Well, I'm not an expert either. Just used to be interested on brain chemistry and related substances. So not worth much, but I'll give my thoughts and it's an interesting subject.
I don't know much about Tren, never used it and don't know anyone in preson that has. All I know is it has a strong recomping effect, raises prolactin and the risk for gyno, is generally harsh and seems to make people pissed off and horny, lol. But as with any drugs, the effects vary to some degree person to person, so if you say some people have the opposite effect on libido for example and on other effects, I'm not surprised and I believe you.
"Trens has effects on brain chemicals, mainly serotonin and dopamine but also on other neurotransmitters/chemicals ect. Most steroids give you a dopamine high, and so does tren but it can also do the opposite."
The Trens relation to dopamine is interesting, as prolactine and dopamine have a push-pull effect the way that when dopamine is up, prolactin is low and vice versa. Maybe the persons who don't have their prolactin highly raised on Tren experience the dopamine effect? Just random guessing.
"Dopamine is a reward system of sorts, a hit of dopamine makes you feel good"
Yes, and a big player in addictions and cravings. It also has motivational effect. You need dopamine to want to do and achieve things. So it's the motor and the goal, kind of. It's also needed as neural energy, but interestingly it's biggest effect on energy levels is how it 'buffers' noradrenaline. When you do any kind of an effort, noradrenaline is being released and too much of it and you just get exhausted. Dopamine 'pushes down' these noradrenaline levels.
"dopamine is also responsible for some roles in vasodilation"
I'm not familiar with dopamines effect on blood vessels. Stimulants that increase dopaminergic effects typically have a vasocontricting effect, but I don't know if dopamine has a role in the effect or not.
"Depending on the person tren can increase dopamine response or take it away."
That's interesting and would be interesting to learn the actual mechanism how it happens and why people have a different response.
"There's a difference tho between low dopamine and having low dopamine re-up take."
Maybe this was just a mispelling, but just in case, low reuptake will lead to higher effect of neurotransmitters, since it will stay present in the synapse for longer, when the reuptake of the neurostransmitter is inhibited. That's why SSRI's and MDMA is a dangerous coctail for example, cause' the Ex will increase serotonin release (along with other neurotransmitters like dopamine) and the SSRI will inhibit the reuptake of serotonin and you risk having a serotonin syndrome. -Drugs are bad, ummkhey-
"Same goes for dopamine (and the other brain chemicals) some ppl snort coke and can hump all night, others can't get a hard on. I think there's a strong connection there to dopamine response and blood flow. And same goes for tren, some ppl feel chemically castrated on tren, others turn into sexual deviants lol."
I would guess the effect of coce giving people difficulty getting a hard on to be more due to the vasocontrinction and not directly from dopamine. But like I said earlier I don't know what kind of role does dopamine play in the vasocontriction, if it does at all. You know the term "stim dick"? It can happen with pwo's that don't really have that big effect on dopamine, so I guess it could be more about adrenaline and noradrenaline, but that's just a guess. Sexual deviant on Tren? I know a guy. A British guy.
So yeah anyway a lot of noice with not much use this reply of mine ended up being
If interested, Andrew Hubermam has a lot of interesting YT vids about dopamine, neuroscience and things related. I think he has vids about testosterone and hormone related stuff too, but haven't watched them.