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The phenomenon of male lactation in humans has become more common in recent years due to the use of medications that stimulate (often by inhibiting dopamine) a man's mammary glands. The increasing presence of xenoestrogens may also play a role, interfering with the hormonal system of males. In ordinary circumstances, there is so little mammary tissue that it is unnoticeable; if the male breasts develop visibly, the condition is called gynecomastia.

Though the mammary glands of human males cannot produce milk automatically under natural conditions, with appropriate hormonal stimulus—mimicking that which human females produce naturally when they become pregnant and give birth—they can.[1]

Newborn baby boys (and girls) can occasionally produce milk because of the intense hormones involved in their mother's pregnancy and the hours of childbirth; this is called witch's milk. Male lactation can also come about via the use of a physical stimulus, like that used in the process of induced lactation. That is, if the male breast is suckled, or pumped enough, lactation will occur as a result.

Male lactation was of some interest to Charles Darwin, who commented on it in The Descent of Man, and Selection in Relation to Sex (1871):

"It is well known that in the males of all mammals, including man, rudimentary mammae exist. These in several instances have become well developed, and have yielded a copious supply of milk. Their essential identity in the two sexes is likewise shewn by their occasional sympathetic enlargement in both during an attack of the measles."[2]

Darwin later considered the nearly perfect function of male nipples in contrast to greatly reduced structures such as the vesicula prostatica, speculating that both sexes may have nursed young in early mammalian ancestors, and subsequently mammals evolved to inactivate them in males at an early age.[3]

Non-Human Animal Male Lactation

The phenomenon of male lactation occurs in some other species, notably the Dayak fruit bat (Dyacopterus spadiceus), and the lactating males may assist in the nursing of their infants. In addition, male goats are known to lactate on occasion.[4]

Human Male Lactation

Male lactation is a side effect that may be caused by hormonal treatments given to men suffering from prostate cancer, or drugs that block dopamine receptors. Female hormones are used to slow the production of cancerous prostate tissue, but these same hormones also stimulate the mammary glands.

Male-to-female transsexuals may also produce milk owing to the hormones they take to reshape their bodies.

Male lactation can be a side effect of antipsychotic medication.

Extreme stress combined with demanding physical activity and a shortage of food has also been known to cause male lactation. The phenomenon occurred in survivors of the liberated Nazi concentration camps after World War II.[1] Some American POWs returning from the Korean and Vietnam Wars also experienced male lactation.

The phenomenon has also been observed in isolated cases in other parts of the world.[5]

In Why Is Sex Fun?, Jared Diamond reports of male and female cancer patients being treated with estrogen who proceeded to lactate when injected with prolactin, and suggests that mechanical stimulation of male breasts, by releasing prolactin, could result in lactation.[6]

Cases have been reported of men breast-feeding babies.[1]

Treatment

If desired, discontinuing the offending drug will stop male lactation. If it does not resolve, a combination of a dopamine agonist such as cabergoline or bromocriptine in combination with a SERM such as tamoxifen (often combined with an aromatase inhibitor), in difficult cases dihydrotestosterone may be necessary, applied locally.

Treatment will stop progress but resolution takes months to years. Surgery is available in resistant cases but relapse can occur if not controlled.[7]

See also

References

Notes

  1. ^ a b Jared Diamond (February 1995). "Father's milk - male mammals' potential for lactation". Discover. http://discovermagazine.com/1995/feb/fathersmilk468. 
  2. ^ Descent of Man, Chapter I
  3. ^ Descent of Man, Chapter VI
  4. ^ Gómez MA, Garcés-Abadías B, Muñoz A, Vásquez F, Serrano J, Bernabé A (1999). "Structural and Ultrastructural Study of GH, PRL and SMT Cells in Male Goat by Immunocytochemical Methods". Cells Tissues Organs 165: 22–29. doi:10.1159/000016670. 
  5. ^ Nikhil Swaminathan (2007-09-06). "Strange but True: Males Can Lactate". Scientific American. http://www.sciam.com/article.cfm?id=strange-but-true-males-can-lactate&sc=rss. Retrieved 2008-05-27. 
  6. ^ Jared Diamond (2006). Why is Sex Fun? The Evolution of Human Sexuality. New York: Basic Books. ISBN 0-465-03126-9. 
  7. ^ Ronald S. Swerdloff, MD, Jason Ng, MD, and Gladys E. Palomeno, MD (2004-03-01). Gynecomastia: Etiology, Diagnosis, and Treatment. http://www.endotext.org/male/male14/male14.html. Retrieved 2009-08-03. 

Sources

  • Angier, Natalie; New York Times, February 24, 1994. Cr. J. Covey.
  • Francis, Charles M., et al.; "Lactation in Male Fruit Bats," Nature, 367:691, 1994.
  • Fackelmann, K.A.; Science News, 145:148, 1994.
  • Anomalies and Curiosities of Medicine G.M. Gould and W.L. Pyle

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