Non-tropic hormone

Non-tropic hormones are hormones that directly stimulate target cells to induce effects. This differs from the tropic hormones, which act on another endocrine gland. Non-tropic hormones are those that act directly on targeted tissues or cells, and not on other endocrine gland to stimulate release of other hormones. Many hormones act in a chain reaction. Tropic hormones usually act in the beginning of the reaction stimulating other endocrine gland to eventually release non-tropic hormones. These are the ones that act in the end of the chain reaction on other cells that are not part of other endocrine gland. The Hypothalamic-pituitary-adrenal axis is a perfect example of this chain reaction. The reaction begins in the hypothalamus with a release of corticotropin-releasing hormone/factor (CRH/F; tropic). This stimulates the anterior pituitary and causes it to release Adrenocorticotropic hormone (ACTH; tropic) to the adrenal glands. Lastly, cortisol (non-tropic) is secreted from the adrenal glands and goes into the bloodstream where it can have more widespread effects on organs and tissues. Since cortisol is what finally reaches other tissues in the body, it is a non-tropic hormone. CRH an ACTH are tropic hormones because they act on the anterior pituitary gland and adrenal glands, respectively, both of which are endocrine glands.[1] Non-tropic hormones are thus often the last piece of a larger process and chain of hormone secretion. Both tropic and non-tropic hormones are necessary for proper endocrine function. For example, if ACTH (Adrenocorticotropin hormone; a tropic hormone) is inhibited, cortisol can no longer be released because the chain reaction has been interrupted.[2] Some examples of non-tropic hormones are:

Most endocrine glands, such as the gonads, pancreas, and adrenal glands, produce non-tropic hormones. Those released from the pituitary gland in the brain include:[10]

See also

References

  1. Nelson, Randy (2011). An Introduction to Behavioral Endocrinology. Sunderland, MA: Sinauer Associates Inc.
  2. Grinspoon, S.K.; B.M.K Biller (1994). "Laboratory assessment of adrenal insufficiency". Journal of Clinical Endocrinology and Metabolism. 79 (4): 923–931. doi:10.1210/jc.79.4.923.
  3. Stavisky, Ronda; Fillipo Aureli; Elizabeth Russel (1998). "Response of fecal cortisol to stress in captive chimpanzees (Pan troglodytes)". American Journal of Primatology. 44 (1): 57–69. doi:10.1002/(sici)1098-2345(1998)44:1<57::aid-ajp5>3.3.co;2-6.
  4. De Quervain, D.J.F.; B. Roozendaal; J.L. McGaugh (1998). "Stress and glucocorticoids impair retrieval of long-term spatial memory". Nature. 394 (6695): 787–790. doi:10.1038/29542. PMID 9723618.
  5. Nielsen, S.; Chou, C.L.; Marples, D.; Christiensen, E.I.; Kishore, B.K.; Knepper, M.A. (1995). "Vasopressin increases water permeability of kidney collecting duct by inducing translocation of aquaporin-CD water channels to plasma membrane.". Proceedings of the National Academy of Sciences of the United States of America. 92 (4): 1013–1017. doi:10.1073/pnas.92.4.1013. PMC 42627Freely accessible. PMID 7532304.
  6. Miles-Richardson, S.R.; Pierens, S.L.; Nichols, K.M.; Kramer, V.J.; Snyder, E.M.; Snyder, S.A.; Render, J.A.; Fitzgerald, S.D.; Giesy, J.P. (1999). "Effects of Waterborne Exposure to 4-Nonylphenol and Nonylphenol Ethoxylate on Secondary Sex Characteristics and Gonads of Fathead Minnows (Pimephales promelas)". Environmental Research. 80 (2): S122-S137. doi:10.1006/enrs.1998.3945.
  7. Tremblay, Richard E. (1998). "Testosterone, Physical Aggression, Dominance, and Physical Development in Early Adolescence.". International Journal of Behavioral Development. 22 (4): 753–777. doi:10.1080/016502598384153.
  8. Husslein, P.; Fuchs, A.R.; Fuchs, F. (1981). "Oxytocin and the initiation of human parturition. I. Prostaglandin release during induction of labor by oxytocin". American Journal of Obstetric Gynecology. 141 (6): 688–693.
  9. Dimsdale, Joel E.; Jonathan Moss (1980). "Plasma Catecholamines in Stress and Exercise.". Journal of the American Medical Association. 243 (4): 340–342. doi:10.1001/jama.1980.03300300018017.
  10. Cambell, Neil A.; Jane B. Reece. Biology (6th ed.). Sinauer Associates. ISBN 0-321-27045-2.

Sources

External links

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