Complex sentence: The ammonia produced in neurons is fixed into α-ketoglutarate by the glutamate-dehydrogenase reaction to form glutamate, then transaminated by alanine aminotransferase into lactate-derived pyruvate to form alanine, which is exported to astrocytes.
Split into simpler sentences: The ammonia produced in neurons is fixed into α-ketoglutarate by the glutamate dehydrogenase reaction to form glutamate. Then transaminated by alanine aminotransferase into lactate-derived pyruvate to form alanine which is exported to astrocytes.