 2',7' dichlorofluorescein (DCF) by H2O2-production. Results are presented as the mean fluorescence intensity (MFI) of DCF. Cow's oestrous cycle was evaluated by following the plasma progesterone levels using a radioimmunoassay method. Levels of cortisol in the plasma were measured using a fluorimetric method. The oxidative burst activity of PMN, represented a maximum value (MFI=117.6+/-7.4) during the oestrous period. A fall was then observed, in which a steady state was observed during the lutheinic phase of the oestrous cycle, reaching the minimum value [MFI=73.2+/-11.2 (p<or=0.01)] on the days +8, +9 and +10. No significant variations were observed in the levels of cortisol, or in total and differential WBC, during the whole period. Nevertheless, as far as cortisol levels were concerned, a trend analogous to that of the oxidative burst activity was observed. Our results demonstrated that the oestrous cycle might influence directly, or indirectly, the immune system of cows, by altering the oxidative burst of PMN.

Effect of oestrous cycle and early pregnancy on uterine production and expression of immune regulatory factors in gilts

This study was undertaken to characterize uterine immune factors involved in the establishment of pregnancy in gilts. Thirty crossbred Yorkshire–Landrace gilts of similar age and weight were observed twice a day for oestrous behaviour with intact boars. On the day of first standing oestrus (Day 0) and 12 h later, 15 gilts were inseminated with pooled semen from Duroc boars of proven fertility. Pregnant gilts were slaughtered either on Days 10, 15 or 25 of gestation ( n=5 per day). The other 15 gilts were not inseminated and were slaughtered on either Days 0, 10 or 15 of the oestrous cycle ( n=5 per day). Immediately after slaughter, endometrial tissue samples from the mesometrial side were removed for gene expression using RNase protection assay and in situ hybridization methodologies. The other uterine horn was flushed with 20 ml of PBS to collect the uterine fluid. In pregnant gilts, endometrial interleukin (IL)-6 mRNA expression was higher on Day 15 than on Days 10 and 25 ( P<0.01 and P<0.1, respectively). On Day 15, IL-6 expression was also significantly higher ( P<0.01) in pregnant gilts than in cyclic gilts. In both pregnant and cyclic gilts, transforming growth factor (TGF)-β2 in uterine fluid was significantly higher ( P<0.0001) on Day 15 than on Day 10. At the gene expression level, TGF-β2 also increased between Days 10 and 15 in both cyclic and pregnant gilts but differences were not significant. On Day 15, concentrations of interferon-γ and prostaglandin E 2 (PGE 2) in uterine fluid were markedly higher ( P<0.001) in pregnant gilts than in cyclic gilts, whereas the total amount of TGF-β2 in uterine fluid and its endometrial expression were approximately 70% higher although this increase was not significant. Finally, tumour-necrosis factor-α and granulocyte-macrophage/colony-stimulating factor mRNA expressions were undetectable in all endometrial samples. In conclusion, production and/or expression of uterine TGF-β2, IL-6 and PGE 2 increased during the embryonic attachment period and are coincidental with embryonic interferon-γ production.

Effects of estrus cycle, ovariectomy, and treatment with estrogen, tamoxifen, and progesterone on apolipoprotein(a) gene expression in transgenic mice.

Plasma levels of lipoprotein(a) (Lp(a)), are regulated by the synthetic rate of apolipoprotein(a) (apo(a)), a major protein component of this atherogenic lipoprotein. Exogenously administered sex steroid hormones are potent regulators of plasma Lp(a) concentrations. We utilized a recently developed apo(a) yeast artificial chromosome (YAC) transgenic mouse model to study the effects of ovariectomy, estrus cycle, and exogenous administration of ethinyl-estradiol, the partial estrogen receptor agonist, tamoxifen, and progesterone on circulating apo(a) plasma levels. Analysis of liver RNA revealed that estrogen and tamoxifen exerts their plasma apo(a) lowering effect at the level of apo(a) mRNA. This action of estrogen and tamoxifen may contribute to their antiatherosclerotic and cardiovascular protective effect.

Effects of estrus cycle on thermoregulatory responses during exercise in rats

In female rats, rectal temperature (Tre), tail vasomotor response, oxygen uptake (VO2), and carbon dioxide production (VCO2) were measured in proestrus and estrus stages during treadmill running at two different speeds at an ambient temperature (Ta) of 24 degrees C. Experiments were performed at 2.00-6.00 a.m., when the difference in Tre was greatest between the two stages; Tre at rest in the estrus stage was 0.54 degrees C higher than in the proestrus stage. In a mild warm environment, threshold Tre for a rise in tail skin temperature (Ttail) was also higher in the estrus stage than in the proestrus stage. In contrast, no difference was seen in the threshold Tre and steady state Tre at the end of exercise between proestrus and estrus stages. These values were higher at the higher work intensity. VO2 was also similar between the two stages, except in the second 5 min after the beginning of exercise, when VO2 was greater and Tre rose more steeply in the proestrus stage. These data indicate that deep body temperature during exercise is regulated at a certain level depending on the work intensity and is not influenced by the estrus cycle.

Prostanoid synthesis by isolated rat glomeruli: effect of oestrous cycle and pregnancy.

1. An increase in glomerular prostaglandin (PG) synthesis has been reported in two experimental models of increased glomerular filtration rate (GFR). 2. Because pregnancy, in women and rats, is also associated with an increased GFR, we studied PG biosynthesis by glomeruli isolated from pregnant rats in comparison with virgin rats at the different phases of the oestrous cycle. 3. PGE2 and PGF2 alpha synthesis markedly increased during pregnancy (at day 21 of gestation a five- to sevenfold increase of PGE2 and PGF2 alpha was seen; at day 15 of gestation a threefold increase of PGE2 and a sixfold increase of PGF2 alpha was noted). However, thromboxane A2 (TXA2) synthesis was similar in all the groups studied. 4. Among the four phases of the oestrous cycle, dioestrus was characterized by a significant increase in glomerular synthesis of PGE2. 5. The fact that during pregnancy the increase in the vasodilator PGE2 is not counteracted by an increase in the constrictor TXA2 must be taken into account when explaining the glomerular hyperfiltration which characterizes the pregnant state. 6. The increase of PGE2 synthesis during dioestrus should be considered in studies of PG synthesis using virgin rats as controls.

The effects of estrus cycle on drug metabolism in the rat.

The effect of the female rat estral cycle on microsomal drug metabolism in-vivo and in-vitro has been studied. Two microsomal enzymes, aminopyrine-N-demethylase and aniline hydroxylase showed a greater specific activity (p less than 0.01) in the diestrus phase of the estral cycle while the oxidative enzyme aryl hydrocarbon hydroxylase and the conjugative enzyme, glucuronyl transferase, were not affected. In vivo studies which included theophylline and antipyrine metabolism, and hexobarbital sleeping times showed no difference between the different phases of the estral cycle. Conflicting evidence about the effect of steroid sex hormones on hepatic drug metabolism is discussed.