O Visão Enfernal volta e a REvolta contra a Enfermagem como arte continua. A sua afirmação como ciência voltará a tomar lugar neste blogue, centrando a sua essência na divulgação da mais recente evidência científica.
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publicado por Visao ENFernal, em 02.01.09 às 12:13link do post | favorito

 

 

A subjectividade perante a dor é um facto mais que comprovado, contudo as diferenças sentidas atendendo ao género continuam uma incerteza. Há quem aponte que a dor sentida pelas mulheres é desvalorizada, enquanto outros defendem a maior capacidade no seu controlo por parte dos homens. Já um estudo realizado descreve mecanismos de analgesia fisiologicamente distintos entre ambos os sexos por alterações estruturais recentemente investigadas.

Utilizando como analgésico a morfina, obteve-se um resultado discrepante no alívio da dor entre os ratos machos e fémeas, uma vez que os machos apresentam maior sensibilidade à morfina por possuírem maior quantidade de receptores opióides no SNC. Neste sentido e segundo aponta o estudo, a morfina poderá provocar nas mulheres menor analgesia e maior quantidade de efeitos secundários, pelo que se existir alguma comparação possível entre os ratos e os humanos, será necessário repensar em novos mecanismos de analgesia para colmatar as necessidades das mulheres no controlo da dor.

 

In ScienceNOW Daily News 23 December 2008

 

«The new study used rats in part because they exhibit a clear sex difference in morphine sensitivity, explains lead researcher Anne Murphy, a neuroscientist at Georgia State University in Atlanta. In a standard lab test, for example, both male and female rats will withdraw a paw from a hot probe in 8 or 9 seconds. After a shot of morphine, the females might tolerate the probe for another second or two, but males let the paw linger up to 20 seconds, Murphy says.

 


 

In tomorrow's Journal of Neuroscience, Murphy and colleagues report that male rats have a higher density of μ-opioid receptors in a portion of the periaqueductal gray, a brain region implicated in previous experiments as a likely site of action for opioid drugs like morphine. Injecting morphine directly into this area had a powerful analgesic effect for male, but not female, rats. When the researchers killed neurons with μ-opioid receptors by injecting a toxin bound to a morphine lookalike compound, the drug lost its analgesic effect for males, but not females. Murphy says the findings, taken together, suggest that the difference in μ-opioid receptors in the periaqueductal gray explains the sex difference in morphine sensitivity in rats.

 

A better understanding of underlying neurobiology could one day lead to more effective pain drugs for women, Murphy says, adding that human studies have suggested that morphine produces less analgesia--and more side effects--in women.

 


 

"This is ... a breakthrough in finding a viable mechanism of action for sex differences in opiate analgesia in animals," says Richard Bodnar, a neuroscientist at City University of New York, Queens College. Other researchers have suggested that there may be sex differences in opioid receptor number or function in pain-related areas of the brain, but "this work is the first to definitively demonstrate such differences," says neuroscientist Rebecca Craft of Washington State University, Pullman.

Could it also explain differences in opioid sensitivity in people? "There are probably some parallels," says Craft, "but it's a bit early to tell how strong the relationship is between human and animal work in this area."»


http://www.jneurosci.org/cgi/content/abstract/28/52/14007

http://www.informationliberation.com/files/Morphine_sulfate2.jpg

http://sciencenow.sciencemag.org/cgi/content/full/2008/1223/2

http://meuslivros.weblog.com.pt/arquivo/pensar-12.jpg


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