Glutamate-induced signal transduction pathways are crucial in the regulation of hippocampal plasticity. We have used the highly sensitive differential display method to investigate possible interaction of adrenal factors and glutaminergic transmission in hippocampal neurons in vivo. The analysis of 6000 hippocampal gene products derived from adrenalectomized and sham-operated rats, where both have received the glutamate analogue kainic acid (8 mg/kg body weight) led to the identification of 18 differentially expressed gene products which are subjected to transrepression by adrenal factors. In contrast, the analysis of 6000 hippocampal gene products of adrenalectomized rats with those of sham-operated rats resulted in the identification of two genes that are likely to be upregulated by adrenal factors.