Comparison of different drying and storage methods on quantifiable concentrations of fecal steroids in the cheetah

Abstract 10.1002/zoo.10036.abs Fecal steroid analysis is a powerful tool that can provide important information on the health, physiology, and reproductive status of nondomestic species. However, studying free-ranging animals requires that feces be stored and transported from the collection site to the laboratory in a manner that prevents degradation or alteration of steroid metabolites. To determine […]

Male morphs in tree lizards have different testosterone responses to elevated levels of corticosterone

Changes in circulating glucocorticoid and androgen levels mediate agonistic behaviors in many vertebrates. Individual variation in the magnitude of the glucocorticoid response to stressful stimuli, the negative effects of elevated glucocorticoid levels on androgen levels, or both could mediate individual differences in subsequent agonistic behavior. In a series of previous studies, we found that both […]

Plasma steroid concentrations change in response to sexual behavior in Bufo marinus

Steroid hormone concentrations change in response to social or environmental stimuli in many vertebrates. To test this phenomenon in an amphibian, we examined plasma androgen (A) and corticosterone (B) concentrations in male marine toads (Bufo marinus), a tropical species exhibiting intermale competition, amplectic clasping of females, and bouts of breeding behavior following rains. When males […]

Relationship between androgens, environmentalfactors and reproductive behavior in male white rhinoceros (Ceratotherium simum simum)

We conducted a longitudinal study of the endocrine activity of free-range male white rhinos. An enzyme immunoassay to measure androgens in the feces was developed and validated to show that it can be used to study testicular activity. We identified two fecal metabolites similar to testosterone and dihydrotestosterone. Several lines of evidence suggest that these […]

Glucocorticoid and androgen signaling pathways diverge between advertisement calling and non-calling fish

Behavioral and neuroendocrine mechanisms of social vocalization in teleost fish are influenced by the glucocorticoid cortisol and the androgen 11-ketotestosterone (11kT). The relative abundance of both 11kT, which binds to androgen receptors (ARα, ARβ), and cortisol, which binds to glucocorticoid receptors (GR-1, GR-2), is regulated by 11β-hydroxylase (11βH) that converts 11-deoxycortisol to cortisol and testosterone […]

Digit ratio, polychromatism and associations with endurance and antipredator behaviour in male painted dragon lizards

Variation in sex hormone exposure during early embryonic development contributes to individual differences in behaviour and cognitive abilities later in life. Digit ratio has gained considerable interest as a putative marker for early androgen/oestrogen exposure in behavioural ecology research. Studying digit ratio in nonhuman laboratory as well as wild vertebrate species may be useful to […]

‘Roid rage in rats? Testosterone effects on aggressive motivation, impulsivity and tyrosine hydroxylase

Abstract In humans and animals, anabolic-androgenic steroids (AAS) increase aggression, but the underlying behavioral mechanisms are unclear. AAS may increase the motivation to fight. Alternatively, AAS may increase impulsive behavior, consistent with the popular image of ‘roid rage. To test this, adolescent male rats were treated chronically with testosterone (7.5 mg/kg) or vehicle and tested […]

Sex differences and similarities in the neuroendocrine regulation of social behavior in an African cichlid fish

An individual’s position in a social hierarchy profoundly affects behavior and physiology through interactions with community members, yet little is known about how the brain contributes to status differences between and within the social states or sexes. We aimed to determine sex-specific attributes of social status by comparing circulating sex steroid hormones and neural gene […]

Evaluating the physiological and behavioral response of a male and female gorilla (Gorilla gorilla gorilla) during an introduction

Prolonged stress responses can lead to infertility and death; therefore monitoring respective indicators like stress-related hormones and behaviors is an important tool in ensuring the health and well-being among zoo-housed animal populations. Changes in social structure, such as the introduction of a new conspecific, can be a source of stress. In April 2010, a sexually […]

Social behavior and patterns of testosterone and glucocorticoid levels differ between male chacma and Guinea baboons

In multi-male, multi-female groups of mammals, males usually compete aggressively over access to females. However, species vary in the intensity of male contest competition, which has been linked to differences in testosterone and glucocorticoid profiles. Chacma (Papio ursinus) and Guinea (P. papio) baboons constitute an intriguing model to examine variation in male competition and male […]