Excitatory ncurotransmitter in brain is
**Core Concept**
The core concept being tested here is the identification of the primary excitatory neurotransmitter in the brain. This involves understanding the different types of neurotransmitters and their roles in synaptic transmission.
**Why the Correct Answer is Right**
Glu (Glutamate) is the primary excitatory neurotransmitter in the brain, responsible for excitatory synaptic transmission. It acts on several types of glutamate receptors, including AMPA (α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) and NMDA (N-methyl-D-aspartate) receptors. The activation of these receptors leads to an influx of calcium ions (Ca2+) into the postsynaptic neuron, which can trigger a series of downstream signaling events, including the release of other neurotransmitters and the generation of action potentials.
**Why Each Wrong Option is Incorrect**
* **Option A:** GABA (Gamma-Aminobutyric Acid) is the primary inhibitory neurotransmitter in the brain, acting on GABA receptors to reduce neuronal excitability.
* **Option B:** Acetylcholine is a neurotransmitter involved in various functions, including muscle contraction, heart rate regulation, and cognitive processes, but it is not the primary excitatory neurotransmitter in the brain.
* **Option C:** Dopamine is a neurotransmitter involved in reward processing, motor control, and other functions, but it is not primarily excitatory in the brain.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that excessive glutamate release and activation of glutamate receptors can lead to excitotoxicity, a process that contributes to neuronal damage and neurodegenerative diseases such as Alzheimer's and Parkinson's.
**Correct Answer: D. Glutamate**