One of the three major families of endogenous opioid peptides. The enkephalins are pentapeptides that are widespread in the central and peripheral nervous systems and in the adrenal medulla.

The principal alkaloid in opium and the prototype opiate analgesic and narcotic. Morphine has widespread effects in the central nervous system and on smooth muscle.

An enkephalin analog that selectively binds to the MU OPIOID RECEPTOR. It is used as a model for drug permeability experiments.

One of the endogenous pentapeptides with morphine-like activity. It differs from MET-ENKEPHALIN in the LEUCINE at position 5. Its first four amino acid sequence is identical to the tetrapeptide sequence at the N-terminal of BETA-ENDORPHIN.

One of the endogenous pentapeptides with morphine-like activity. It differs from LEU-ENKEPHALIN by the amino acid METHIONINE in position 5. Its first four amino acid sequence is identical to the tetrapeptide sequence at the N-terminal of BETA-ENDORPHIN.

A disulfide opioid pentapeptide that selectively binds to the DELTA OPIOID RECEPTOR. It possesses antinociceptive activity.

A delta-selective opioid (ANALGESICS, OPIOID). It can cause transient depression of mean arterial blood pressure and heart rate.

One of the three major groups of endogenous opioid peptides. They are large peptides derived from the PRO-OPIOMELANOCORTIN precursor. The known members of this group are alpha-, beta-, and gamma-endorphin. The term endorphin is also sometimes used to refer to all opioid peptides, but the narrower sense is used here; OPIOID PEPTIDES is used for the broader group.

A class of opioid receptors recognized by its pharmacological profile. Mu opioid receptors bind, in decreasing order of affinity, endorphins, dynorphins, met-enkephalin, and leu-enkephalin. They have also been shown to be molecular receptors for morphine.

Cell membrane proteins that bind opioids and trigger intracellular changes which influence the behavior of cells. The endogenous ligands for opioid receptors in mammals include three families of peptides, the enkephalins, endorphins, and dynorphins. The receptor classes include mu, delta, and kappa receptors. Sigma receptors bind several psychoactive substances, including certain opioids, but their endogenous ligands are not known.

Strong dependence, both physiological and emotional, upon morphine.

Analogs or derivatives of morphine.

A specific opiate antagonist that has no agonist activity. It is a competitive antagonist at mu, delta, and kappa opioid receptors.

Compounds with activity like OPIATE ALKALOIDS, acting at OPIOID RECEPTORS. Properties include induction of ANALGESIA or NARCOSIS.

A class of opioid receptors recognized by its pharmacological profile. Delta opioid receptors bind endorphins and enkephalins with approximately equal affinity and have less affinity for dynorphins.

A class of cell surface receptors for tachykinins that prefers neurokinin B (neurokinin beta, neuromedin K) over other tachykinins. Neurokinin-3 (NK-3) receptors have been cloned and are members of the G-protein coupled receptor superfamily. They have been found in the central nervous system and in peripheral tissues.

Agents inhibiting the effect of narcotics on the central nervous system.

A mammalian neuropeptide of 10 amino acids that belongs to the tachykinin family. It is similar in structure and action to SUBSTANCE P and NEUROKININ A with the ability to excite neurons, dilate blood vessels, and contract smooth muscles, such as those in the URINARY BLADDER and UTERUS.

A kappa opioid receptor agonist. The compound has analgesic action and shows positive inotropic effects on the electrically stimulated left atrium. It also affects various types of behavior in mammals such as locomotion, rearing, and grooming.

Agents that induce NARCOSIS. Narcotics include agents that cause somnolence or induced sleep (STUPOR); natural or synthetic derivatives of OPIUM or MORPHINE or any substance that has such effects. They are potent inducers of ANALGESIA and OPIOID-RELATED DISORDERS.

An analgesic with mixed narcotic agonist-antagonist properties.

A family of biologically active peptides sharing a common conserved C-terminal sequence, -Phe-X-Gly-Leu-Met-NH2, where X is either an aromatic or a branched aliphatic amino acid. Members of this family have been found in mammals, amphibians, and mollusks. Tachykinins have diverse pharmacological actions in the central nervous system and the cardiovascular, genitourinary, respiratory, and gastrointestinal systems, as well as in glandular tissues. This diversity of activity is due to the existence of three or more subtypes of tachykinin receptors.

Cell surface proteins that bind TACHYKININS with high affinity and trigger intracellular changes influencing the behavior of cells. Three classes of tachykinin receptors have been characterized, the NK-1; NK-2; and NK-3; which prefer, respectively, SUBSTANCE P; NEUROKININ A; and NEUROKININ B.

Progressive diminution of the susceptibility of a human or animal to the effects of a drug, resulting from its continued administration. It should be differentiated from DRUG RESISTANCE wherein an organism, disease, or tissue fails to respond to the intended effectiveness of a chemical or drug. It should also be differentiated from MAXIMUM TOLERATED DOSE and NO-OBSERVED-ADVERSE-EFFECT LEVEL.

A class of opioid receptors recognized by its pharmacological profile. Kappa opioid receptors bind dynorphins with a higher affinity than endorphins which are themselves preferred to enkephalins.

A stable synthetic analog of methionine enkephalin (ENKEPHALIN, METHIONINE). Actions are similar to those of methionine enkephalin. Its effects can be reversed by narcotic antagonists such as naloxone.

An eleven-amino acid neurotransmitter that appears in both the central and peripheral nervous systems. It is involved in transmission of PAIN, causes rapid contractions of the gastrointestinal smooth muscle, and modulates inflammatory and immune responses.

A mammalian neuropeptide of 10 amino acids that belongs to the tachykinin family. It is similar in structure and action to SUBSTANCE P and NEUROKININ B with the ability to excite neurons, dilate blood vessels, and contract smooth muscles, such as those in the BRONCHI.

Derivative of noroxymorphone that is the N-cyclopropylmethyl congener of NALOXONE. It is a narcotic antagonist that is effective orally, longer lasting and more potent than naloxone, and has been proposed for the treatment of heroin addiction. The FDA has approved naltrexone for the treatment of alcohol dependence.

A class of cell surface receptors for tachykinins that prefers neurokinin A; (NKA, substance K, neurokinin alpha, neuromedin L), neuropeptide K; (NPK); or neuropeptide gamma over other tachykinins. Neurokinin-2 (NK-2) receptors have been cloned and are similar to other G-protein coupled receptors.

A class of opioid peptides including dynorphin A, dynorphin B, and smaller fragments of these peptides. Dynorphins prefer kappa-opioid receptors (RECEPTORS, OPIOID, KAPPA) and have been shown to play a role as central nervous system transmitters.

Compounds capable of relieving pain without the loss of CONSCIOUSNESS.

Introduction of therapeutic agents into the spinal region using a needle and syringe.

A transfer RNA which is specific for carrying glycine to sites on the ribosomes in preparation for protein synthesis.

Morphine derivatives of the methanobenzazocine family that act as potent analgesics.

Methods of PAIN relief that may be used with or in place of ANALGESICS.

Scales, questionnaires, tests, and other methods used to assess pain severity and duration in patients or experimental animals to aid in diagnosis, therapy, and physiological studies.

The relationship between the dose of an administered drug and the response of the organism to the drug.

A 31-amino acid peptide that is the C-terminal fragment of BETA-LIPOTROPIN. It acts on OPIOID RECEPTORS and is an analgesic. Its first four amino acids at the N-terminal are identical to the tetrapeptide sequence of METHIONINE ENKEPHALIN and LEUCINE ENKEPHALIN.

The endogenous peptides with opiate-like activity. The three major classes currently recognized are the ENKEPHALINS, the DYNORPHINS, and the ENDORPHINS. Each of these families derives from different precursors, proenkephalin, prodynorphin, and PRO-OPIOMELANOCORTIN, respectively. There are also at least three classes of OPIOID RECEPTORS, but the peptide families do not map to the receptors in a simple way.

Compounds based on benzeneacetamide, that are similar in structure to ACETANILIDES.

A ZINC-containing exopeptidase primarily found in SECRETORY VESICLES of endocrine and neuroendocrine cells. It catalyzes the cleavage of C-terminal ARGININE or LYSINE residues from polypeptides and is active in processing precursors of PEPTIDE HORMONES and other bioactive peptides.

Compounds based on a partially saturated iminoethanophenanthrene, which can be described as ethylimino-bridged benzo-decahydronaphthalenes. They include some of the OPIOIDS found in PAPAVER that are used as ANALGESICS.

A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.

Physiological and psychological symptoms associated with withdrawal from the use of a drug after prolonged administration or habituation. The concept includes withdrawal from smoking or drinking, as well as withdrawal from an administered drug.

A narcotic antagonist similar in action to NALOXONE. It is used to remobilize animals after ETORPHINE neuroleptanalgesia and is considered a specific antagonist to etorphine.

A narcotic analgesic morphinan used as a sedative in veterinary practice.

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.

An unpleasant sensation induced by noxious stimuli which are detected by NERVE ENDINGS of NOCICEPTIVE NEURONS.

Compounds that inhibit or block the activity of NEUROKININ-1 RECEPTORS.

An opioid analgesic related to MORPHINE but with less potent analgesic properties and mild sedative effects. It also acts centrally to suppress cough.

Pain during the period after surgery.

Peptides composed of between two and twelve amino acids.

A non-essential amino acid. It is found primarily in gelatin and silk fibroin and used therapeutically as a nutrient. It is also a fast inhibitory neurotransmitter.

Central gray matter surrounding the CEREBRAL AQUEDUCT in the MESENCEPHALON. Physiologically it is probably involved in RAGE reactions, the LORDOSIS REFLEX; FEEDING responses, bladder tonus, and pain.

A potent narcotic analgesic, abuse of which leads to habituation or addiction. It is primarily a mu-opioid agonist. Fentanyl is also used as an adjunct to general anesthetics, and as an anesthetic for induction and maintenance. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1078)

A class of cell surface receptors for TACHYKININS with a preference for SUBSTANCE P. Neurokinin-1 (NK-1) receptors have been cloned and are members of the G protein coupled receptor superfamily. They are found on many cell types including central and peripheral neurons, smooth muscle cells, acinar cells, endothelial cells, fibroblasts, and immune cells.

A potent inhibitor of membrane metalloendopeptidase (ENKEPHALINASE). Thiorphan potentiates morphine-induced ANALGESIA and attenuates naloxone-precipitated withdrawal symptoms.

A family of hexahydropyridines.

The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.

Protein precursors, also known as proproteins or prohormones, are inactive forms of proteins that undergo post-translational modification, such as cleavage, to produce the active functional protein or peptide hormone.

Injections into the cerebral ventricles.

The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.

Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.

Bluish-colored region in the superior angle of the FOURTH VENTRICLE floor, corresponding to melanin-like pigmented nerve cells which lie lateral to the PERIAQUEDUCTAL GRAY.

Pyrrolidines are saturated, heterocyclic organic compounds containing a five-membered ring with four carbon atoms and one nitrogen atom (NRCH2CH2), commonly found as structural components in various alkaloids and used in the synthesis of pharmaceuticals and other organic materials.

A cylindrical column of tissue that lies within the vertebral canal. It is composed of WHITE MATTER and GRAY MATTER.

The first mixed agonist-antagonist analgesic to be marketed. It is an agonist at the kappa and sigma opioid receptors and has a weak antagonist action at the mu receptor. (From AMA Drug Evaluations Annual, 1991, p97)

The distal and narrowest portion of the SMALL INTESTINE, between the JEJUNUM and the ILEOCECAL VALVE of the LARGE INTESTINE.

Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.

Relief of PAIN, without loss of CONSCIOUSNESS, through ANALGESIC AGENTS administered by the patients. It has been used successfully to control POSTOPERATIVE PAIN, during OBSTETRIC LABOR, after BURNS, and in TERMINAL CARE. The choice of agent, dose, and lockout interval greatly influence effectiveness. The potential for overdose can be minimized by combining small bolus doses with a mandatory interval between successive doses (lockout interval).

A narcotic antagonist with some agonist properties. It is an antagonist at mu opioid receptors and an agonist at kappa opioid receptors. Given alone it produces a broad spectrum of unpleasant effects and it is considered to be clinically obsolete.

Enzyme that is a major constituent of kidney brush-border membranes and is also present to a lesser degree in the brain and other tissues. It preferentially catalyzes cleavage at the amino group of hydrophobic residues of the B-chain of insulin as well as opioid peptides and other biologically active peptides. The enzyme is inhibited primarily by EDTA, phosphoramidon, and thiorphan and is reactivated by zinc. Neprilysin is identical to common acute lymphoblastic leukemia antigen (CALLA Antigen), an important marker in the diagnosis of human acute lymphocytic leukemia. There is no relationship with CALLA PLANT.

Sulfhydryl acylated derivative of GLYCINE.

The inner portion of the adrenal gland. Derived from ECTODERM, adrenal medulla consists mainly of CHROMAFFIN CELLS that produces and stores a number of NEUROTRANSMITTERS, mainly adrenaline (EPINEPHRINE) and NOREPINEPHRINE. The activity of the adrenal medulla is regulated by the SYMPATHETIC NERVOUS SYSTEM.

The observable response an animal makes to any situation.

The rate dynamics in chemical or physical systems.

A 14-amino acid peptide named for its ability to inhibit pituitary GROWTH HORMONE release, also called somatotropin release-inhibiting factor. It is expressed in the central and peripheral nervous systems, the gut, and other organs. SRIF can also inhibit the release of THYROID-STIMULATING HORMONE; PROLACTIN; INSULIN; and GLUCAGON besides acting as a neurotransmitter and neuromodulator. In a number of species including humans, there is an additional form of somatostatin, SRIF-28 with a 14-amino acid extension at the N-terminal.

A narcotic analgesic that may be habit-forming. It is a controlled substance (opium derivative) listed in the U.S. Code of Federal Regulations, Title 21 Parts 329.1, 1308.11 (1987). Sale is forbidden in the United States by Federal statute. (Merck Index, 11th ed)

An opioid analgesic with actions and uses similar to those of MORPHINE, apart from an absence of cough suppressant activity. It is used in the treatment of moderate to severe pain, including pain in obstetrics. It may also be used as an adjunct to anesthesia. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1092)

A non-essential amino acid that occurs in high levels in its free state in plasma. It is produced from pyruvate by transamination. It is involved in sugar and acid metabolism, increases IMMUNITY, and provides energy for muscle tissue, BRAIN, and the CENTRAL NERVOUS SYSTEM.

Amount of stimulation required before the sensation of pain is experienced.

The excretory duct of the testes that carries SPERMATOZOA. It rises from the SCROTUM and joins the SEMINAL VESICLES to form the ejaculatory duct.

An opioid analgesic made from MORPHINE and used mainly as an analgesic. It has a shorter duration of action than morphine.

The most anterior portion of the uveal layer, separating the anterior chamber from the posterior. It consists of two layers - the stroma and the pigmented epithelium. Color of the iris depends on the amount of melanin in the stroma on reflection from the pigmented epithelium.

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.

The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.

The action of a drug that may affect the activity, metabolism, or toxicity of another drug.

A semisynthetic derivative of CODEINE.

Organelles in CHROMAFFIN CELLS located in the adrenal glands and various other organs. These granules are the site of the synthesis, storage, metabolism, and secretion of EPINEPHRINE and NOREPINEPHRINE.

The representation of the phylogenetically oldest part of the corpus striatum called the paleostriatum. It forms the smaller, more medial part of the lentiform nucleus.

A compound produced from succinyl-CoA and GLYCINE as an intermediate in heme synthesis. It is used as a PHOTOCHEMOTHERAPY for actinic KERATOSIS.

Compounds containing the PhCH= radical.

A narcotic used as a pain medication. It appears to be an agonist at kappa opioid receptors and an antagonist or partial agonist at mu opioid receptors.

The interaction of two or more substrates or ligands with the same binding site. The displacement of one by the other is used in quantitative and selective affinity measurements.

Genetically engineered MUTAGENESIS at a specific site in the DNA molecule that introduces a base substitution, or an insertion or deletion.

Striped GRAY MATTER and WHITE MATTER consisting of the NEOSTRIATUM and paleostriatum (GLOBUS PALLIDUS). It is located in front of and lateral to the THALAMUS in each cerebral hemisphere. The gray substance is made up of the CAUDATE NUCLEUS and the lentiform nucleus (the latter consisting of the GLOBUS PALLIDUS and PUTAMEN). The WHITE MATTER is the INTERNAL CAPSULE.

The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.

Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.

One of two ganglionated neural networks which together form the ENTERIC NERVOUS SYSTEM. The myenteric (Auerbach's) plexus is located between the longitudinal and circular muscle layers of the gut. Its neurons project to the circular muscle, to other myenteric ganglia, to submucosal ganglia, or directly to the epithelium, and play an important role in regulating and patterning gut motility. (From FASEB J 1989;3:127-38)

A semisynthetic analgesic used in the study of narcotic receptors.

The naturally occurring or experimentally induced replacement of one or more AMINO ACIDS in a protein with another. If a functionally equivalent amino acid is substituted, the protein may retain wild-type activity. Substitution may also diminish, enhance, or eliminate protein function. Experimentally induced substitution is often used to study enzyme activities and binding site properties.

A narcotic analgesic that can be used for the relief of most types of moderate to severe pain, including postoperative pain and the pain of labor. Prolonged use may lead to dependence of the morphine type; withdrawal symptoms appear more rapidly than with morphine and are of shorter duration.

BENZOIC ACID amides.

Use of electric potential or currents to elicit biological responses.

A drug that is derived from opium, which contains from 0.3-1.5% thebaine depending on its origin. It produces strychnine-like convulsions rather than narcosis. It may be habit-forming and is a controlled substance (opiate) listed in the U.S. Code of Federal Regulations, Title 21 Part 1308.12 (1985). (From Merck Index, 11th ed)

A synthetic opioid that is used as the hydrochloride. It is an opioid analgesic that is primarily a mu-opioid agonist. It has actions and uses similar to those of MORPHINE. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1082-3)

An increased sensation of pain or discomfort produced by mimimally noxious stimuli due to damage to soft tissue containing NOCICEPTORS or injury to a peripheral nerve.

Changes in the amounts of various chemicals (neurotransmitters, receptors, enzymes, and other metabolites) specific to the area of the central nervous system contained within the head. These are monitored over time, during sensory stimulation, or under different disease states.

Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.

Enzymes that act at a free C-terminus of a polypeptide to liberate a single amino acid residue.

Peripheral AFFERENT NEURONS which are sensitive to injuries or pain, usually caused by extreme thermal exposures, mechanical forces, or other noxious stimuli. Their cell bodies reside in the DORSAL ROOT GANGLIA. Their peripheral terminals (NERVE ENDINGS) innervate target tissues and transduce noxious stimuli via axons to the CENTRAL NERVOUS SYSTEM.

Elements of limited time intervals, contributing to particular results or situations.

Substances used for their pharmacological actions on any aspect of neurotransmitter systems. Neurotransmitter agents include agonists, antagonists, degradation inhibitors, uptake inhibitors, depleters, precursors, and modulators of receptor function.

The relief of pain without loss of consciousness through the introduction of an analgesic agent into the epidural space of the vertebral canal. It is differentiated from ANESTHESIA, EPIDURAL which refers to the state of insensitivity to sensation.

The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).

Guanosine 5'-(trihydrogen diphosphate), monoanhydride with phosphorothioic acid. A stable GTP analog which enjoys a variety of physiological actions such as stimulation of guanine nucleotide-binding proteins, phosphoinositide hydrolysis, cyclic AMP accumulation, and activation of specific proto-oncogenes.

The injection of very small amounts of fluid, often with the aid of a microscope and microsyringes.

The parts of a macromolecule that directly participate in its specific combination with another molecule.

A neuropeptide of 29-30 amino acids depending on the species. Galanin is widely distributed throughout the BRAIN; SPINAL CORD; and INTESTINES. There are various subtypes of GALANIN RECEPTORS implicating roles of galanin in regulating FOOD INTAKE; pain perception; memory; and other neuroendocrine functions.

Collection of pleomorphic cells in the caudal part of the anterior horn of the LATERAL VENTRICLE, in the region of the OLFACTORY TUBERCLE, lying between the head of the CAUDATE NUCLEUS and the ANTERIOR PERFORATED SUBSTANCE. It is part of the so-called VENTRAL STRIATUM, a composite structure considered part of the BASAL GANGLIA.

Compounds which inhibit or antagonize biosynthesis or actions of proteases (ENDOPEPTIDASES).

A common neoplasm of early childhood arising from neural crest cells in the sympathetic nervous system, and characterized by diverse clinical behavior, ranging from spontaneous remission to rapid metastatic progression and death. This tumor is the most common intraabdominal malignancy of childhood, but it may also arise from thorax, neck, or rarely occur in the central nervous system. Histologic features include uniform round cells with hyperchromatic nuclei arranged in nests and separated by fibrovascular septa. Neuroblastomas may be associated with the opsoclonus-myoclonus syndrome. (From DeVita et al., Cancer: Principles and Practice of Oncology, 5th ed, pp2099-2101; Curr Opin Oncol 1998 Jan;10(1):43-51)

Dull or sharp aching pain caused by stimulated NOCICEPTORS due to tissue injury, inflammation or diseases. It can be divided into somatic or tissue pain and VISCERAL PAIN.

The air-dried exudate from the unripe seed capsule of the opium poppy, Papaver somniferum, or its variant, P. album. It contains a number of alkaloids, but only a few - MORPHINE; CODEINE; and PAPAVERINE - have clinical significance. Opium has been used as an analgesic, antitussive, antidiarrheal, and antispasmodic.

Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.

A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.

Quantitative determination of receptor (binding) proteins in body fluids or tissue using radioactively labeled binding reagents (e.g., antibodies, intracellular receptors, plasma binders).

A subclass of analgesic agents that typically do not bind to OPIOID RECEPTORS and are not addictive. Many non-narcotic analgesics are offered as NONPRESCRIPTION DRUGS.

The lower portion of the BRAIN STEM. It is inferior to the PONS and anterior to the CEREBELLUM. Medulla oblongata serves as a relay station between the brain and the spinal cord, and contains centers for regulating respiratory, vasomotor, cardiac, and reflex activities.

An opioid analgesic that is used as an adjunct in anesthesia, in balanced anesthesia, and as a primary anesthetic agent.

An opioid analgesic with actions and uses similar to MORPHINE. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1095)

Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.

Gelatinous-appearing material in the dorsal horn of the spinal cord, consisting chiefly of Golgi type II neurons and some larger nerve cells.

Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.

The physical activity of a human or an animal as a behavioral phenomenon.

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.

Forceful administration under the skin of liquid medication, nutrient, or other fluid through a hollow needle piercing the skin.

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.

The action of a drug in promoting or enhancing the effectiveness of another drug.

The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.

Peptides released by NEURONS as intercellular messengers. Many neuropeptides are also hormones released by non-neuronal cells.

An endogenous opioid peptide derived from BETA-LIPOTROPIN of the pro-opiomelanocortin (POMC) system. It is the 16-amino acid sequence of the N-terminal of BETA-ENDORPHIN and differs from GAMMA-ENDORPHIN by one amino acid (beta-endorphin 1-17).