Neurotransmitters: Replacement and Reuse in the Brain

[Mike Michaels]

OK I read that some neurotransmitters in the brain are replaced but others are reused.
Does that mean that some of them can't be replaced?

 

[Ryan_m_b]

Welcome to PF Mike. Short answer is no, all neurotransmitters can be synthesised but there are of course exceptions if the organism is unhealthy for whatever reason. Reuse is a good way of increasing neurotransmitter efficiency by not having to synthesise more all the time which would be nutrition and energy intensive.

 

[Mike Michaels]

I read that some neurotransmitters are "lost" during reusing process, where do the "lost" ones go?

 

[Ryan_m_b]

Do you have a specific reference? There are a lot of different neurotransmitter's along with their associated metabolic pathways! I don't know for sure (my neuroscience is a little rusty) but by "lost" it could be that they are not re-absorbed into the http://en.wikipedia.org/wiki/Axon_terminal" quick enough and so diffuse away, they are likely to be broken down quickly by relevant enzymes to prevent neural "short-circuits".

 

[Mike Michaels]

Once they're broken down where do they go?

 

[Ryan_m_b]

All over until eventually components are recycled or excreted as waste. Taking a neurotransmitter as an example this is an extremely simple map of dopamine degradation;

When chemicals are broken down the molecules produced, the by-products, catalysts and all other biomolecules used in the process get sucked into other chains of chemical reactions. We call these http://en.wikipedia.org/wiki/Metabolic_pathway" .

 

[Mike Michaels]

Do you think that some of the neurotransmitters, that I was born with, for example, are still present in the body as parts, or in some form?

 

[Ryan_m_b]

Do you think that some of the neurotransmitters, that I was born with, for example, are still present in the body as parts, or in some form?

I don't know, how old are you? If you were born recently it's highly likely

Seriously though it's not very likely. The majority of cells in your body are routinely broken down and replaced, even the cells that stay with you "for life" have all their sub-components broken down and replaced periodically, this is biology's take on the http://en.wikipedia.org/wiki/Ship_of_Theseus" . There's probably a half life for neurotransmitters that means even if they are recyclable the chances of them still being there after X units of time halves (I.e. neurotransmitter A has a 50% chance of still being in use in a month, 25% in two months, 12.5% in three months...0.02% in a year etc), this could obviously be different for different chemicals. I'm afraid I don't know about this for sure, I'm not even sure anyone does, but whilst I can't rule it out completely I would say it is extremely unlikely that there are any atoms within you that were there at your birth.

 

[Mike Michaels]

Well some of the neurons in your brain are never replaced (i read) even if they die.

 

[Evo]

Return of banned sockpuppet. Nice work though Ryan.