Purpose | This immunoassay kit allows for the specific measurement of Human Orexin A concentrations in cell culture supernates, serum and plasma. |
Sample Type | Cell Culture Supernatant, Serum, Plasma |
Analytical Method | Quantitative |
Detection Method | Colorimetric |
Specificity | This assay recognizes recombinant and natural Human Orexin A. |
Characteristics | Homo sapiens,Human,Orexin,Hypocretin,Hcrt,HCRT,OX,PPORX,PPOX |
Components | Reagent (Quantity): Assay plate (1), Standard (2), Sample Diluent (1x20ml), Assay Diluent A (1x10ml), Assay Diluent B (1x10ml), Detection Reagent A (1x120μl), Detection Reagent B (1x120μl), Wash Buffer(25 x concentrate) (1x30ml), Substrate (1x10ml), Stop Solution (1x10ml) |
Alternative Name | HCRT (OX ELISA Kit Abstract) |
Background | Orexins, also called hypocretins, are the common names given to a pair of highly excitatory neuropeptide hormones that were simultaneously discovered by two groups of researchers in rat brains.The two related peptides (orexin A and B, or hypocretin-1 and -2), with approximately 50% sequence identity, are produced by cleavage of a single precursor protein. Studies suggest that orexin A/hypocretin-1 may be of greater biological importance than orexin B/hypocretin-2. Although these peptides are produced by a very small population of cells in the lateral and posterior hypothalamus, they send projections throughout the brain. Orexin A peptide is 100% conserved between human, mouse, rat, canine, with BSA bovinew and porcine.The orexins/hypocretins are strongly conserved peptides, found in all major classes of vertebrates. The peptides are thought to have arisen early in vertebrate evolution.The orexin/hypocretin system was initially suggested to be primarily involved in the stimulation of food intake, based on the finding that central administration of orexin A/hypocretin-1 increases food intake. The discovery that orexin/hypocretin dysregulation causes the sleep disorder narcolepsy subsequently indicated a major role for this system in sleep regulation. Leptin is a hormone produced by fat cells and acts as a long-term internal measure of energy state. Ghrelin is a short term factor secreted by the stomach just before an expected meal, and strongly promotes food intake.Orexin-producing cells have recently been shown to be inhibited by glucose but are activated by ghrelin. Hypocretin-producing cells have recently been shown to be inhibited by leptin (by leptin receptors) but are activated by ghrelin and hypoglycemia. Orexin/hypocretin (as of 2007) is therefore a very important link between metabolism and sleep regulation. Such a relationship has been long suspected based on the observation that long-term sleep deprivation in rodents dramatically increases food intake and energy metabolism, i.e. catabolism, with lethal consequences on a long term basis. |
Pathways | Synaptic Membrane, Feeding Behaviour |
Sample Volume | 100 μL |
Plate | Pre-coated |
Protocol | This assay employs the quantitative sandwich enzyme immunoassay technique. A monoclonal antibody specific for Orexin A has been pre-coated onto a microplate. Standards and samples are 2 pipetted into the wells and any Orexin A present is bound by the immobilized antibody. An enzyme-linked polyclonal antibody specific for Orexin A is added to the wells. Following a wash to remove any unbound antibody-enzyme reagent, a substrate solution is added to the wells and color develops in proportion to the amount of Orexin A bound in the initial step. The color development is stopped and the intensity of the color is measured. |
Reagent Preparation |
3 Bring all reagents to room temperature before use. Wash Buffer - If crystals have formed in the concentrate, warm to room temperature and mix gently until the crystals have completely dissolved. Dilute 20 mL of Wash Buffer Concentrate into deionized or distilled water to prepare 500 ml of Wash Buffer. Standard - Reconstitute the Standard with 1.0 mL of Sample Diluent. This reconstitution produces a stock solution of 1000 pg/ml. Allow the standard to sit for a minimum of 15 minutes with gentle agitation prior to making serial dilutions. The undiluted standard serves as the high standard (1000 pg/ml). The Sample Diluent serves as the zero standard (0 pg/ml). Detection Reagent A and B - Dilute to the working concentration specified on the vial label using Assay Diluent A and B (1:100), respectively. |
Sample Collection | Cell culture supernates - Remove particulates by centrifugation and assay immediately or aliquot and store samples at ≤ -20 °C. Avoid repeated freeze-thaw cycles. Serum - Use a serum separator tube (SST) and allow samples to clot for 30 minutes before centrifugation for 15 minutes at approximately 1000 x g. Remove serum and assay immediately or aliquot and store samples at -20 °C. Plasma - Collect plasma using EDTA or heparin as an anticoagulant. Centrifuge samples for 15 minutes at 1000 x g at 2 - 8 °C within 30 minutes of collection. Store samples at ≤ -20 °C. Avoid repeated freeze-thaw cycles. Note: Citrate plasma has not been validated for use in this assay. |
Assay Procedure |
Allow all reagents to reach room temperature. Arrange and label required number of strips. |
Calculation of Results |
Average the duplicate readings for each standard, control, and sample and subtract the average zero standard optical density. Create a standard curve by reducing the data using computer software capable of generating a four parameter logistic (4-PL) curve-fit. As an alternative, construct a standard curve by plotting the mean absorbance for each standard on the y-axis against the concentration on the x-axis and draw a best fit curve through the points on the graph. The data may be linearized by plotting the log of the Orexin A concentrations versus the log of the O.D. and the best fit line can be determined by regression analysis. This procedure will produce an adequate but less precise fit of the data. If samples have been diluted, the concentration read from the standard curve must be multiplied by the dilution factor. |
Restrictions | For Research Use only |
Handling Advice |
1. The kit should not be used beyond the expiration date on the kit label. 2. Do not mix or substitute reagents with those from other lots or sources. 3. If samples generate values higher than the highest standard, further dilute the samples with the Assay Diluent and repeat the assay. Any variation in standard diluent, operator, pipetting technique, washing technique,incubation time or temperature, and kit age can cause variation in binding. 4. This assay is designed to eliminate interference by soluble receptors, ligands, binding proteins, and other factors present in biological samples. Until all factors have been tested in the Immunoassay, the possibility of interference cannot be excluded. |
Storage | 4 °C/-20 °C |
Storage Comment | The Standard, Detection Reagent A, Detection Reagent B and the 96-well strip plate should be stored at -20 °C upon being received. The other reagents can be stored at 4 °C. |