Corticosterone: An adrenocortical steroid that has modest but significant activities as a mineralocorticoid and a glucocorticoid. (From Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed, p1437)Adrenocorticotropic Hormone: An anterior pituitary hormone that stimulates the ADRENAL CORTEX and its production of CORTICOSTEROIDS. ACTH is a 39-amino acid polypeptide of which the N-terminal 24-amino acid segment is identical in all species and contains the adrenocorticotrophic activity. Upon further tissue-specific processing, ACTH can yield ALPHA-MSH and corticotrophin-like intermediate lobe peptide (CLIP).Adrenalectomy: Excision of one or both adrenal glands. (From Dorland, 28th ed)Pituitary-Adrenal System: The interactions between the anterior pituitary and adrenal glands, in which corticotropin (ACTH) stimulates the adrenal cortex and adrenal cortical hormones suppress the production of corticotropin by the anterior pituitary.Hypothalamo-Hypophyseal System: A collection of NEURONS, tracts of NERVE FIBERS, endocrine tissue, and blood vessels in the HYPOTHALAMUS and the PITUITARY GLAND. This hypothalamo-hypophyseal portal circulation provides the mechanism for hypothalamic neuroendocrine (HYPOTHALAMIC HORMONES) regulation of pituitary function and the release of various PITUITARY HORMONES into the systemic circulation to maintain HOMEOSTASIS.Restraint, Physical: Use of a device for the purpose of controlling movement of all or part of the body. Splinting and casting are FRACTURE FIXATION.Adrenal Glands: A pair of glands located at the cranial pole of each of the two KIDNEYS. Each adrenal gland is composed of two distinct endocrine tissues with separate embryonic origins, the ADRENAL CORTEX producing STEROIDS and the ADRENAL MEDULLA producing NEUROTRANSMITTERS.Stress, Physiological: The unfavorable effect of environmental factors (stressors) on the physiological functions of an organism. Prolonged unresolved physiological stress can affect HOMEOSTASIS of the organism, and may lead to damaging or pathological conditions.Metyrapone: An inhibitor of the enzyme STEROID 11-BETA-MONOOXYGENASE. It is used as a test of the feedback hypothalamic-pituitary mechanism in the diagnosis of CUSHING SYNDROME.Corticotropin-Releasing Hormone: A peptide of about 41 amino acids that stimulates the release of ADRENOCORTICOTROPIC HORMONE. CRH is synthesized by neurons in the PARAVENTRICULAR NUCLEUS of the HYPOTHALAMUS. After being released into the pituitary portal circulation, CRH stimulates the release of ACTH from the PITUITARY GLAND. CRH can also be synthesized in other tissues, such as PLACENTA; ADRENAL MEDULLA; and TESTIS.Receptors, Glucocorticoid: Cytoplasmic proteins that specifically bind glucocorticoids and mediate their cellular effects. The glucocorticoid receptor-glucocorticoid complex acts in the nucleus to induce transcription of DNA. Glucocorticoids were named for their actions on blood glucose concentration, but they have equally important effects on protein and fat metabolism. Cortisol is the most important example.Mifepristone: A progestational and glucocorticoid hormone antagonist. Its inhibition of progesterone induces bleeding during the luteal phase and in early pregnancy by releasing endogenous prostaglandins from the endometrium or decidua. As a glucocorticoid receptor antagonist, the drug has been used to treat hypercortisolism in patients with nonpituitary CUSHING SYNDROME.Stress, Psychological: Stress wherein emotional factors predominate.Transcortin: A serpin family member that binds to and transports GLUCOCORTICOIDS in the BLOOD.Receptors, Mineralocorticoid: Cytoplasmic proteins that specifically bind MINERALOCORTICOIDS and mediate their cellular effects. The receptor with its bound ligand acts in the nucleus to induce transcription of specific segments of DNA.Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Glucocorticoids: A group of CORTICOSTEROIDS that affect carbohydrate metabolism (GLUCONEOGENESIS, liver glycogen deposition, elevation of BLOOD SUGAR), inhibit ADRENOCORTICOTROPIC HORMONE secretion, and possess pronounced anti-inflammatory activity. They also play a role in fat and protein metabolism, maintenance of arterial blood pressure, alteration of the connective tissue response to injury, reduction in the number of circulating lymphocytes, and functioning of the central nervous system.Adrenal Cortex: The outer layer of the adrenal gland. It is derived from MESODERM and comprised of three zones (outer ZONA GLOMERULOSA, middle ZONA FASCICULATA, and inner ZONA RETICULARIS) with each producing various steroids preferentially, such as ALDOSTERONE; HYDROCORTISONE; DEHYDROEPIANDROSTERONE; and ANDROSTENEDIONE. Adrenal cortex function is regulated by pituitary ADRENOCORTICOTROPIN.Rats, Wistar: A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.11-beta-Hydroxysteroid Dehydrogenases: Hydroxysteroid dehydrogenases that catalyzes the reversible conversion of CORTISOL to the inactive metabolite CORTISONE. Enzymes in this class can utilize either NAD or NADP as cofactors.Paraventricular Hypothalamic Nucleus: Nucleus in the anterior part of the HYPOTHALAMUS.Handling (Psychology): Physical manipulation of animals and humans to induce a behavioral or other psychological reaction. In experimental psychology, the animal is handled to induce a stress situation or to study the effects of "gentling" or "mothering".Behavior, Animal: The observable response an animal makes to any situation.Steroid 11-beta-Hydroxylase: A mitochondrial cytochrome P450 enzyme that catalyzes the 11-beta-hydroxylation of steroids in the presence of molecular oxygen and NADPH-FERRIHEMOPROTEIN REDUCTASE. This enzyme, encoded by CYP11B1 gene, is important in the synthesis of CORTICOSTERONE and HYDROCORTISONE. Defects in CYP11B1 cause congenital adrenal hyperplasia (ADRENAL HYPERPLASIA, CONGENITAL).Hormone Antagonists: Chemical substances which inhibit the function of the endocrine glands, the biosynthesis of their secreted hormones, or the action of hormones upon their specific sites.Body Weight: The mass or quantity of heaviness of an individual. It is expressed by units of pounds or kilograms.Swimming: An activity in which the body is propelled through water by specific movement of the arms and/or the legs. Swimming as propulsion through water by the movement of limbs, tail, or fins of animals is often studied as a form of PHYSICAL EXERTION or endurance.Aldosterone: A hormone secreted by the ADRENAL CORTEX that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium.Hydroxysteroid Dehydrogenases: Enzymes of the oxidoreductase class that catalyze the dehydrogenation of hydroxysteroids. (From Enzyme Nomenclature, 1992) EC 1.1.-.11-beta-Hydroxysteroid Dehydrogenase Type 2: An high-affinity, NAD-dependent 11-beta-hydroxysteroid dehydrogenase that acts unidirectionally to catalyze the dehydrogenation of CORTISOL to CORTISONE. It is found predominantly in mineralocorticoid target tissues such as the KIDNEY; COLON; SWEAT GLANDS; and the PLACENTA. Absence of the enzyme leads to a fatal form of childhood hypertension termed, APPARENT MINERALOCORTICOID EXCESS SYNDROME.Dexamethasone: An anti-inflammatory 9-fluoro-glucocorticoid.Circadian Rhythm: The regular recurrence, in cycles of about 24 hours, of biological processes or activities, such as sensitivity to drugs and stimuli, hormone secretion, sleeping, and feeding.Pro-Opiomelanocortin: A 30-kDa protein synthesized primarily in the ANTERIOR PITUITARY GLAND and the HYPOTHALAMUS. It is also found in the skin and other peripheral tissues. Depending on species and tissues, POMC is cleaved by PROHORMONE CONVERTASES yielding various active peptides including ACTH; BETA-LIPOTROPIN; ENDORPHINS; MELANOCYTE-STIMULATING HORMONES; and others (GAMMA-LPH; CORTICOTROPIN-LIKE INTERMEDIATE LOBE PEPTIDE; N-terminal peptide of POMC or NPP).11-beta-Hydroxysteroid Dehydrogenase Type 1: A low-affinity 11 beta-hydroxysteroid dehydrogenase found in a variety of tissues, most notably in LIVER; LUNG; ADIPOSE TISSUE; vascular tissue; OVARY; and the CENTRAL NERVOUS SYSTEM. The enzyme acts reversibly and can use either NAD or NADP as cofactors.Hippocampus: A curved elevation of GRAY MATTER extending the entire length of the floor of the TEMPORAL HORN of the LATERAL VENTRICLE (see also TEMPORAL LOBE). The hippocampus proper, subiculum, and DENTATE GYRUS constitute the hippocampal formation. Sometimes authors include the ENTORHINAL CORTEX in the hippocampal formation.Propanil: A chlorinated anilide that is used as an herbicide.Hypothalamus: Ventral part of the DIENCEPHALON extending from the region of the OPTIC CHIASM to the caudal border of the MAMMILLARY BODIES and forming the inferior and lateral walls of the THIRD VENTRICLE.Adrenal Cortex HormonesMaternal Deprivation: Prolonged separation of the offspring from the mother.Organ Size: The measurement of an organ in volume, mass, or heaviness.Ether: A mobile, very volatile, highly flammable liquid used as an inhalation anesthetic and as a solvent for waxes, fats, oils, perfumes, alkaloids, and gums. It is mildly irritating to skin and mucous membranes.Drug Implants: Small containers or pellets of a solid drug implanted in the body to achieve sustained release of the drug.Receptors, Corticotropin-Releasing Hormone: Cell surface proteins that bind corticotropin-releasing hormone with high affinity and trigger intracellular changes which influence the behavior of cells. The corticotropin releasing-hormone receptors on anterior pituitary cells mediate the stimulation of corticotropin release by hypothalamic corticotropin releasing factor. The physiological consequence of activating corticotropin-releasing hormone receptors on central neurons is not well understood.Neurosecretory Systems: A system of NEURONS that has the specialized function to produce and secrete HORMONES, and that constitutes, in whole or in part, an ENDOCRINE SYSTEM or organ.Analysis of Variance: A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.Desoxycorticosterone: A steroid metabolite that is the 11-deoxy derivative of CORTICOSTERONE and the 21-hydroxy derivative of PROGESTERONE.Exploratory Behavior: The tendency to explore or investigate a novel environment. It is considered a motivation not clearly distinguishable from curiosity.Crowding: An excessive number of individuals, human or animal, in relation to available space.Methylhistidines: Histidine substituted in any position with one or more methyl groups.Mineralocorticoids: A group of CORTICOSTEROIDS primarily associated with water and electrolyte balance. This is accomplished through the effect on ION TRANSPORT in renal tubules, resulting in retention of sodium and loss of potassium. Mineralocorticoid secretion is itself regulated by PLASMA VOLUME, serum potassium, and ANGIOTENSIN II.Radioimmunoassay: Classic quantitative assay for detection of antigen-antibody reactions using a radioactively labeled substance (radioligand) either directly or indirectly to measure the binding of the unlabeled substance to a specific antibody or other receptor system. Non-immunogenic substances (e.g., haptens) can be measured if coupled to larger carrier proteins (e.g., bovine gamma-globulin or human serum albumin) capable of inducing antibody formation.Hydrocortisone: The main glucocorticoid secreted by the ADRENAL CORTEX. Its synthetic counterpart is used, either as an injection or topically, in the treatment of inflammation, allergy, collagen diseases, asthma, adrenocortical deficiency, shock, and some neoplastic conditions.18-Hydroxycorticosterone: 11 beta,18,21-Trihydroxypregn-4-ene-3,20-dione.Maze Learning: Learning the correct route through a maze to obtain reinforcement. It is used for human or animal populations. (Thesaurus of Psychological Index Terms, 6th ed)Immobilization: The restriction of the MOVEMENT of whole or part of the body by physical means (RESTRAINT, PHYSICAL) or chemically by ANALGESIA, or the use of TRANQUILIZING AGENTS or NEUROMUSCULAR NONDEPOLARIZING AGENTS. It includes experimental protocols used to evaluate the physiologic effects of immobility.Hormones: Chemical substances having a specific regulatory effect on the activity of a certain organ or organs. The term was originally applied to substances secreted by various ENDOCRINE GLANDS and transported in the bloodstream to the target organs. It is sometimes extended to include those substances that are not produced by the endocrine glands but that have similar effects.Steroids: A group of polycyclic compounds closely related biochemically to TERPENES. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (STEROLS), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. (From Hawley's Condensed Chemical Dictionary, 11th ed)Time Factors: Elements of limited time intervals, contributing to particular results or situations.Anxiety: Feeling or emotion of dread, apprehension, and impending disaster but not disabling as with ANXIETY DISORDERS.Amygdala: Almond-shaped group of basal nuclei anterior to the INFERIOR HORN OF THE LATERAL VENTRICLE of the TEMPORAL LOBE. The amygdala is part of the limbic system.Anti-Inflammatory Agents: Substances that reduce or suppress INFLAMMATION.Cortodoxone: 17,21-Dihydroxypregn-4-ene-3,20-dione. A 17-hydroxycorticosteroid with glucocorticoid and anti-inflammatory activities.Rats, Inbred Strains: Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.Aldosterone Synthase: A mitochondrial cytochrome P450 enzyme that catalyzes the 18-hydroxylation of steroids in the presence of molecular oxygen and NADPH-specific flavoprotein. This enzyme, encoded by CYP11B2 gene, is important in the conversion of CORTICOSTERONE to 18-hydroxycorticosterone and the subsequent conversion to ALDOSTERONE.Eating: The consumption of edible substances.Testosterone: A potent androgenic steroid and major product secreted by the LEYDIG CELLS of the TESTIS. Its production is stimulated by LUTEINIZING HORMONE from the PITUITARY GLAND. In turn, testosterone exerts feedback control of the pituitary LH and FSH secretion. Depending on the tissues, testosterone can be further converted to DIHYDROTESTOSTERONE or ESTRADIOL.Zona Reticularis: The inner zone of the adrenal cortex. This zone produces the enzymes that convert PREGNENOLONE, a 21-carbon steroid, to 19-carbon steroids (DEHYDROEPIANDROSTERONE; and ANDROSTENEDIONE) via 17-ALPHA-HYDROXYPREGNENOLONE.Mice, Inbred C57BLZona Fasciculata: The wide middle zone of the adrenal cortex. This zone produces a series of enzymes that convert PREGNENOLONE to cortisol (HYDROCORTISONE) via 17-ALPHA-HYDROXYPROGESTERONE.Cortisone: A naturally occurring glucocorticoid. It has been used in replacement therapy for adrenal insufficiency and as an anti-inflammatory agent. Cortisone itself is inactive. It is converted in the liver to the active metabolite HYDROCORTISONE. (From Martindale, The Extra Pharmacopoeia, 30th ed, p726)Motor Activity: The physical activity of a human or an animal as a behavioral phenomenon.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Feathers: Flat keratinous structures found on the skin surface of birds. Feathers are made partly of a hollow shaft fringed with barbs. They constitute the plumage.RNA, Messenger: RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.Social Isolation: The separation of individuals or groups resulting in the lack of or minimizing of social contact and/or communication. This separation may be accomplished by physical separation, by social barriers and by psychological mechanisms. In the latter, there may be interaction but no real communication.Animals, Newborn: Refers to animals in the period of time just after birth.Sparrows: The family Passeridae comprised of small, mainly brown and grey seed-eating birds with conical bills.Injections, Intraventricular: Injections into the cerebral ventricles.Housing, AnimalSolar Activity: Any type of variation in the appearance of energy output of the sun. (NASA Thesaurus, 1994)Progesterone: The major progestational steroid that is secreted primarily by the CORPUS LUTEUM and the PLACENTA. Progesterone acts on the UTERUS, the MAMMARY GLANDS and the BRAIN. It is required in EMBRYO IMPLANTATION; PREGNANCY maintenance, and the development of mammary tissue for MILK production. Progesterone, converted from PREGNENOLONE, also serves as an intermediate in the biosynthesis of GONADAL STEROID HORMONES and adrenal CORTICOSTEROIDS.Hydroxyprogesterones: Metabolites or derivatives of PROGESTERONE with hydroxyl group substitution at various sites.Biogenic Monoamines: Biogenic amines having only one amine moiety. Included in this group are all natural monoamines formed by the enzymatic decarboxylation of natural amino acids.Oviparity: The capability of producing eggs (OVA) from which young are hatched outside the body. While mostly referring to nonmammalian species, this does include MAMMALS of the order MONOTREMATA.Arginine Vasopressin: The predominant form of mammalian antidiuretic hormone. It is a nonapeptide containing an ARGININE at residue 8 and two disulfide-linked cysteines at residues of 1 and 6. Arg-vasopressin is used to treat DIABETES INSIPIDUS or to improve vasomotor tone and BLOOD PRESSURE.Carbenoxolone: An agent derived from licorice root. It is used for the treatment of digestive tract ulcers, especially in the stomach. Antidiuretic side effects are frequent, but otherwise the drug is low in toxicity.Electroshock: Induction of a stress reaction in experimental subjects by means of an electrical shock; applies to either convulsive or non-convulsive states.Pituitary Gland: A small, unpaired gland situated in the SELLA TURCICA. It is connected to the HYPOTHALAMUS by a short stalk which is called the INFUNDIBULUM.Iguanas: Large herbivorous tropical American lizards.Disease Models, Animal: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.Nesting Behavior: Animal behavior associated with the nest; includes construction, effects of size and material; behavior of the adult during the nesting period and the effect of the nest on the behavior of the young.Hypophysectomy: Surgical removal or destruction of the hypophysis, or pituitary gland. (Dorland, 28th ed)Phenelzine: One of the MONOAMINE OXIDASE INHIBITORS used to treat DEPRESSION; PHOBIC DISORDERS; and PANIC.Feeding Behavior: Behavioral responses or sequences associated with eating including modes of feeding, rhythmic patterns of eating, and time intervals.Food Deprivation: The withholding of food in a structured experimental situation.