Testosterone is the primary sex hormone and anabolic steroid in males. In male humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristics such as increased muscle and bone mass, and the growth of body hair. In addition, testosterone in both sexes is involved in health and well-being and in the prevention of osteoporosis. Insufficient levels of testosterone in men may lead to abnormalities including frailty and bone loss.
Aggression is overt or covert, often harmful, social interaction with the intention of inflicting damage or other harm upon another individual. It may occur either reactively or without provocation. In humans, aggression can be caused by various triggers, from frustration due to blocked goals to feeling disrespected. Human aggression can be classified into direct and indirect aggression; whilst the former is characterized by physical or verbal behavior intended to cause harm to someone, the latter is characterized by behavior intended to harm the social relations of an individual or group.
The digit ratio is the ratio of the lengths of different digits or fingers. The 2D:4D ratio is the most studied digit ratio and is calculated by dividing the length of the index finger of a given hand by the length of the ring finger of the same hand. A number of studies have shown a correlation between the 2D:4D digit ratio and various physical and behavioral traits.
Forkhead box protein P2 (FOXP2) is a protein that, in humans, is encoded by the FOXP2 gene. FOXP2 is a member of the forkhead box family of transcription factors, proteins that regulate gene expression by binding to DNA. It is expressed in the brain, heart, lungs and digestive system.
The house mouse is a small mammal of the order Rodentia, characteristically having a pointed snout, large rounded ears, and a long and hairy tail. It is one of the most abundant species of the genus Mus. Although a wild animal, the house mouse has benefited significantly from associating with human habitation to the point that truly wild populations are significantly less common than the semi-tame populations near human activity.
The laboratory mouse or lab mouse is a small mammal of the order Rodentia which is bred and used for scientific research. Laboratory mice are usually of the species Mus musculus. They are the most commonly used mammalian research model and are used for research in genetics, psychology, medicine and other scientific disciplines. Mice belong to the Euarchontoglires clade, which includes humans. This close relationship, the associated high homology with humans, their ease of maintenance and handling, and their high reproduction rate, make mice particularly suitable models for human-oriented research. The laboratory mouse genome has been sequenced and many mouse genes have human homologues.
The pinyon mouse is native to the southwestern United States and Baja California in Mexico. These medium-sized mice are often distinguished by their relatively large ears. The range of this species extends from southern Oregon and Wyoming in the north, and extends south to roughly the U.S.-Mexico border, with a disjunct population designated as Peromyscus true comanche that occupies an area in the vicinity of Palo Duro Canyon in the Texas panhandle.
The California mouse is a species of rodent in the subfamily Neotominae in the family Cricetidae. It is the only species in the Peromyscus californicus species group. It is found in northwestern Mexico and central to southern California. It is the largest Peromyscus species in the United States.
Alston's brown mouse, also called Alston's singing mouse, short-tailed singing mouse, or singing mouse, is a species of rodent in the family Cricetidae. It is found in Central America, from Chiapas, Mexico, to western Panama.
Scotinomys is a genus of rodent, the singing mice, in the family Cricetidae. Together with Baiomys, it forms the tribe Baiomyini. It contains the following species:
Agonistic behaviour is any social behaviour related to fighting. The term has broader meaning than aggressive behaviour because it includes threats, displays, retreats, placation, and conciliation. The term "agonistic behaviour" was first implemented by J.P Scott and Emil Fredericson in 1951 in their paper "The Causes of Fighting in Mice and Rats" in Physiological Zoology. Agonistic behaviour is seen in many animal species because resources including food, shelter, and mates are often limited.
Transforming growth factor beta-1-induced transcript 1 protein is a protein that in humans is encoded by the TGFB1I1 gene.
Rodents are mammals of the order Rodentia, which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are native to all major land masses except for New Zealand, Antarctica, and several oceanic islands, though they have subsequently been introduced to most of these land masses by human activity.
Major urinary proteins (Mups), also known as α2u-globulins, are a subfamily of proteins found in abundance in the urine and other secretions of many animals. Mups provide a small range of identifying information about the donor animal, when detected by the vomeronasal organ of the receiving animal. They belong to a larger family of proteins known as lipocalins. Mups are encoded by a cluster of genes, located adjacent to each other on a single stretch of DNA, that varies greatly in number between species: from at least 21 functional genes in mice to none in humans. Mup proteins form a characteristic glove shape, encompassing a ligand-binding pocket that accommodates specific small organic chemicals.
The Bruce effect, or pregnancy block, is the tendency for female rodents to terminate their pregnancies following exposure to the scent of an unfamiliar male. The effect was first noted in 1959 by Hilda M. Bruce, and has primarily been studied in laboratory mice. In mice, pregnancy can only be terminated prior to embryo implantation, but other species will interrupt even a late-term pregnancy.
MDN1, midasin homolog (yeast) is a protein that in humans is encoded by the MDN1 gene. Midasin is a member AAA ATPase family.
The challenge hypothesis outlines the dynamic relationship between testosterone and aggression in mating contexts. It proposes that testosterone promotes aggression when it would be beneficial for reproduction, such as mate guarding, or strategies designed to prevent the encroachment of intrasexual rivals. The positive correlation between reproductive aggression and testosterone levels is seen to be strongest during times of social instability. The challenge hypothesis predicts that seasonal patterns in testosterone levels are a function of mating system, paternal care, and male-male aggression in seasonal breeders.
Prenatal Testosterone Transfer refers to the phenomenon in which testosterone synthesized by a developing male fetus transfers to one or more developing fetuses within the womb and influences development. This typically results in the partial masculinization of specific aspects of female behavior, cognition, and morphology, though some studies have found that testosterone transfer can cause an exaggerated masculinization in males. There is strong evidence supporting the occurrence of prenatal testosterone transfer in rodents and other litter-bearing species, such as pigs. When it comes to humans, studies comparing dizygotic opposite-sex and same-sex twins suggest the phenomenon may occur, though the results of these studies are often inconsistent.
3β-Androstanediol, also known as 5α-androstane-3β,17β-diol, and sometimes shortened in the literature to 3β-diol, is an endogenous steroid hormone and a metabolite of androgens like dehydroepiandrosterone (DHEA) and dihydrotestosterone (DHT).
Acetothiolutamide is a selective androgen receptor modulator (SARM) derived from the nonsteroidal antiandrogen bicalutamide that was described in 2002 and was one of the first SARMs to be discovered and developed. It is a high-affinity, selective ligand of the androgen receptor (AR), where it acts as a full agonist in vitro, and has in vitro potency comparable to that of testosterone. However, in vivo, acetothiolutamide displayed overall negligible androgenic effects, though significant anabolic effects were observed at high doses. In addition, notable antiandrogen effects were observed in castrated male rats treated with testosterone propionate. The discrepancy between the in vitro and in vivo actions of acetothiolutamide was determined to be related to rapid plasma clearance and extensive hepatic metabolism into a variety of metabolites with differing pharmacological activity, including AR partial agonism and antagonism. In accordance with its poor metabolic stability, acetothiolutamide is not orally bioavailable, and shows activity only via injected routes such as subcutaneous and intravenous.
