Neurotransmitter Associated Diseases and Disorders
Summary of the main physiological functions of key neurotransmitters:
🔹 Neurotransmitters: General role
Neurotransmitters are chemical messengers that:
- Transmit signals across synapses
- Modulate neuronal circuits in the brain, spinal cord, autonomic nervous system, and peripheral nervous system
- Regulate cognition, mood, motor control, autonomic function, and behavior
🔹 Key neurotransmitters and their physiological functions
| Neurotransmitter | Primary functions | Physiological roles |
| 🧠 Acetylcholine (ACh) | Excitatory in CNS & PNS | – Cognitive function (learning, memory) – Neuromuscular junction: triggers muscle contraction – Parasympathetic nervous system: slows heart rate, stimulates digestion |
| 🌊 Glutamate | Major excitatory CNS neurotransmitter | – Synaptic plasticity, learning, memory (long-term potentiation) – General excitatory tone in CNS |
| 🛑 GABA (gamma-aminobutyric acid) | Major inhibitory CNS neurotransmitter | – Reduces neuronal excitability – Maintains balance to prevent overexcitation (e.g., seizures) – Promotes relaxation, sleep |
| 🌟 Dopamine | Modulatory (mainly excitatory) | – Motor control (nigrostriatal pathway) – Reward, motivation (mesolimbic/mesocortical pathways) – Endocrine control (prolactin inhibition) |
| 😌 Serotonin (5-HT) | Modulatory | – Mood regulation, well-being – Appetite, satiety – Sleep-wake cycle – GI motility (majority of 5-HT in gut) |
| ⚡ Norepinephrine (NE) | Excitatory | – Sympathetic nervous system: “fight or flight” responses (↑ HR, ↑ BP) – Attention, alertness, arousal |
| 😡 Epinephrine (Adrenaline) | Hormone + neurotransmitter | – Acute stress response – Augments NE effects (↑ cardiac output, bronchodilation) |
| 😊 Histamine | Excitatory/modulatory | – Wakefulness/arousal – Appetite suppression – Regulation of inflammatory responses (also a peripheral immune mediator) |
| 🔥 Glycine | Major inhibitory neurotransmitter in spinal cord | – Inhibits motor neurons (spinal cord reflex control) – Important for coordinated movement |
| 🧡 Endorphins / enkephalins | Neuropeptides | – Natural analgesia (pain suppression) – Modulation of mood, reward, stress |
| 🔗 Substance P | Neuropeptide | – Transmission of pain signals (nociception) – Involved in inflammatory processes |
🔹 Organized by physiological domains:
✅ Central nervous system (CNS)
- Excitation: Glutamate
- Inhibition: GABA, glycine (spinal cord)
- Modulation: Dopamine, serotonin, norepinephrine, histamine, neuropeptides (endorphins, substance P)
✅ Peripheral nervous system
- Autonomic nervous system control: Acetylcholine (parasympathetic, sympathetic ganglia), norepinephrine (sympathetic postganglionic)
- Neuromuscular transmission: Acetylcholine at neuromuscular junction
✅ Behavioral / mood regulation
- Reward and motivation: Dopamine
- Stress response: Norepinephrine, epinephrine
- Pain modulation: Endorphins, substance P
✅ Sleep-wake cycles
- Arousal: Histamine, norepinephrine, serotonin
- Sleep induction: GABA
🔹 Summary in one sentence:
Neurotransmitters coordinate brain and body function by regulating excitatory, inhibitory, and modulatory signaling — essential for movement, mood, cognition, autonomic control, sensory processing, and homeostasis.