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Neurokinin A
(Substance K)

Clinical Significance:
Neurokinin A is a ten amino acid putative transmitter synthesized in the neurons it is present in.  Neurokinin A is a member of the family called Tachykinins which also include Neurokinin B, Substance P, Physalaemin, and Eledoisin.   Neurokinin A shares 6 of 10 peptide homologies with Neurokinin B even though they are produced by different genes.   Neurokinin A is also very similar in structure to Substance P and produces some of the same biological actions as Substance P.  Neurokinin A is a potent bronchoconstrictor.  In the gut, Neurokinin A is produced by the intrinsic enteric nervous system.

Reference Range:
Up to 40 pg/ml

Procedure:
Neurokinin A is measured by direct radioimmunoassay.

Patient Preparation:
Patient should not be on any medications that affect hypertension, gastrointestinal functions, or pain relievers, if possible, for at least 48 hours prior to collection of specimen.

Specimen Collection:
Collect 10mL blood directly into ISI's Z-tubeTM Preservative and separate as soon as possible. Freeze plasma immediately after separation. Special Z-tubeTM Preservatives are available from ISI. Minimum specimen size is 1mL. Note: one Z-tubeTM may be shared for up to three tests. After centrifuging tube, aliqout 1mL per test in separate vials, mark with name of test and freeze.

Important Precaution:
Specimens for this assay must be collected using the Z-tube. Specimens must be shipped frozen; specimens are not stable at refrigerated or room temperatures. No other specimens are acceptable.

Special Specimens:
For tumor/tissue and various fluids (i.e. CSF, peritoneal, synovial, etc.) contact the Institute for requirements and special handling.

Shipping Instructions:
Ship specimens frozen in dry ice.

References:
1. Mamikunian P, Ardill JES, O'Dorisio TM, et al.Validation of neurokinin A (NKA) assays in the United States and Europe. Pancreas. 2011;40(7):1000-5.
2. Diebold AE, Boudreaux JP, Wang YZ et al. Neurokinin A levels predict survival in patients with well differentiated small bowel neuroendocrine tumors. Surgery. In Press.
3. Kimuro S, Okada M, Sugata Y. Novel neuropeptides neurokinin alpha and beta, isolated from porcine spinal cord. Proc Japan Acad. 1983;59:101.
4. Nawa H, Kotani H, Nakanishi S. Tissue specific generation of tissue pre-pro-tachykinin mRNAs from one gene by alternative RNA splicing. Nature. 1984-5;312(5996):729-34
5. Theodorsson-Norheim E, Norheim I, et alG. Neuropeptide K: a major tachykinin in plasma and tumor tissues from carcinoid patients. Biochem Biophys Res Commun. 1985;131(1):77-83.
6. Conlon JM, Deacon CF, Richter G, et al. Measurement and partial characterization of the multiple forms of neurokinin A-like immunoreactivity in carcinoid tumours. Regul Pept. 1986;Jan;13(2):183-96.
7. Hunt RH, Tougas G. Evolving concepts in functional gastrointestinal disorders: promising directions for novel pharmaceutical treatments. Best Pract Res Clin Gastroenterol. 2002;16(6):869-83.
8. Ardill JE, Erikkson B. The importance of the measurement of circulating markers in patients with neuroendocrine tumours of the pancreas and gut. Endocr Relat Cancer. 2003;10(4):459-62
9. Chen LW, Yung KK, Chan YS. Neurokinin peptides and neurokinin receptors as potential therapeutic intervention targets of basal ganglia in the prevention and treatment of Parkinson's disease. Curr Drug Targets. 2004;5(2):197-206.
10. Severini C, Ciotti MT, Mercanti D, et al. The tachykinin peptide family. Pharmacol Rev.2002;54(2):285-322.
11. Pennefather JN, Lecci A, Candenas ML, et al. Tachykinins and tachykinin receptors: a growing family. Life Sci. 2004;74(12):1445-63.

 

Neurokinin B*

* Test available on a research basis only. Contact ISI for details.

 

Neuropeptide K*

* Test available on a research basis only. Contact ISI for details.

 

Neuropeptide Y

Clinical Significance:
Neuropeptide Y is a 36 amino acid peptide very similar throughout all species of mammals.  It is found primarily in the sympathetic nervous system, gut, and brain.  Neuropeptide Y is closely related structurally to Peptide YY and Vasoactive Intestinal Polypeptide. Neuropeptide Y has key roles in cardiovascular and hypothalamic function.  It potentiates vasoconstriction, causing an increase in blood pressure. Levels are increased by stress, Dexamethasone, septic shock, relaxation of colon, Atrial Natriuretic Factor, water and sodium secretion, Luteinizing Hormone and ACTH.  Levels are inhibited by amphetamines, and are decreased in patients with Alzheimer's disease.  Neuropeptide Y inhibits Norepinephrine, the effect of Cholecystokinin, Renin release, Insulin and Glucagon secretion, and the Melanotropins.  Actions of Neuropeptide Y are enhanced by a2 adrenoreceptor agonists.

Reference Range:
By report.

Procedure:
Neuropeptide Y is measured by direct radioimmunoassay.

Patient Preparation:
Patient should be fasting 10 - 12 hours prior to collection of specimen.  Medications that affect Insulin secretion or gastrointestinal function should be discontinued, if possible, for at least 48 hours prior to collection

Specimen Collection:
Collect 10 mL EDTA plasma in special tube containing the Z-tube and separate as soon as possible. Freeze plasma immediately after separation. Special Z-tube (is available from Inter Science Institute (ISI). Minimum specimen size is 1 ml.

Important Precaution:
Specimens for this assay must be collected using the Z-tube. Specimens must be shipped frozen; specimens are not stable at refrigerated or room temperatures. No other specimens are acceptable.

Special Specimens:
For tumor/tissue and various fluids (i.e. CSF, peritoneal, synovial, etc.) contact the Institute for requirements and special handling.

Shipping Instructions:
Ship specimens frozen in dry ice.

References:
1. H Jamal, PM Jones, J Byrne, K Suda, MA Ghatei, SM Kanse, and SR Bloom.  Peptide Contents of NeuropeptideY, Vasoactive Intestinal Polypeptide, and b-Calcitonin Gene-Related Peptide and Their Messenger Ribonucleic Acids after Dexamethasone Treatment in the Isolated Rat Islets of Langerhans.  Endocrinology 129: 3372-3380, 1991.

2. J Lehmann.  Neuropeptide Y:  An Overview.  Drug Development Research 19: 329-351, 1989.

 

Neurotensin

Clinical Significance:
Neurotensin is a 13 amino acid peptide produced primarily by endocrine cells of the ileal mucosa.  Physiological actions of Neurotensin include hypertension, vasodilation, hyperglycemia, and inhibition of gastric motility.  Its C-terminus is similar to Angiotensin I.  It is a potent analgesic affecting hypothermia, muscle relaxation, and decreased motor activity.  Pancreatic Polypeptide secretion is strongly stimulated by Neurotensin.  Neurotensin appears to cause the release of Luteinizing Hormone-Releasing Hormone and Corticotropin Releasing Hormone effecting the release of Luteinizing Hormone, Follicle Stimulating Hormone, and ACTH but not Thyroid Stimulating Hormone or Growth Hormone.  Neurotensin also stimulates pancreatic bicarbonate and intestinal secretion.  Neurotensin levels are stimulated by food and Bombesin.  Elevated levels have been found in pancreatic endocrine tumors, Oat Cell, Squamous Cell, and Adeno Carcinomas.  Elevated levels have been found to cause watery diarrhea.

Reference Range:
50 - 100 pg/ml

Procedure:
Neurotensin is measured by direct radioimmunoassay.

Patient Preparation:
Patient should be fasting 10 - 12 hours prior to collecton of specimen.  Patient should not be on any antacid medication or medications that affect gastroentero-intestinal function, if possible, for at least 48 hours prior to collection.

Specimen Collection:
Collect 10 mL EDTA plasma in special tube containing the Z-tube and separate as soon as possible. Freeze plasma immediately after separation. Special Z-tube is available from Inter Science Institute (ISI). Minimum specimen size is 1 ml.

Important Precaution:
Specimens for this assay must be collected using the Z-tube. Specimens must be shipped frozen; specimens are not stable at refrigerated or room temperatures. No other specimens are acceptable.

Special Specimens:
For tumor/tissue and various fluids (i.e. CSF, peritoneal, synovial, etc.) contact the Institute for requirements and special handling.

Shipping Instructions:
Ship specimens frozen in dry ice.

References:
1. A Schulkes, P Chick, H Wong, and JH Walsh.  A Radioimmunoassay for Neurotensin in Human Plasma.  Clinica Chimica Acta 125:  49, 1982.

2. RE Carraway, SP Mitra, GE Feurle, and NH Hickey.  Presence of Neurotensin and Neuromedin N within a Common Precursor from a Human Pancreatic Neuroendocrine Tumor.  Journal of Clinical Endocrinology and Metabolism  66: 1323, 1988.

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