Effects of deprivation of oxygen and glucose on the neural activity and the level of high energy phosphates in the hippocampal slices of immature and adult rat

Abstract

To investigate neural activity and cerebral energy metabolism during anoxia in neural tissue of different ages, hippocampal slices were prepared from 4-, 7- and 10-day-old, and adult rats. Using these slices, the postsynaptic potential (psp) was recorded in the pyramidal cell layer of the CA1 area. Adenosine triphosphate (ATP), phosphocreatine (PCr) and lactate levels in the slices were measured during oxygen and glucose deprivation. The level of oxygen consumption was also measured for each slice in its resting state. After the onset of oxygen and glucose deprivation, the psp of slices from 4-, 7- and 10-day-old, and adult rats ceased completely in 22, 9, 5.6 and 4.6 min, respectively. Using initial changes in the levels of ATP, PCr and lactate during deprivation, the energy use rates of respective slices were calculated to be 1.09 approximately P mmol/g DNA/min in 4-day-old, 2.93 in 7-day-old, 3.42 in 10-day-old and 4.75 in adult rats. The oxygen consumption rates at rest for slices taken from 4-, 7- and 10-day-old, and adult rats were 0.13, 0.24, 0.47 and 0.80 approximately O2 mmol/g DNA/min, respectively. Thus, differences in rates of energy use and oxygen consumption between immature and adult brain tissues correlated well with those of psp decay time during oxygen and glucose deprivation. The levels of ATP at the time of psp cessation in 4-, 7- and 10-day-old and adult brain slices were less than 23, 39, 51 and 61% of the initial value, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)