Quote:
Originally Posted by reverett123
Eventually one of those materials will run out and things will grind to a halt. The substance that runs out first and triggers the shutdown is called "the rate limiting factor."
And look at epinephrine (aka adrenaline). In a similar fashion, one of the things that epinephrine/adrenaline is made from is norepinephrine!
Now imagine this for a minute. You have just been informed by your sensory system that that guy on the bicycle is NOT going to stop. Other parts of your mind use that info and send word that you need some serious adrenaline and you need it now.
So you send the order to the adrenals and they start making adrenaline, a special hormone that is not stored but which is made fresh as needed. The raw material for that creation of adrenaline from starts pouring in to the adrenals and you note that it is mostly another hormone called "noradrenaline".
So you are mixing adrenaline as fast as you can but, then, the noradrenaline starts running low. Since you need more of that, a message goes out, "Cap'n, I don't think those entgines can handle Warp 7!" Just checking to see if everyone is still awake. 
But seriously, my point is that if we have a shortage of anything then we have to prioritize and determine who gets what. And your stash of dopamine sits at the end of a chain with adrenaline at the other end.
My head hurts. |
Rick,
This is really interesting; it reminds me of that paralysis issue we both know all too well. I have been to a few doctors and my neuro insists it is not PD. I have learned that essentially I am experiencing panic attacks and it all embodies what you are saying.
If we were to assign a medical name to the sudden, profound loss of muscle tone to my legs I would say it is most akin to cataplexy which is where an emotional event triggers sudden paralysis (mostly a symptoms of narcolepsy). In essence, it is the third "forgotten" response by the limbic system to fear. Everyone thinks flight or fight but freezing is a survival technique just as well. Weird thing is cataplexy is essentially sleep paralysis occurring at the worst possible times. What happens in the brain? It is a complete shut down of norepinephrine in the locus coeruleus.
Dopamine plays a big role because it reinforces the negative feedback loop, so while initially the freezing was response to a a very traumatic event in my former work place, it only now requires a public or social setting to trigger it. It responds to propanalol and an SSRI helps prevent them, but largely I can control it with my mind.
However, regardless what my doctor says, this is very much due to our fracked up catelochamine system: norepinephrine, epinephrine and dopamine. We would not have this happening if all was copacetic. Oddly, some how my limbic system is over responsive (too much peripheral dopa or flood of norepinephrine), so I go into panic attack by just thinking of it, but then end up in a cataplexic state. I am guessing my amygdala is overly sensitive. What I don't get is why I get a flood of adrenaline to fuel the panic attack, but at same time I do not have enough to avoid the freezing. This is why the noodle legs are not immediately responsive to levodopa. Serotonin and levodopa can both produce dopamine, but norepinephrine is formed only after dopamine. I am thinking this is why it takes me 3 doses to walk again.
Makes me think that amino acid precursors are really important for some of us. I know l-tyrosine's role, but I just read that phenylalaline might be beneficial too.
Catecholamine Metabolism: A Contemporary View with Implications for Physiology and Medicine (The good stuff begins on page 337.)