Brown ratThe brown rat (Rattus norvegicus), also known as the common rat, street rat, sewer rat, wharf rat, Hanover rat, Norway rat and Norwegian rat, is a widespread species of common rat. One of the largest muroids, it is a brown or grey rodent with a head and body length of up to long, and a tail slightly shorter than that. It weighs between . Thought to have originated in northern China and neighbouring areas, this rodent has now spread to all continents except Antarctica, and is the dominant rat in Europe and much of North America.
Laboratory ratLaboratory rats or lab rats are strains of the subspecies Rattus norvegicus domestica which are bred and kept for scientific research. While less commonly used for research than laboratory mice, rats have served as an important animal model for research in psychology and biomedical science. In 18th century Europe, wild brown rats (Rattus norvegicus) ran rampant and this infestation fueled the industry of rat-catching. Rat-catchers would not only make money by trapping the rodents, but also by selling them for food or, more commonly, for rat-baiting.
Adrenocorticotropic hormoneAdrenocorticotropic hormone (ACTH; also adrenocorticotropin, corticotropin) is a polypeptide tropic hormone produced by and secreted by the anterior pituitary gland. It is also used as a medication and diagnostic agent. ACTH is an important component of the hypothalamic-pituitary-adrenal axis and is often produced in response to biological stress (along with its precursor corticotropin-releasing hormone from the hypothalamus). Its principal effects are increased production and release of cortisol and androgens by the cortex and medulla of the adrenal gland, respectively.
Precocious pubertyIn medicine, precocious puberty is puberty occurring at an unusually early age. In most cases, the process is normal in every aspect except the unusually early age and simply represents a variation of normal development. In a minority of children with precocious puberty, the early development is triggered by a disease such as a tumor or injury of the brain.
PreadolescencePreadolescence is a stage of human development following middle childhood and preceding adolescence. It commonly ends with the beginning of puberty. Preadolescence is commonly defined as ages 9–12 ending with the major onset of puberty. It may also be defined as simply the 2-year period before the major onset of puberty. Preadolescence can bring its own challenges and anxieties. A term used to refer to the preadolescent stage in everyday speech is tween and its perhaps older variants tweenie, tweeny, tweenager, and tweener.
EstradiolEstradiol (E2), also spelled oestradiol, is an estrogen steroid hormone and the major female sex hormone. It is involved in the regulation of the estrous and menstrual female reproductive cycles. Estradiol is responsible for the development of female secondary sexual characteristics such as the breasts, widening of the hips and a female-associated pattern of fat distribution. It is also important in the development and maintenance of female reproductive tissues such as the mammary glands, uterus and vagina during puberty, adulthood and pregnancy.
Adrenal cortexThe adrenal cortex is the outer region and also the largest part of an adrenal gland. It is divided into three separate zones: zona glomerulosa, zona fasciculata and zona reticularis. Each zone is responsible for producing specific hormones. It is also a secondary site of androgen synthesis. The adrenal cortex comprises three main zones, or layers that are regulated by distinct hormones as noted below. This anatomic zonation can be appreciated at the microscopic level, where each zone can be recognized and distinguished from one another based on structural and anatomic characteristics.
Steroid 11β-hydroxylaseSteroid 11β-hydroxylase, also known as steroid 11β-monooxygenase, is a steroid hydroxylase found in the zona glomerulosa and zona fasciculata of the adrenal cortex. Named officially the cytochrome P450 11B1, mitochondrial, it is a protein that in humans is encoded by the CYP11B1 gene. The enzyme is involved in the biosynthesis of adrenal corticosteroids by catalyzing the addition of hydroxyl groups during oxidation reactions. The CYP11B1 gene encodes 11β-hydroxylase - a member of the cytochrome P450 superfamily of enzymes.
PubertyPuberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a girl, the testes in a boy. In response to the signals, the gonads produce hormones that stimulate libido and the growth, function, and transformation of the brain, bones, muscle, blood, skin, hair, breasts, and sex organs. Physical growth—height and weight—accelerates in the first half of puberty and is completed when an adult body has been developed.
Stress in early childhoodEarly childhood is a critical period in a child's life that includes ages from conception to five years old. Psychological stress is an inevitable part of life. Human beings can experience stress from an early age. Although stress is a factor for the average human being, it can be a positive or negative molding aspect in a young child's life. A certain amount of stress is normal and necessary for survival.
