Atrophy 712319 225165533 2008-07-12T06:27:44Z 85.3.181.242 /* See also */ {{Cleanup|date=June 2008}} {{dablink|For the American thrash metal band, see [[Atrophy (band)]]}} '''Atrophy''' is the partial or complete [[wasting]] away of a part of the [[body]]. Causes of atrophy include poor [[nourishment]], poor [[circulatory system|circulation]], loss of [[hormone|hormonal]] support, loss of [[nerve]] supply to the target [[Organ (anatomy)|organ]], disuse or lack of [[exercise]] or disease intrinsic to the tissue itself. Hormonal and nerve inputs that maintain an organ or body part are referred to as ''trophic''. Atrophy is a general [[physiological]] process of reabsorption and breakdown of [[biological tissue|tissues]], involving [[apoptosis]] on a [[cell (biology)|cell]]ular level. When it occurs as a result of [[disease]] or loss of trophic support due to other disease, it is termed ''pathological atrophy'', although it can be a part of normal body development and [[homeostasis]] as well. == Atrophy examples == === Normal development === Examples of atrophy as part of normal development include shrinkage and involution of the [[thymus]] in early childhood and the [[tonsils]] in adolescence. ===Breast atrophies=== Atrophy of the [[breast]]s can occur with prolonged [[estrogen]] reduction, as with [[anorexia nervosa]] or [[menopause]]. Atrophy of the testes occurs with prolonged use of enough exogenous [[sex steroid]] (either [[androgen]] or [[estrogen]]) to reduce [[gonadotropin]] secretion. The [[adrenal gland]]s atrophy during prolonged use of exogenous [[glucocorticoid]]s like [[prednisone]]. ===Muscle atrophies=== {{main|Muscle atrophy}} ''Disuse atrophy'' of [[muscle]]s ([[muscle atrophy]]) and [[bone]]s, with loss of mass and strength, can occur after prolonged immobility, such as extended [[bedrest]], or having a body part in a cast (living in darkness for the eye, bedridden for the legs etc.). This type of atrophy can usually be reversed with exercise unless severe. Astronauts must exercise regularly to minimize atrophy of their limb muscles while they are in microgravity. There are many diseases and conditions which cause atrophy of muscle mass. For example diseases such as cancer and AIDS induce a body wasting syndrome called "[[cachexia]]", which is notable for the severe [[muscle atrophy]] seen. Other syndromes or conditions which can induce skeletal [[muscle atrophy]] are [[congestive heart failure]] and liver disease. During aging, there is a gradual decrease in the ability to maintain skeletal muscle function and mass. This condition is called "[[sarcopenia]]", and may be distinct from atrophy in its pathophysiology. While the exact cause of sarcopenia is unknown, it may be induced by a combination of a gradual failure in the "[[satellite cells]]" which help to regenerate skeletal muscle fibers, and a decrease in sensitivity to or the availability of critical secreted growth factors which are necessary to maintain muscle mass and satellite cell survival.<ref>{{cite web | url = http://www.nlm.nih.gov/medlineplus/ency/article/003188.htm | title = Muscle atrophy | publisher= [[MedlinePlus]] | accessdate = 2007-10-02 | date = 2007-05-22 | last = Campellone | first = Joseph V. | format = html | language = english}}</ref> === Dystrophies, myosities, and motor neuron conditions === Pathologic atrophy of muscles can occur due to diseases of the motor nerves, or due to diseases of the muscle tissue itself. Examples of atrophying nerve diseases include CMT (Charcot Marie Tooth syndrome) [[poliomyelitis]], [[amyotrophic lateral sclerosis]] (ALS or Lou Gehrig's disease), and [[Guillain-Barre syndrome]]. Examples of atrophying muscle diseases include [[muscular dystrophy]], [[myotonia congenita]], and [[myotonic dystrophy]]. ===Vaginal atrophies=== In post-menopausal women, the walls of the vagina atrophy and become thinner. The mechanism for the age-related condition is not yet clear, though there are theories that the effect is caused by decreases in estrogen levels.<ref>{{cite web | url = http://medicine.science-tips.org/health/diseases-and-conditions/types-of-atrophy.html | title = Types of Atrophy | accessdate = 2007-10-02 | format = html | language = english}}</ref> ==Research== It has been reported that [[Astemizole]] might prevent 97% of the muscle wasting that occurs in immobile, bedridden patients.<ref name="ND2006">{{cite news | url=http://www2.netdoctor.co.uk/news/index.asp?y=2006&m=5&d=25&id=123026 |title = Drug could stop muscle wasting' |publisher = NetDoctor.co.uk |date = 2006-05-25 |accessdate = 2006-05-27}}</ref> Testing upon mice showed that it blocked the activity of a protein present in the muscle that is involved in muscle atrophy.<ref name="FASEBJ2006-Wang">{{cite journal | author=Wang X, Hockerman GH, Green Iii HW, Babbs CF, Mohammad SI, Gerrard D, Latour MA, London B, Hannon KM, Pond AL | title=Merg1a K+ channel induces skeletal muscle atrophy by activating the ubiquitin proteasome pathway | journal=FASEB J | year=2006 | month=May24 | pmid=16723379 | volume=20 | pages=1531 | doi=10.1096/fj.05-5350fje}}</ref> However the concerns for the drug's longterm effects on the heart preclude its routine use in humans for this indication, and further alternative drugs are being sought.<ref name="ND2006" /> ==See also== *[[Olivopontocerebellar atrophy]] *[[Optic atrophy]] *[[Spinomuscular atrophy]] *[[Testicular atrophy]] *[[Hypertrophy]] ==References== {{reflist}} [[Category:Gross pathology]] [[bg:Атрофия]] [[da:Atrofi]] [[de:Atrophie]] [[es:Atrofia]] [[eo:Atrofio]] [[fr:Atrophie]] [[it:Atrofia]] [[lt:Atrofija]] [[nl:Atrofie]] [[ja:萎縮]] [[no:Atrofi]] [[pl:Atrofia]] [[pt:Atrofia]] [[ru:Атрофия]] [[sv:Atrofi]] [[uk:Атрофія]]