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ANSIEDAD / ESTRÉS

12 marzo, 2015

Fuente: Scientific American
Fecha: Marzo 2015

MADRID, 10 Mar. (EUROPA PRESS) –

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Investigadores estadounidenses han descubierto niveles más reducidos de la hormona del estrés en los descendientes de los supervivientes al Holocausto, una huella biológica de la experiencia traumática que sufrieron sus antepasados que podría predisponerles a un mayor riesgo de ansiedad.

El trabajo, cuyas conclusiones publica el portal ‘Scientific American’, ha sido llevado a cabo por un grupo de científicos del Icahn School of Medicine del Hospital Mount Sinai y el Veterans Affairs Medical Center en Nueva York (Estados Unidos), que en un trabajo previo habían determinado que los supervivientes a los campos de concentración nazis tenían alteradas estas hormonas, en comparación con otros judíos de su misma edad.

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En dicho estudio, vieron que los supervivientes tenían niveles más bajos de cortisol, una hormona que ayuda al cuerpo a recuperar la normalidad después de una situación traumática. Y en los que sufrieron el llamado trastorno de estrés postraumático (TEPT), los niveles eran aún más bajos.

Ahora, este nuevo estudio en descendientes de los supervivientes al Holocausto confirma esa menor presencia de esta hormona, lo que muestra como los efectos de ciertas experiencias traumáticas durante la infancia y la adolescencia puede perdurar en el tiempo e incluso transmitirse a las generaciones venideras.

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En concreto, vieron que, al igual que sus padres, muchos tienen niveles más bajos de cortisol, en especial cuando sus madres presentaban una experiencia de estrés postraumático.

Aunque la explicación de este déficit no está del todo claro, los autores lo atribuyen a la presencia de una enzima que podría descomponer el cortisol.

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Además, los autores creen que el efecto podría producirse durante su presencia en el útero materno, ya que dicha enzima se encuentra en niveles más elevados en la placenta para proteger al feto del cortisol circundante de la madre.

Los cambios epigenéticos sirven para preparar biológicamente a los descendientes a un entorno similar al de los padres, ha explicado Yehuda, que de hecho atribuye a esta huella biológica a un mayor riesgo de estrés y otros síndromes metabólicos como la obesidad, la hipertensión o la diabetes.

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Sin embargo, añade, todavía es demasiado pronto para saber con seguridad si estos cambios moleculares tienen repercusiones reales en la salud de estos descendientes. “Estamos justo al principio de poder entenderlo”, ha reconocido.

Acceso gratuito al texto completo.

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Descendants of Holocaust Survivors Have Altered Stress Hormones

Parents’ traumatic experience may hamper their offspring’s ability to bounce back from trauma

Credit: Wikimedia Commons
A person’s experience as a child or teenager can have a profound impact on their future children’s lives, new work is showing. Rachel Yehuda, a researcher in the growing field of epigenetics and the intergenerational effects of trauma, and her colleagues have long studied mass trauma survivors and their offspring. Their latest results reveal that descendants of people who survived the Holocaust have different stress hormone profiles than their peers, perhaps predisposing them to anxiety disorders.Yehuda’s team at the Icahn School of Medicine at Mount Sinai and the James J. Peters Veterans Affairs Medical Center in Bronx, N.Y., and others had previously established that survivors of the Holocaust have altered levels of circulating stress hormones compared with other Jewish adults of the same age. Survivors have lower levels of cortisol, a hormone that helps the body return to normal after trauma; those who suffered post-traumatic stress disorder (PTSD) have even lower levels.50295cca008b1e7f3725797b1d70992b 545f857c358b6551ca74c3c0aa15a68cIt is not completely clear why survivors produce less cortisol, but Yehuda’s team recently found that survivors also have low levels of an enzyme that breaks down cortisol. The adaptation makes sense: reducing enzyme activity keeps more free cortisol in the body, which allows the liver and kidneys to maximize stores of glucose and metabolic fuels—an optimal response to prolonged starvation and other threats. The younger the survivors were during World War II, the less of the enzyme they have as adults. This finding echoes the results of many other human epigenetic studies that show that the effects of certain experiences during childhood and adolescence are especially enduring in individuals and sometimes even across generations (right).Most recently, a new study looked at the descendants of the Holocaust survivors. Like their parents, many have low levels of cortisol, particularly if their mothers had PTSD. Yet unlike their parents, they have higher than normal levels of the cortisol-busting enzyme. Yehuda and her colleagues theorize that this adaptation happened in utero. The enzyme is usually present in high levels in the placenta to protect the fetus from the mother’s circulating cortisol. If pregnant survivors had low levels of the enzyme in the placenta, a greater amount of cortisol could make its way to the fetus, which would then develop high levels of the enzyme to protect itself.

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Epigenetic changes often serve to biologically prepare offspring for an environment similar to that of the parents, Yehuda explains. In this case, however, the needs of the fetus seem to have trumped that goal. With low levels of cortisol and high levels of the enzyme that breaks it down, many descendants of Holocaust survivors would be ill adapted to survive starvation themselves. In fact, that stress hormone profile might make them more susceptible to PTSD (below, yellow); previous studies have indeed suggested that the offspring of Holocaust survivors are more vulnerable to the effects of stress and are more likely to experience symptoms of PTSD. These descendants may also be at risk for age-related metabolic syndromes, including obesity, hypertension and insulin resistance, particularly in an environment of plenty.

Yet it is still too early in our investigation into the epigenetics of this complex stress-response system to know for sure whether these molecular changes indicate any real-world risks or benefits. “If you are looking for it all to be logical and fall into place perfectly, it isn’t going to yet,” Yehuda says. “We are just at the beginning of understanding this.”

Fuente:

http://www.scientificamerican.com

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