Secretory phospholipase A Type II (sPLA₂) may modulate neuronal function, under both physiological and pathological conditions. This 14 kDa enzyme, present in synaptic vesicles, is released by depolarization or neurotransmitter stimulation. Moreover, ischemia induces sPLA₂ gene expression in rat brain. We evaluated the effect of sPLA₂ from bee venom (BV) alone and with glutamate (GLU) on neurotoxicity through lactate dehydrogenase (LDH) release, intracellular free calcium concentration ([Co²⁺]_i), and [³H] arachidonic acid (AA) release on primary cultures of cortical neurons. At 0.01 μml, BV was not toxic, did not affect basal oscillations in ([Co²⁺]_i), but did induce [³H]AA release from phospholipids (PL). BV dose dependently (0.025-10 7mu;g/ml) caused neurotoxicity, altered [Ca²⁺]; dynamics, and stimulated [³H]AA release. GLU (80 μM) toxicity was similar to 0.5 μ g/ml BV (100% above control). Concentrations of BV (0.01 to 0.05 μ g/ml), which resulted in a 40-80% increase in LDH release when combined with GLU (80 μ M), elicited synergy in neurotoxocity (2.5-fold higher LDH release than their individual LDH values) and [3H]AA (1.5-fold). MK-801 blocked the synergy but not the BV effects. In contrast to the sustained [Co²⁺], response induced by GLU, BV dose-dependently (0.5-10 μ g/mL) induced a trancient increase in [Ca²⁺]_i followed by decreased basal oscillations and a significant fall in [Ca²⁺]_i. These results indicate that calcium-independent toxicity may occur at low sPtA₂ concentrations and provide evidence for modulatory roles of sPLA₂s in neuronal signal transduction.