Synaptic adaptation to repeated hypoglycemia depends on the utilization of monocarboxylates in uinea pig hippocampal slices. Diabetes

This report provides in vitro evidence that synaptic activity becomes resistant to repeated hypoglycemia, i.e., hypoglycemic synaptic adaptation occurs. Synaptic function was estimated by the amplitude of the postsyn-aptic population spike (PS) recorded in the granule cell layer of guinea pig hippocampal slices. ATP, phospho-creatine (PCr), glycogen, and glucose concentrations were measured to investigate energy metabolism ho-meostasis. Glucose deprivation produced a complete elimination of the PS amplitude, with a 50 % inhibition by 10.6 min, and a 15 % reduction in ATP and PCr concentrations. Low-glucose (0.5–1 mmol/l) medium gradually depressed the PS. After recovery from glucose depletion, repeated glucose deprivation produced a slowly developing depression of PS, with a 50 % inhibi