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🔹 Important Receptors
🧠 A. Ligand-Gated Ion Channel Receptors (FAST transmission)
Receptor | Neurotransmitter | Ion | Key Drugs | Classic Exam Point |
GABAᴬ | GABA | Cl⁻ | Benzodiazepines, Barbiturates | Inhibitory |
NMDA | Glutamate | Ca²⁺ | Ketamine, Memantine | Excitotoxicity |
Nicotinic (N) | Acetylcholine | Na⁺ | Nicotine | Ganglia, NMJ |
5-HT₃ | Serotonin | Na⁺/Ca²⁺ | Ondansetron | Vomiting |
📌 Rule:
Ion channel receptors = fastest neurotransmission
🧠 B. G-Protein–Coupled Receptors (SLOW, modulatory)
🔸 Gi (↓ cAMP)
Receptor | Neurotransmitter | Key Drugs | Exam Pearl |
D₂ | Dopamine | Antipsychotics | EPS, prolactin |
5-HT₁ | Serotonin | Buspirone, Triptans | Anxiolysis |
α₂ | Noradrenaline | Clonidine | ↓ NE release |
μ-opioid | Endorphins | Morphine | Analgesia |
🔸 Gs (↑ cAMP)
Receptor | Neurotransmitter | Key Drugs | Exam Pearl |
β₁ | Noradrenaline | Dobutamine | Heart rate ↑ |
β₂ | Noradrenaline | Salbutamol | Bronchodilation |
D₁ | Dopamine | Fenoldopam | Renal vasodilation |
5-HT₄ | Serotonin | Cisapride | GI motility ↑ |
🔸 Gq (↑ IP₃/DAG)
Receptor | Neurotransmitter | Key Drugs | Exam Pearl |
α₁ | Noradrenaline | Phenylephrine | Vasoconstriction |
M₁ / M₃ | Acetylcholine | Bethanechol | Secretions ↑ |
H₁ | Histamine | Antihistamines | Allergy |
🧠 C. Enzyme-Linked / Tyrosine Kinase Receptors
Receptor | Hormone | Example | Exam Pearl |
Insulin receptor | Insulin | — | Tyrosine kinase |
Growth factor receptors | EGF, PDGF | — | Cell growth |
🧠 D. Intracellular (Nuclear) Receptors
Receptor | Ligand | Exam Line |
Steroid receptors | Estrogen, Cortisol | Act at gene level |
Thyroid hormone receptor | T₃/T₄ | Nuclear binding |
Vitamin D receptor | Vitamin D | Ca²⁺ regulation |
placental transfer of drugs
