Search results for "Estrus"
showing 10 items of 14 documents
Effects of Environmental Lighting and Tryptophan Devoid Diet on the Rat Vaginal Cycle
1998
Cerebral serotonin level influences luteinizing hormone release and, consequently, ovulation. The present study evaluated the effects of precooked maize meal (polenta), a diet almost devoid of tryptophan the serotonin precursor on the alterations of the estrus cycle as measured by vaginal smears analysis in Wistar rats. Several conditions of environmental lighting were used in order to modify ovarian cycle: 1) natural alternating light/dark cycle; 2) continuous darkness; 3) continuous light by sodium steams: 4) continuous light by fluorescent neon tubes. Rats bred in continuous lighting showed estrus-proestrus rate significantly greater than rats bred in normal lighting or in continuous dar…
Therapeutic Perspectives in Psychoneuroendocrinimmunology(PNEI): Potential Role of Phosphatidylserine in Neuroendocrine-Immune Communications
1990
(1990). Therapeutic Perspectives in Psychoneuroendocrinimmunology(PNEI): Potential Role of Phosphatidylserine in Neuroendocrine-Immune Communications. International Journal of Neuroscience: Vol. 51, No. 3-4, pp. 299-301.
Depressive effect of LHRH on the numbers of "synaptic" ribbons and spherules in the pineal gland of diestrous rats.
1983
Previous studies have shown that LHRH or LHRH-like substances are present in the pineal gland. In order to investigate whether exogenous LHRH may affect the pineal gland, in the present study the effects of a single dose of LHRH (1 microgram, i.p.) on pineal "synaptic" ribbons and spherules as well as serum melatonin levels were examined in diestrous Wistar rats. One hour after the injection both ribbons and spherules exhibited a statistically significant decrease in number. Serum melatonin levels were not affected. It is concluded that humoral feedback mechanisms may exist between the hypothalamus and the pineal gland.
Infanticide in the evolution of reproductive synchrony: effects on reproductive success.
2007
Synchronous breeding in animals and plants has stimulated both a theoretical and empirical examination of the possible benefits of active synchronization. The selective pressures of predation and infanticide are the strongest candidates proposed to explain the evolution of reproductive synchrony. Alternatively, breeding asynchronously with conspecifics may ensure a greater availability of resources per breeder. However, the possible fitness benefits resulting from active asynchronization have not yet received attention in evolutionary ecology. Here we present a hypothesis, based on a graphical model, illustrating the costs and benefits of the two modes of reproduction. We tested the hypothe…
Pineal ?synaptic? ribbons and spherules during the estrous cycle in rats
1983
In previous studies pineal "synaptic" ribbons have been shown to undergo striking numerical changes under various physiological and experimental conditions and to be regulated by beta-adrenergic mechanisms. The aim of the present investigation was to study the numbers of pineal "synaptic" ribbons and spherules in Wistar rats throughout the estrous cycle and to compare them with those in males. There were no statistically significant differences in the numbers of ribbons and spherules between males and females and in the females at the different stages of the estrous cycle, indicating that the structures in question, in vivo, do not appear to be regulated by naturally occurring changes of se…
Variable mode of estrus affects female decision for multiple mating
2011
Investigating patterns of variation in mating strategies may shed light on their evolutionary importance as well as their impact on the strength and shape of sexual selection. Multimale mating (polyandry) and mate choice are intensely studied subjects in the area of sexual selection, but little is known about intraspecific patterns of variation that may respond to dynamic cost-benefit balances. In a laboratory study, we investigated the mating behavior of female bank voles (Myodes glareolus) with distinctly different time and energy budgets: They were either in cycling estrus (CE) or postpartum estrus (PPE) shortly after delivery. Postpartum mating is highly constrained by time and energy d…
Effects of LHRH, progesterone, estradiol-17 ? and dexamethasone in vitro on pineal synaptic ribbons and serotonin N-acetyltransferase activity in die…
1991
Pineal glands of regularly cycling Sprague Dawley rats (180-220 g) killed on the diestrous morning (between 0900-1000 h) were incubated in appropriate media for six hours with LHRH (8.5 microM), progesterone (3.2 microM), estradiol-17 beta (370 nM) or dexamethasone (250 nM). Pineals incubated in hormone-free medium and unincubated glands served as controls. Six rats were used in each group. After incubation the glands were divided into two parts. One part was used to estimate serotonin N-acetyltransferase (NAT) activity. The other part was processed for electron microscopy to quantify synaptic ribbons (SR). The SR numbers were computed to 20,000 microns 2 area of pineal tissue. The number a…
Endocrine and ovarian response after a 2-day controlled suckling and eCG treatment in lactating rabbit does.
2006
Synchronization methods are used to obtain higher fertility when artificial insemination (AI) is applied to lactating rabbit does. The most common methods are eCG administration or temporary doe–litter separation. Nevertheless, drawbacks have been reported, such as negative side effects of hormonal treatment in the doe and low litter growth due to absence of suckling, respectively. Recently, improved reproductive performance (without visible consequences on young rabbit growth), has been obtained by applying a 2-day controlled nursing method before AI, by allowing for a 10 min nursing of the litter 24 h of separation. The present study was undertaken to examine the pituitary (PRL, LH, FSH) …
Interrelationship between reproductive hormones and acute phase proteins during estrous cycle and pregnancy in Spanish purebred broodmares
2021
Highlights • Steroid hormones and acute phase proteins in cyclic and pregnant mares were evaluated. • SAA and CRP did not discriminate cyclic and pregnant mares. • Pregnancy induced a limited acute phase response in Spanish purebred mares. • SAA, Hp and CRP were independent of E1 and P4 dynamics during pregnancy.
EFFECT OF A 48H DELAYED INSEMINATION WITH OR WITHOUT A 48H DOE-LITTER SEPARATION ON PERFORMANCE OF NON-RECEPTIVE RABBIT DOES
2010
[EN] The effectiveness of delayed artificial insemination (DAI) of non-receptive (R-) does, with or without oestrus synchronisation by doe-litter separation (MLS), was studied and compared with receptive (R+) does. During 10 months, 105 NZW does, in three homogeneous groups (A, B, C), were artificially inseminated (Al) according to a 42-day reproduction rhythm in two batches. Every 21 days, two Al were effected, the second 48 hours alter the first. The R+ does of ali groups were inseminated al the first Al, while the R- does were treated, in relation to theirgroup, as follows: inseminated at the first Al (A); 48-hour DAI (B); 48-hour MLS by closing the nestbox before Al, when lactating, and…