Which protein is a well-known survival factor for immature neurons and is also an important neurotransmitter used by nociceptors in the pain pathway that induces plasticity in second order neurons

The correct answer is: Brain-derived Neurotrophic factor.

Explanation:

The brain-derived neurotrophic factor (commonly abbreviated to BDNF) is a protein from a family related to the growth of nerves that also works as a neurotransmitter.

In the brain, the BDNF is active in areas like the basal forebrain, the cortex, and the hippocampus, where learning, memory, and higher thinking take place.

BDNF plays a key role in the survival of neurons and the process of synaptogenesis, which is why the decrease of this protein is linked to several neuropsychiatric conditions like depression and schizophrenia.