GISNe - Anatomia, Farmacologia e Medicina Legale

DIFFERENT INFLUENCES OF OVARIAN AND NON-GONADAL ESTROGEN
ON SPATIAL NAVIGATION
Leonida Fusani
Dipartimento di Fisiologia, Università di Siena
The decline of circulating estrogen after menopause has been put in relation with decreasing
performances in a number of cognitive functions including spatial navigation. However, several
peripheral tissues including the brain, and in particular the hippocampus, produce considerable
amounts of estrogen that is likely to act locally to regulate hormone-dependent functions. We
started investigating the different roles of ovarian and non-gonadal estrogen in modulating spatial
navigation in rats. Young and aged female rats were either ovariectomized, treated with an
aromatase inhibitor, or both, and were then tested with a Morris Water Maze protocol to study
the effects of the treatment on spatial reference memory. Our results show that both
ovariectomy and aromatase inhibition can affect retention of spatial information, however the
direction of the effects can be opposite depending on the age of the animals. These studies show
that the effects of ovariectomy go beyond the removal of circulating estrogen and caution should
be taken in making parallels between ovariectomy and menopause. In addition, non-gonadal
estrogen and probably neuroestrogen appear to play an important role in the regulation of
cognitive functions even in the presence of substantial amounts of ovarian estrogen.