Most likely dopamine depletion is a consequence of dopaminergic cell death and not the other way around. Reasons 1) Giving more dopamine does not really save the dopaminergic neurons in humans and animals. 2) Dopaminergic cell death is most likely due to over activation by something else, that is still unknown because hyperpolarization by activation of GABA receptors which is inhibitory seems to help 3) The  dopaminergic cell can be killed by something like pesticides or MPTP which is well known.

Hope this helps

In my opinion, both are consequences of a common cause : progressive degeneration of dopamine-secreting cells, leading to a decrease of secretion and finally to cell death.

True.

Well, I am kind of on the hypothesis that the GABA system should be the main target for treating neurodegeneration. We just submitted a review on this, hope to get published soon. In my opinion, the over excitation of the neurons is THE reason for neuronal death. So the treatment would be to make them "calm down" by hyperpolarization. In fact a lot of drugs based on the GABA system or even sleeping pills such as benzodiazipines are in clinical trial for treating Alzheimer's.

Hi Bernard and Nurul

Thanks for responding. Do you refer vesicular dopamine as a source of secretion? Well I'm working with oxidative stress hypothesis and I believe that DA oxidation in cytoplasm leads to decrease in DA, reduction in densities of DAT, VMAT2 and TH (axonal markers). Chronic treatment also leads to glutamatergic activation that produces nitric oxide which is again a key player in apoptosis further. Apart from that mitochondria is also involved in apoptosis. But the things that are confusing me here are: Does this axonal terminal degradation occurs first or as a simultaneous event with other apoptosis factors such as mitochondria and nitric oxide? So is that a functional loss of DA neurons first that leads to loss of DA and then to cell death or is that a functional loss that leads to cell death and then DA loss??

1.Dopaminergic cell death results in dopamine depletion.

2.Dopamine depletion, as far as i know, is not demonstrated to result in dopaminergic cell death.