Sensitization

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Sensitization ( English sensitization ) refers to the increase in the strength of a response upon repeated presentation of the same stimulus . The sensitization has been proven in a number of laboratory tests . For example, cats show an increasingly stronger motor response when a short electrical shock is repeatedly applied to one of their limbs.

The opposite process of a decrease in reaction strength is habituation .

Evolutionary background

If a repeated stimulus proves to be significant, it is advantageous to react to it particularly quickly or with increased attention. Examples are the voice of one's own offspring or the telltale sounds of hostile creatures. Pain is intensified so that the underlying cause is noticed and avoided as quickly as possible. It is in the sensitization so to learning processes that serve primarily the alarm in case of danger or special opportunities. However, this process is prone to failure in that the alarming reinforcement can overshoot its target and get out of control.

Mechanisms

The neuronal and biochemical mechanisms of sensitization are diverse. There are differences here both between the locations of sensitization (e.g. pain receptor , reward center , etc.) and within such a location.

Pain amplification

In the sensitization of pain sensations , there are mechanisms (1) of increased excitability of the membrane of the pain receptor cell , (2) an increased nervous ( synaptic ) transmission from other cells to that cell, and (3) a reduced inhibitory ( inhibitory ) effect on this cell . All these mechanisms are triggered by (increased) previous excitation (learning effects), inflammation or injuries and are thus an expression of the adaptability of nervous systems ( neuronal plasticity ).

Addiction and relapse risk

Addictive behavior of all kinds has as a biological basis the sensitization of the reward system in the brain, the mesolimbic system . A few stimuli - from drugs, gambling, etc. - can make this system over-sensitive for a long time and trigger addictive desire. It is of considerable importance that this sensitization only affects the desire. In contrast to the desire, the desired feeling ( euphoria ) is not increased, but rather weakens (development of tolerance ). The sensitization usually lasts long after withdrawal and therefore increases the risk of relapse.

Cross sensitization

The term cross-sensitization encompasses the mutual sensitization of neighboring nervous systems or organs, e.g. B. in the lower pelvic area , as well as the sensitization of a nervous system to other - closely or distantly related - stimuli. The latter includes, for example, the sensitization of the reward system in the brain through legal drugs - such as nicotine and alcohol - also for illegal drugs, for various illegal drugs among each other, and for drugs caused by food addiction including sugar addiction .

Medical importance

Sensitization is an important contributing factor in a large number of health disorders and diseases. As a rule, this is an amplification of a disorder, although the extent of the amplification is difficult or impossible to estimate. In some cases it seems to be possible that only the intensification of the disorder will make it a burden for those affected. Examples are phantom noises ( tinnitus ), loud hearing ( hyperacusis ), overactive bladder , pain syndrome fibromyalgia , and chronic fatigue syndrome .

See also

literature

  • AK Johnson, Z. Zhang, SC Clayton, TG Beltz, SW Hurley, RL Thunhorst, B. Xue: The roles of sensitization and neuroplasticity in the long-term regulation of blood pressure and hypertension. In: American Journal of Physiology - Regulatory, Integrative and Comparative Physiology. Volume 309, Number 11, December 2015, pp. R1309 – R1325, doi: 10.1152 / ajpregu.00037.2015 . PMID 26290101 , PMC 4698407 (free full text) (review).
  • X. Belda, S. Fuentes, N. Daviu, R. Nadal, A. Armario: Stress-induced sensitization: the hypothalamic-pituitary-adrenal axis and beyond. In: Stress. Volume 18, number 3, 2015, pp. 269-279, doi: 10.3109 / 10253890.2015.1067678 . PMID 26300109 (Review), (PDF)
  • LJMJ Vanderschuren, RC Pierce: Sensitization Processes in Drug Addiction. In: D. Self, J. Staley Gottschalk (Ed.): Behavioral Neuroscience of Drug Addiction. (= Current Topics in Behavioral Neurosciences. Volume 3). Springer, Berlin 2010, ISBN 978-3-642-03001-7 , pp. 179–195, (preview Google Books) .
  • Henrik Walter , Markus Barth: Functional imaging in psychiatry and psychotherapy: methodological principles and clinical applications . Schattauer Verlag, Stuttgart 2005, p. 214 f. (on-line)
  • Gerhard founder, Otto Benkert (ed.): Manual of psychopharmacotherapy . Springer-Verlag, Berlin 2012, Section 29.3: Sensitization. Pp. 288-292, ISBN 978-3-642-19844-1 , (online) .

Web links

Individual evidence

  1. ↑ Eberhard Biesinger, Heinrich Iro (Ed.): Tinnitus. Springer-Verlag, Heidelberg 2005, ISBN 3-540-27491-X , p. 93f, (preview Google Books) .
  2. ↑ A. Latremoliere, CJ Woolf: Central sensitization: a generator of pain hypersensitivity by central neural plasticity. In: The journal of pain: official journal of the American Pain Society. Volume 10, Number 9, September 2009, pp. 895-926, doi: 10.1016 / j.jpain.2009.06.012 . PMID 19712899 , PMC 2750819 (free full text) (review).
  3. ↑ JD Steketee, PW Kalivas: Drug wanting: behavioral sensitization and relapse to drug-seeking behavior. In: Pharmacological reviews. Volume 63, number 2, June 2011, pp. 348-365, doi: 10.1124 / pr.109.001933 . PMID 21490129 , PMC 3082449 (free full text) (review).
  4. ^ MJ Robinson, AM Fischer, A. Ahuja, EN Lesser, H. Maniates: Roles of "Wanting" and "Liking" in Motivating Behavior: Gambling, Food, and Drug Addictions. In: Current topics in behavioral neurosciences. Volume 27, 2016, pp. 105-136, doi : 10.1007 / 7854_2015_387 . PMID 26407959 (Review), (PDF)
  5. ↑ PR Brumovský, GF Gebhart: Visceral organ cross-sensitization - perspective on integrated. In: Autonomic neuroscience: basic & clinical. Volume 153, number 1–2, February 2010, pp. 106–115, doi: 10.1016 / j.autneu.2009.07.006 . PMID 19679518 , PMC 2818077 (free full text) (review).
  6. ↑ AP Malykhina, JJ Wyndaele, KE Andersson, S. De Wachter, RR Dmochowski: Do the urinary bladder and large bowel interact, in sickness or in health? ICI-RS 2011. In: Neurourology and urodynamics. Volume 31, number 3, March 2012, pp. 352-358, doi: 10.1002 / nau.21228 . PMID 22378593 , PMC 3309116 (free full text) (review).
  7. ↑ AR Burke, KA Miczek: Stress in adolescence and drugs of abuse in rodent models: role of dopamine, CRF, and HPA axis. In: Psychopharmacology. Volume 231, Number 8, April 2014, pp. 1557-1580, doi: 10.1007 / s00213-013-3369-1 . PMID 24370534 , PMC 3969449 (free full text) (review).
  8. ↑ KJ Steffen, SG Engel, JA Wonderlich, GA Pollert, C. Sondag: Alcohol and Other Addictive Disorders Following Bariatric Surgery: Prevalence, Risk Factors and Possible Etiologies. In: European eating disorders review: the journal of the Eating Disorders Association. Volume 23, Number 6, November 2015, pp. 442–450, doi: 10.1002 / erv.2399 . PMID 26449524 (Review), (PDF)
  9. ↑ NM Avena, P. Rada, BG Hoebel: Evidence for sugar addiction: behavioral and neurochemical effects of intermittent, excessive sugar intake. In: Neuroscience and biobehavioral reviews. Volume 32, number 1, 2008, pp. 20-39, doi: 10.1016 / j.neubiorev.2007.04.019 . PMID 17617461 , PMC 2235907 (free full text) (review).
  10. ↑ HP Zenner, M. Pfister, N. Birbaumer: Tinnitus sensitization: Sensory and psychophysiological aspects of a new pathway of acquired centralization of chronic tinnitus. In: Otology & neurotology: official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology. Volume 27, Number 8, December 2006, pp. 1054-1063, doi: 10.1097 / 01.mao.0000231604.64079.77 . PMID 17130796 (Review).
  11. ↑ RS Tyler, M. Pienkowski, ER Roncancio, HJ Jun, T. Brozoski, N. Dauman, N. Dauman, G. Andersson, AJ Keiner, AT Cacace, N. Martin, BC Moore: A review of hyperacusis and future directions : part I. Definitions and manifestations. In: American journal of audiology. Volume 23, number 4, December 2014, pp. 402-419, doi : 10.1044 / 2014_AJA-14-0010 . PMID 25104073 (Review), (PDF)
  12. ^ WS Reynolds, R. Dmochowski, A. Wein, S. Bruehl: Does central sensitization help explain idiopathic overactive bladder? In: Nature reviews. Urology. Volume 13, Number 8, 08 2016, pp. 481–491, doi: 10.1038 / nrurol.2016.95 . PMID 27245505 , PMC 4969200 (free full text) (review).
  13. ↑ KC Fleming, MM Volcheck: Central sensitization syndrome and the initial evaluation of a patient with fibromyalgia: a review. In: Rambam Maimonides medical journal. Volume 6, number 2, April 2015, p. E0020, doi: 10.5041 / RMMJ.10204 . PMID 25973272 , PMC 4422459 (free full text) (review).
  14. ↑ J. Nijs, M. Meeus, J. Van Oosterwijck, K. Ickmans, G. Moorkens, G. Hans, LS De Clerck: In the mind or in the brain? Scientific evidence for central sensitization in chronic fatigue syndrome. In: European journal of clinical investigation. Volume 42, Number 2, February 2012, pp. 203-212, doi: 10.1111 / j.1365-2362.2011.02575.x . PMID 21793823 (Review), (PDF)