[Oxytocin and vasopressin: sexual differences and clinical implications].

Oxytocin and vasopressin share a similar chemical structure but have different functions. Both hormones are produced in different brain areas, are transported through the hypophyseal portal system, pass to the anterior hypophysis, and released to reach their target organs. These hormones also act as neuromodulators, where its receptors are found in the lateral septum, the middle amygdala, the hippocampus, the hypothalamus, and the brain stem.

The effects of female-male friendships on male postcopulatory levels of oxytocin and vasopressin, and sperm parameters in Macacaarctoides.

Male and female stump-tailed macaques (Macaca arctoides) form close relationships akin to human friendships. Oxytocin and vasopressin modulate these and other social relationships and reproductive behavior and physiology in various mammal species. Besides the behavioral effects of oxytocin, this hormone plays an essential role in the ejaculatory process, favoring sperm transport upward the female reproductive tract.

Potential Food Availability Influences Social Interactions of Young Individuals in a Neotropical Primate (Alouatta palliata).

Deforestation is widely recognised as an agent of human disturbance that causes widespread destruction of species habitats and can result in animals occupying forest patches with limited food resources. When animals are forced to change habitats, they must also adjust their diet, activity budgets and social behaviour in response to facing new ecological and environmental conditions. Only a few studies have analysed the influence of habitat conditions on social interactions of immature howler monkeys.

Annual variations in sexual hormones and births' frequency in female stump-tailed macaques (Macaca arctoides).

Although the breeding seasonality in Macaca arctoides have been studied over a long period of time, it is still controversial whether reproduction in this primate tend to increase during certain months of the year as it happens in most of the macaque species. Many authors have classified Macaca arctoides as not being seasonal species. Nonetheless, there were no reports, about seasonal variations of female sexual hormones to demonstrate that asseveration.

Testosterone, the progesterone/estradiol ratio, and female ratings of masculine facial fluctuating asymmetry for a long-term relationship.

Idiosyncratic variation within the normal range of androgens levels in women account for significant variations in personality and behavior. We studied if testosterone introduces significant biases in women's perception of fluctuating symmetry of male faces suitability for a long-term relationship. Participants were 145 female college students asked to rate in a two-choice forced paradigm the attractiveness, suitability as a long-term partner, and economic success, fatherliness and fidelity of an asymmetric and a symmetric male face.

Waist-to-Hip Ratio, but Not Body Mass Index, Is Associated with Testosterone and Estradiol Concentrations in Young Women.

We studied if testosterone and estradiol concentrations are associated with specific female waist-to-hip ratios (WHRs) and body mass indices (BMIs). Participants were 187 young women from which waist, hips, weight, and height were measured. In addition, participants informed on which day of their menstrual cycle they were and provided a 6 mL saliva sample.

Effect of photoperiod on characteristics of semen obtained by electroejaculation in stump-tailed macaques (Macaca arctoides).

Some environmental variables determining seasonal reproduction in mammals are temperature, humidity, food availability, and photoperiod. Among these, photoperiod is considered the main regulator of primates' seasonal reproduction, thus the latitudinal distribution of primate populations is a key factor determining the appearance of seasonal reproduction. The present work presents supporting discrete seasonality in male stump-tailed macaques (Macaca arctoides).

Changes in Men's Salivary Testosterone and Cortisol Levels, and in Sexual Desire after Smelling Female Axillary and Vulvar Scents.

Several studies have shown that a woman's vaginal or axillary odors convey information on her attractivity. Yet, whether such scents induce psychoneuroendocrinological changes in perceivers is still controversial. We studied if smelling axillary and vulvar odors collected in the periovulatory and late luteal phases of young women modify salivary testosterone and cortisol levels, as well as sexual desire in men.

Housing with females increases testosterone and cortisol levels in captive groups of black-handed spider monkeys (Ateles geoffroyi).

The black-handed spider monkey (Ateles geoffroyi) is a seasonal reproducer that requires a seclusiveness to copulate and has a fusion-fission social system. These features impose important restrictions to achieve reproduction of captive animals. We investigated if group composition in captive spider monkeys has any endocrine effects.

Aging-related reproductive decline in the male spider monkey (Ateles geoffroyi).

Background: It is unknown whether male black-handed spider monkeys (Ateles geoffroyi) undergo a reproductive decline as they age. The purpose of this work was investigating whether serum testosterone and semen quality decrease with age in these primates as occur in other species.

Methods: In this study, we assessed age variations in the concentration of serum testosterone, sperm counts, and motility in nine males.

Age-dependent changes in fecal 17beta-estradiol and progesterone concentrations in female spider monkeys (Ateles geoffroyi).

The objective of this study was to investigate whether sex steroids decreased with age in female black-handed spider monkeys (Ateles geoffroyi). Fecal concentrations of 17beta-estradiol and progesterone (five samples/wk) and the number of ovulatory and anovulatory cycles were compared between adult (n=3) and aged females (n=2). All animals (regardless of age) had higher 17beta-estradiol concentrations during the fertile than the nonfertile phases.

Seasonality of LH, testosterone and sperm parameters in spider monkey males (Ateles geoffroyi).

There are no reported data on hormonal fluctuations in black-handed spider monkey males. On previous research about the reproductive physiology of this monkey we have found that during the dry season females show ovulatory estrogen peaks and males present the best quality semen. As part of an ongoing research, in this study we assessed seasonal variations in the concentration of serum luteinizing hormone (LH) and testosterone (T) in three adult spider monkey males to corroborate the seasonal reproductive synchrony.

The seminal coagulum favours passage of fast-moving sperm into the uterus in the black-handed spider monkey.

In addition to gametes, mammalian internal fertilisation has required the evolution of assorted anatomical, physiological and biochemical devices to deal with intra- and inter-sexual conflict such as sperm competition and female cryptic choice respectively. The seminal coagulum of primates and other mammals is viewed as one of such devices. Among primates, the seminal coagulum characteristically occurs in multi-male and multi-female species, leading us to suppose that it intervenes in sperm competition.

Seasonal emission of seminal coagulum and in vivo sperm dynamics in the black-handed spider monkey (Ateles geoffroyi).

The ejaculate of diverse primate species consists of two portions, liquid and solid; the latter, known as the seminal coagulum, is thought to sequester large numbers of sperm. In the black-handed spider monkey (Ateles geoffroyi), ejaculates collected by electroejaculation did not always contain seminal coagulum. The objective of the present study was to determine seasonal emission of seminal coagulum and in vivo sperm dynamics in the black-handed spider monkey.

Innovative social behavior in chimpanzees (Pan troglodytes).

We present evidence of agonistic buffering in captive chimpanzees, recorded from 1993 until 2005, mainly from ad libitum sampling in over 2000 hr of observation. A total of 33 agonistic buffering episodes were analyzed for context and effects of this complex social behavior. Agonistic buffering was directed at the whole chimpanzee colony as they supported an individual who initially received aggression from the alpha male, independently of the victim's age, sex or social rank.

Artificial insemination in black-handed spider monkey (Ateles geoffroyi).

Artificial insemination (AI) was performed in spider monkeys; these primates are vulnerable to extinction and usually do not reproduce spontaneously in captivity. Uterine cycles were followed by daily assessment of vaginal cytology, and corroborated a posteriori by concentrations of 17-beta estradiol and progesterone, measured by radioimmunoassay (RIA), in fecal samples collected once daily. Five females between 13 to 27 years old were inseminated intravaginally (with fresh semen) twice each during the periovulatory phase (Days 9-12 of the menstrual cycle; Day 0, first day of menstrual bleeding), from September to the first 3 weeks of November (most fertile months).

Seasonal variations of fecal progesterone and 17beta-estradiol in captive female black-handed spider monkeys (Ateles geoffroyi).

A number of studies in free-ranging and captive spider monkeys (Ateles spp.) have shown that this genus is able to reproduce throughout the entire year. Nonetheless, it is still controversial whether births, and therefore conceptions, tend to be more frequent during certain seasons.

Endocrine changes in male stumptailed macaques (Macaca arctoides) as a response to odor stimulation with vaginal secretions.

In mammalian species, social chemosignals are important in modulating endocrine reproductive functions. In nonhuman primates, previous studies have described a high frequency of mounting behavior by females in the follicular and periovulatory phases of the menstrual cycle. Stumptailed macaque females do not signal receptivity by means of sexual swellings, as do others macaques, therefore providing a good model in which to study chemical signaling of reproductive status.

Comparison of the effects of Percoll and PureSperm on the common marmoset (Callithrix jacchus) semen.

Density gradient centrifugation is a widely used technique for the separation of motile from non-motile sperm, for the removal of contaminating agents such as bacteria and viruses, and for the removal of seminal plasma or cryoprotectant. In the choice of a density gradient medium for a new species, it is important to perform toxicity tests. The present study was carried out to evaluate the potential toxic effects of two silica-based density gradient products (Percoll and PureSperm), on the sperm of the common marmoset.

Sperm quality differences between the rainy and dry seasons in captive black-handed spider monkeys (Ateles geoffroyi).

The present work provides an assessment of sperm measures (concentration, motility, viability, etc.) of three black-handed spider monkeys (Ateles geoffroyi) during the rainy and dry seasons in Mexico City, as well as an evaluation of the between-subjects variability of sperm quality. Twenty samples obtained by rectal electroejaculation and digested with trypsin were evaluated.

The menstrual cycle of the spider monkey (Ateles geoffroyi).

The ovarian cycles of four adult female spider monkeys (Ateles geoffroyi) were followed daily throughout 30 days by means of vaginal swabs and blood samplings. Cytological analyses of the vaginal swabs and radioimmunoassay determination of the daily levels of estradiol-17 beta (E2) and progesterone (P4) wer done in order to classify the kind of ovarian cycle of this species. Our results show that Ateles geoffroyi females display menstrual cycles of about 24 days on average.

Transient emotional changes elicited by intraperitoneal saline injection: effect of naloxone and flumazenil.

The effect of the intraperitoneal (i.p.) saline injection was assessed by using the defensive burying (DB) and the elevated plus-maze (EPM) anxiety paradigms in rats.

Enforced water drinking induces changes in burying behavior and social interaction test in rats.

The effect of water deprivation and water intake on experimental anxiety in rats was tested using burying behavior (BB) and social interaction (SI) anxiety paradigms. Two groups of animals were studied: a control group with free access to water, and a 72-h water-deprived experimental group. Anxiety was studied in a water-deprived group or following a 10-min period of ad lib water drinking.

Exposure to the social interaction test in rats induces changes in defensive burying.

To detect changes in experimental anxiety, defensive burying (DB) was studied in several groups of rats after being exposed to social interaction (SI). Animals were studied in the DB paradigm after being submitted to the following SI treatments: control (without SI exposure), and SI for 1.5, 5, 10 and 15 min respectively.