Neurotransmitters and the control of hypophyseal gonadal functions: possible implications of endocrine disrupters

The reports published so far may suggest that chemicals of plant origin or obtained by synthesis may influence the central mechanisms controlling gonadotrophin secretion through a variety of different mechanisms. Some compounds of herbal origin seem to affect the neuroendocrine system acting as oestrogens (zearalenone and genistein). Also some synthetic chemicals seem to display an oestrogenic influence on the neuroendocrine system (the pesticide chlordecone, some of the polychlorinated biphenyls and of the alkylphenol ethoxylates). However, other synthetic molecules may affect the central control of gonadotrophin secretion acting like anti-androgens (pesticides like DDT, dioxin and vinclozolin) or by disrupting the adrenergic regulation of the hypothalamo-pituitary-gonadal axis (the pesticides chlordimeform and thiram). These conclusions refer only to a few compounds and are largely based on indirect evidence; in many cases specific experiments are still to be performed. For many other chemicals the possible mechanism of action on the neuroendocrine system is still to be elucidated. However, the information collected so far seems to suggest that the influence exerted by environmental endocrine disrupters on the neuroendocrine system is more complex than previously anticipated.