During prolonged starvation (>72 hours), the brain adapts to use ketone bodies. The transporter that allows acetoacetate and beta-hydroxybutyrate to enter brain cells is:
- A GLUT1 (glucose transporter 1)
- B FATP (fatty acid transport protein)
- C Monocarboxylate transporter (MCT) ✓
- D SLC16A family organic anion transporter
Correct answer: C. Monocarboxylate transporter (MCT)
Explanation
Ketone bodies (acetoacetate, beta-hydroxybutyrate) are monocarboxylate anions at physiological pH and cross the blood-brain barrier and enter neurons via monocarboxylate transporters (MCT1 and MCT2, encoded by SLC16A genes). GLUT1 transports glucose only. During prolonged starvation, up to 70% of the brain's energy can be derived from ketone bodies, sparing muscle protein from gluconeogenesis.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.