Expression of mRNA and proteins for testicular steroidogenic enzymes and brain and pituitary mRNA for glutamate receptors in rats exposed to immobilization stress

The objectives of this study were to determine whether stress attenuates the pituitary LH response to excitatory amino acids by altering expression of glutamate receptor 1 (GluR1) and N-methyl- d-aspartic acid (NMDA) receptor mRNA levels in the hypothalamus or pituitary, and assess whether stress influences testicular levels of mRNA or protein for steroidogenic enzymes. Three hours (h) of immobilization stress was associated with a greater than 7-fold increase in serum corticosterone, and a marked reduction in serum testosterone (T) concentrations. Stress did not significantly alter hypothalamic or pituitary GluR1 and NMDA receptor mRNA levels. Although transcript levels for P450 SCC and P450 17α mRNA in the testis were unchanged in stressed rats, western blotting of testicular fractions revealed reduced amounts of P450 SCC and 3β-HSD, but not P450 17α. The data suggest that immobilization stress reduces T production by suppressing the translation of transcripts for P450 SCC and 3β-HSD, but the attenuated LH response of stressed animals to NMDA is not mediated by altered hypothalamic or pituitary expression of GluR1 and NMDA receptor levels.