Influence Of Reproductive State Research Articles

Influence of reproductive state and temperature on the functional response of the marbled crayfish, Procambarus virginalis

Influence of reproductive state and temperature on the functional response of the marbled crayfish, Procambarus virginalis

Changes in some hematobiochemical and hormonal profile in Barki sheep with various reproductive statuses

The current work aimed to test the fit hypothesis; does the animal reproductive status have an impact on the hormonal milieu of the animals and consequently its body metabolic status? In this study, we assessed the changes in circulating hormones, key metabolites and blood parameters taking place during different stages of the estrous cycle and pregnancy in Egyptian Barki ewes. An ultrasonographic examination as well as blood sampling were conducted, before the morning feeding, on clinically healthy cyclic non-pregnant (n=7) and pregnant (n=9) Barki ewes at early- (d 60±5 post breeding [PB]), mid- (d 90±5 PB) and late- (d 135±5 PB) stage of pregnancy. The results showed marked changes in certain biochemical parameters of sheep blood serum during pregnancy as compared to luteal and/or follicular stages. Pregnancy was associated with significant higher levels of progesterone, glutathione peroxidase, malondialdehyde, nitric oxide and HDL. Samples from cyclic animals showed higher levels of insulin, T3, T4, superoxide dismutase and glucose. Nevertheless, leptin, triglycerides, cholesterol, VLDL, LDL and blood parameters did not vary between pregnant and non-pregnant animals. From these results we can conclude that the reproductive state influence on reproductive (progesterone) and metabolic (T3, T4 and insulin) hormonal levels, lipid peroxidation and body metabolism, which could have long-lasting consequences and therefore should be taken into consideration during the early prediction and/or diagnosis of metabolic diseases related to disturbance in energy balance and/or oxidative stress in Barki ewes.

Measuring stress responses in female Geoffroy's spider monkeys: Validation and the influence of reproductive state.

Fecal glucocorticoid metabolites are increasingly used to investigate physiological stress. However, it is crucial for researchers to simultaneously investigate the effects of reproductive state because estradiol and placental hormones can affect circulating glucocorticoid concentrations. Reports on the relationships between glucocorticoids and reproductive state are inconsistent among females. Unlike several primate species that have heightened glucocorticoid activity during lactation, humans experience reduced glucocorticoid activity during lactation. Rather than a taxonomic difference, we hypothesize that this is a result of different environmental stressors, particularly the threat of infanticide. Here, we expand the number of wild primate species tested by validating a glucocorticoid assay for female Geoffroy's spider monkeys. We investigate the effects of reproductive state on their glucocorticoid concentrations. Utilizing a routine veterinary exam on a captive population, we determined that fecal glucocorticoid metabolites increase in response to a stressor (anesthesia), and this rise is detected approximately 24 hr later. Additionally, we found that extracted hormone patterns in a wild population reflected basic reproductive biology-estradiol concentrations were higher in cycling than lactating females, and in lactating females with older offspring who were presumably resuming their cycle. However, we found that estradiol and glucocorticoid concentrations were significantly correlated in lactating but not cycling females. Similarly, we found that reproductive state and estradiol concentration, but not stage of lactation, predicted glucocorticoid concentrations. Unlike patterns in several other primate species that face a relatively strong threat of infanticide, lactating spider monkeys experience reduced glucocorticoid activity, possibly due to attenuating effects of oxytocin and lower male-initiated aggression than directed at cycling females. More broadly, we conclude that future studies using fecal glucocorticoid metabolites to index stress should consider that reproductive state might confound glucocorticoid measurements. Am. J. Primatol. 77:925-935, 2015. © 2015 Wiley Periodicals, Inc.

The influence of reproductive state on the agonistic interactions between male and female crayfish (Orconectes rusticus)

[Research analyzing social dynamics has shown that systems can be structured by individuals of different age, size, sex and reproductive state within a population. Extensive research on male–male interactions in crayfish has illustrated the mechanisms that underlie the agonism and social relationships that develop between conspecifics. Despite the wealth of knowledge on male–male interactions, there is a lack of knowledge on the role that reproductive state plays in modulating aggression between the sexes in crayfish. The purpose of this study was to investigate aggression between crayfish of different sexes and reproductive forms. Form I and II male crayfish were paired against glair and non-glair female crayfish in agonistic bouts. Fight outcomes, intensities and mating events were calculated from the paired interactions. Form I male crayfish won significantly more bouts with females than form II males. In addition, reproductive females won more bouts than non-reproductive males. Thus, reproductive state of the individual has a significant influence over the outcome and level of aggression within agonistic encounters. This finding may indicate that the individuals are approaching interactions with motivational states (reproductive needs versus resource acquisition)., Research analyzing social dynamics has shown that systems can be structured by individuals of different age, size, sex and reproductive state within a population. Extensive research on male–male interactions in crayfish has illustrated the mechanisms that underlie the agonism and social relationships that develop between conspecifics. Despite the wealth of knowledge on male–male interactions, there is a lack of knowledge on the role that reproductive state plays in modulating aggression between the sexes in crayfish. The purpose of this study was to investigate aggression between crayfish of different sexes and reproductive forms. Form I and II male crayfish were paired against glair and non-glair female crayfish in agonistic bouts. Fight outcomes, intensities and mating events were calculated from the paired interactions. Form I male crayfish won significantly more bouts with females than form II males. In addition, reproductive females won more bouts than non-reproductive males. Thus, reproductive state of the individual has a significant influence over the outcome and level of aggression within agonistic encounters. This finding may indicate that the individuals are approaching interactions with motivational states (reproductive needs versus resource acquisition).]

Changes in caridac output and hemolymph flow during hypoxic exposure in the gravid grass shrimp, Palaemonetes pugio

The cardiovascular response of decapod crustaceans to hypoxic exposure is well documented; however, information is limited concerning the influence of reproductive state on cardiovascular demands during hypoxic exposure. Given the additional metabolic demand of reproduction, we investigated the cardiovascular adjustments employed by gravid grass shrimp Palaemonetes pugio to maintain oxygen delivery during hypoxic stress. Cardiac output values were elevated in gravid compared to nongravid grass shrimp. Gravid grass shrimp were exposed to hypoxia and the stroke volume, heart rate, cardiac output and hemolymph flow were determined using video-microscopy and dimensional analysis. Oxygen consumption rates were determined using respirometry. There where no changes in the cardiac output values of gravid females until reaching 6.8 kPa O2, with a significant redistribution of hemolymph flow at 13.7 kPa O2. Flow was significantly decreased to the anterior lateral arteries that supply the ovaries and hepatopancreas, the anterior aorta and the posterior aorta. The redistribution of hemolymph flow away from these vessels results in an enhanced hemolymph flow to the sternal artery that supplies the ventral segmental system, the gills, the buccal apparatus and the ventral nerve cord. The data suggest that during hypoxic stress, gravid females place a priority on survival.

ACTH-induced stress response during pregnancy in a viviparous gecko: no observed effect on offspring quality

The typical stress response in reptiles involves the release of corticosterone from the adrenal glands. Elevated maternal concentrations of corticosterone in mammals during pregnancy may have deleterious effects on offspring fitness, and recent work has shown a suppression of the hormonal response to stress during pregnancy in rats. Little is known about the influence of reproductive state on the secretion of corticosterone in viviparous reptiles or on the effects of high levels of corticosterone during reproduction on the developing embryos. We examined whether New Zealand common geckos (Hoplodactylus maculatus), pregnant with embryos at stages 34-35 of development, secrete corticosterone in response to adrenocorticotrophic hormone (ACTH) and whether an ACTH-induced increase in maternal corticosterone affects the outcome of pregnancy. Corticosterone concentrations in pregnant lizards increased more than seven-fold over basal levels following injection of ACTH. However, there were no significant effects of elevated corticosterone on the duration or success of pregnancy, or on various morphological measures, growth, or sprint speed of the offspring. This may reflect a lack of sensitivity of relevant embryonic tissues to corticosterone under the conditions of the present experiment or an ability of the embryos to bind, degrade, or restrict placental transport of corticosterone. Future studies should investigate the possibility of corticosteroid effects on other offspring tissues, including effects in adult life.

Influence of reproductive state on pituitary-adrenal activity in the ewe

Plasma corticosteroid concentrations are altered in pregnancy, during the reproductive cycle and by ovariectomy in many species. This study was designed to examine basal ACTH and cortisol in ewes of four different reproductive statuses: ovariectomized, nonpregnant cycling, nonpregnant noncycling, and pregnant. Blood samples were drawn every 4 hr for 48 hr from ewes during quiet, undisturbed conditions and analyzed for plasma ACTH, cortisol and progesterone concentrations. There were no significant changes in ACTH, cortisol or progesterone over time. Mean progesterone concentrations were significantly greater in the pregnant ewes than in all other ewes, and were greater in cycling ewes than noncycling or ovariectomized ewes. Mean ACTH was significantly greater in pregnant ewes than noncycling ewes, and mean cortisol was significantly greater in cycling ewes than in nonpregnant cycling or noncycling ewes. Ovariectomized ewes also had significantly greater mean cortisol concentrations than cycling ewes. The results demonstrate that there is an increase in basal ACTH and cortisol in ovine pregnancy.

Ingestive Behavior

In summary, horses spend 60% or more of their time eating when grazing or when feed is available free choice. Grasses are their preferred food, but they supplement the grass with herbs and woody plants. Sweetened mixtures of oats and corn are the most preferred concentrate. Horses can increase or decrease the time spent eating and amount eaten to maintain caloric intake. Their intake is stimulated by drugs such as diazepam and by the presence of other horses. Horses stop eating when gastric osmolality increases; increases in plasma osmolality, protein, and glucose accompany digestion. Foals eat several times an hour and begin sampling solid food at the same time that their dam is eating. Several areas of particular importance to the equine industry have not been investigated. These areas include the effect of exercise on short- and long-term food intake and the influence of reproductive state on the feeding of mares.

The influence of reproductive state on infanticide by wild female house mice (Mus musculus)

The majority of female mice (Mus musculus) from laboratory stocks are spontaneously parental. In contrast, the majority of adult wild female house mice exhibit infanticide (the killing of preweanling young), but the frequency with which infanticide is observed varies as a function of age and reproductive state. Prepubertal females were less likely to exhibit infanticide (39%) than were adult virgin females (61%). The frequency of infanticide increased during pregnancy, with over 90% of females exhibiting infanticide just before parturition. But, after parturition, previously infanticidal females cared for their own litters. When lactating female mice were tested after two days of separation from their own nursing young for their behavior toward a novel newborn pup on either the tenth or twenty-fifth day after parturition, the proportion of the females that exhibited infanticide was not significantly different from that of adult virgin females (about 60%). After only two hours of separation from their own nursing young on the tenth day after parturition, however, all females continued to exhibit parental behavior toward a novel pup.

Influence of reproductive state on intestinal fluid and ion transport by the rat jejunum, in relation to the possible contribution of prolactin: Mainoya, J.R.: J. Endocr. [formula omitted]: 351, 1975. Dept. of Zoology and Cancer Res. Lab., Univ. of California, Berkeley, California 94720, U.S.A.

Influence of reproductive state on intestinal fluid and ion transport by the rat jejunum, in relation to the possible contribution of prolactin: Mainoya, J.R.: J. Endocr. [formula omitted]: 351, 1975. Dept. of Zoology and Cancer Res. Lab., Univ. of California, Berkeley, California 94720, U.S.A.