Although it has been shown in vivo that glucocorticoids inhibit both spontaneous and GnRH-stimulated LH secretion, the opposite results were obtained in vitro. Glucocorticoids were also shown to inhibit GnRH-induced LHa and LHp mRNA transcription, but not that of FSHp. At the present stage, the effects of glucocorticoid on GTH synthesis and release in fish are poorly documented, although there is indication of lower GTH content under stressful conditions in salmonids. On the other hand, late in maturation, stress is also known to advance spawning in trout. It has been suggested that accelerated ovulation under stressful conditions late in maturation can occur as a switch in tactic for reproductive strategy when environmental conditions are unstable.
The distribution of the rtGR clearly overlaps that of the estrogen receptor in the brain and pituitary of the trout. This work also indirectly demonstrates that estrogen and GRs coexist in some hypothalamic cells, such as the TH neurons of the anterior preoptic region, and in the GTH-2 cells, indicating that potential interactions between these two receptors may occur in these cell populations.