Posted on 09/25/2009 12:15:45 PM PDT by ConservativeMind
Scientists at Georgia State University have uncovered the mechanisms of how pain in infancy alters how the brain processes pain in adulthood.
Research is now indicating that infants who spent time in the neonatal intensive care unit (NICU) show altered pain sensitivity in adolescence. These results have profound implications and highlight the need for pre-emptive and post-operative pain medicine for newborn infants.
The study, published online in the journal Frontiers in Behavioral Neuroscience, sheds light on how the mechanisms of pain are altered after infant injury in a region of the brain called the periaqueductal gray, which is involved in the perception of pain.
Using Sprague-Dawley rats, Jamie LaPrairie, a graduate student in associate professor Anne Murphy's laboratory, examined why the brief experience of pain at the time of birth permanently decreased pain sensitivity in adulthood.
Endogenous opioid peptides, such as beta-endorphin and enkephalin, function to inhibit pain. They're also the 'feel good' substances that are released following high levels of exercise or love. Since these peptides are released following injury and act like morphine to dampen the experience of pain, LaPrairie and Murphy tested to see if the rats, who were injured at birth, had unusually high levels of endogenous opioids in adulthood.
To test this hypothesis, LaPrairie and Murphy gave adult animals that were injured at the time of birth a drug called naloxone. This drug blocks the actions of endogenous opioids. After animals received an injection of naloxone, they behaved just like an uninjured animal.
The scientists then focused on the periaqueductal gray region to see if inflammation at birth altered the natural opioid protein expression in this brain region. Using a variety of anatomical techniques, the investigators showed that animals that were injured at birth had endogenous opioid levels that were two times higher than normal.
While it's beneficial to decrease pain sensitivity in some cases, it's not good to be completely resilient to pain.
"Pain is a warning sign that something is wrong," Murphy explained. "For example, if your hand is in water that's too hot, pain warns you to remove it before tissue damage occurs."
Interestingly, while there is an increase in endorphin and enkephalin proteins in adults, there is also a big decrease in the availability of mu and delta opioid receptors. These receptors are necessary in order for pain medications, such as morphine, to work. This means that it takes more pain-relieving medications in order to provide relief as there are fewer available receptors in the brain. Studies in humans are reporting the same phenomenon.
The number of invasive procedures an infant experienced in the NICU is negatively correlated with how responsive the child is to morphine later in life; the more painful procedures an infant experienced, the less effective morphine is in alleviating pain.
The study by LaPrairie and Murphy has major implications for the treatment of infants in neonatal intensive care. On average, a prematurely born infant in a neonatal intensive care unit will experience 14 to 21 invasive procedures a day, including heel lance, insertion of intravenous lines, and intubation. All of these procedures are quite painful and are routinely conducted without prior analgesics or anesthetics.
"It's imperative that pain be treated," Murphy said. "We once assumed that a newborn infant is insensitive to pain, and this is clearly not the case. Even at that period of time, the central nervous system is able to respond to pain, and our studies show that the experience of pain completely changes the wiring of the brain in adulthood."
The next steps in Murphy's research include the study of how neonatal injury at birth alters stress responses, as well as the affects of infant injury on long-term learning and memory.
More information: The article, titled "Neonatal injury alters adult pain sensitivity by increasing opioid tone in the periaqueductal gray," appears in the September 2009 edition of journal Frontiers in Behavioral Neuroscience, Vol. 3, p. 1-11.
...and the S&M community in SF too!!! :-O
Ruh Roh - you did it now, with the circumcision comment. The “intactivists” will soon be here.
Well, I was circumsized (without my permission) and could not walk for almost a year.
Well, I was circumsized (without my permission) and could not walk for almost a year.
Interesting story.
“We once assumed that a newborn infant is insensitive to pain, and this is clearly not the case.”
Having some current (and very acute) knowledge on this subject - pain, and pain remedies - I cannot imagine why they ever thought that way.
How did they miss the medical knowledge that the basis of “pain” (what human tissue identifies as “bad”) originates in the more “primitive” area of nerve development known as the sympathetic nervous system (part of the autonomic nervous system), which operates at a lower order of intercourse with the human brain, with some of its transmissions going no higher than the brain stem.
A worm has the sympathetic nervous system - knows hot from cold and touch - but has NO brain. And many humans who, through some tragic event, seem to loose most all recognizable brain function, continue to make physical responses to touch, heat and cold.
An newborn (or pre-born) infant’s cognitive brain function may not have developed to bring forth cognitive responses to pain, but that does not mean that its body does not yet know and “feel” pain.
Infants had open heart surgery without anesthesia in the fifities.
“Infants had open heart surgery without anesthesia in the fifities.”
That may be true, but I believe they (the medical community) already had knowledge then about the nervous system, that told the fully informed that sensory registration (neuro-transmission) of pain signals, in the broader sense, is present and working in the body at infancy. Their infantile brain and infantile cognitive functions just haven’t formed, or “learned” a cognitive response - move a muscle, moan and groan - to it yet.
But they have increased blood pressures, increased heart rates, and facial grimaces.
“But they have increased blood pressures, increased heart rates, and facial grimaces.”
The human body will have increased blood flow and heart rates, as a pain response, in infancy, even before “facial grimaces”, as the majority of pain receptors are from the same part of the nervous system that helps control heart rate and the blood flow system - the sympathetic nervous system, and they are working as soon as is the heart.
The “pain” response is there, with or without our awareness of it. It is derived from the basic life, flight-or-fight response, basic to the working of the sympathetic nervous system and even the body of worm, with no brain (no more than a primitive “ganglia” [junction box] of very basic nerve cells), responds to all the touch and temperature cues we know as pain.
Good one!
What!!!???
I dont know, the babies I watched being circumcised as a student certainly looked uncomfortable
I take care of them; believe me, they cry from pain; you can’t hear them when they’re intubated; but you can see their little faces scrunched up.
You probably couldn’t even put together full sentences for years after your circumcision as well.
Check this out: http://www.circumstitions.com/
At 9 years old, I received 3 deep fillings without any Novocaine since the Novocaine had a profound effect on local motor functions (uncontrolled drooling and a sensation that my face was swollen like a basketball). During the procedures, I had to find my happy place to endure the high pitched whistle of the pneumatic drill boring deeper and deeper into the dentine of 3 molars. But, at that time in my life, it was preferable to the x-cain.
Many years later, I'm still trying to unwind neurological issues likely caused by blunt force trauma inflicted by my "dad" as a young child. I wounder how how much of my gray matter was scattered and paths were tattered...
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