Global
ischemia during cardiac surgery, brain surgery and
stroke leads to lasting neuropsychological impairments. Previously we showed that low-dose
GYKI-52466 preconditioning protects against
kainic acid-induced
seizures and unilateral hypoxic-ischemic (HI) damage in rats. Here, we evaluated low-dose
GYKI-52466 on electrophysiological indices of hippocampal CA1 function after HI. Male Sprague-Dawley rats (26 days old) were administered saline or
GYKI-52466 (3mg/kg, s.c.) 90 min before left common carotid artery occlusion and allowed to recover 2h prior to placement in a
hypoxia chamber (1h; 8% O2/92% N2). On days 14 and 90 post-HI, contralateral and, where possible, ipsilateral hippocampal slices were prepared and population spikes and field excitatory postsynaptic potentials (EPSPs) recorded at 30-32 °C. Slices with population spikes ≥ 3 mV and/or field EPSPs ≥ 1 mV were accepted for long-term potentiation (LTP) and depression (LTD) studies.
GYKI-52466 preconditioning prevented the
stroke-induced suppression of population spikes and field EPSPs in both contralateral and ipsilateral hippocampi at 14 and 90 days. On days 14 and 90, both LTP and LTD were readily induced in both contralateral and ipsilateral hippocampi from
sham-operated controls. After
stroke, LTP was significantly impaired in contralateral and completely absent in ipsilateral hippocampi. In ischemic animals preconditioned with low-dose
GYKI-52466, LTP was readily induced on both sides. Hippocampal LTD was unaffected by either HI or GYKI preconditioning on both days 14 and 90. The present results indicate that prophylactic low-dose
GYKI-52466 preserves CA1 function and synaptic plasticity processes contralateral, and more importantly, ipsilateral to the site of damage.