Both classical and non-classical ERs participate in the neuroprotective actions of oestradiol. Thus, it has been shown that the neuroprotective actions of oestra¬diol in vivo and in vitro are imitated by selective agonists of ERα, ERβ, GPER and Gq-mER40–45 and are blocked by ER antagonists, ER silencing and ER knockdown45–47. It is unclear whether all the ERs participate in the protec¬tive actions of the molecule in all models of neuronal degeneration. Depending on the pathological model, some receptors seem to have more relevance than oth¬ers48. For example, ERα, but not ERβ, was shown to be involved in the neuroprotective action of oestradiol in a focal ischaemia model, after middle cerebral artery occlusion in mice49. However, both ERα and ERβ par¬ticipate in the induction of neurogenesis by oestra¬diol after focal ischaemia50 and in the neuroprotective action of the hormone after global cerebral ischaemia in rodents40,51. Also, different receptors seem to activate complementary and often redundant protective sig¬nalling pathways to produce the final neuroprotective effect (FIG. 3).