I am curious to learn what are the neurological differences between those that have a high tolerance to pain than to those that do not. Specifically, by high tolerance to pain, I am referring to those people who can just 'work through' any moderate and even severe injury (e.g. a broken arm - as I have seen a couple of people do).
Much of the "higher order" sensation of pain is processed in the anterior cingulate cortex.
From Wikimedia Commons
There is a movement towards performing anterior cingulotomies in patients with intractable pain. These procedures are also used to help patients with severe depression or obsessive compulsive disorder, so we have some idea that this area of the brain is a point at which emotional salience is associated with our experience of the world around us. In the case of pain, post-surgical patients still experience all of the "lower level" symptoms (prostaglandin synthesis, etc.), but do not attach any meaning to them.
So, it is likely that individual differences in this anatomical region could partially account for those who can "work through" the pain versus those for whom it becomes overwhelming. It's certainly possible that those who can tolerate pain have a lower sensitivity to prostaglandins in their spinal circuitry, but I can't speak to whether that's a valid explanation.
Yen CP, Kuan CY, Sheehan J, Kung SS, Wang CC, Liu CK, Kwan AL (2009) Impact of bilateral anterior cingulotomy on neurocognitive function in patients with intractable pain. J Clin Neurosci., 16(2), 214-9.