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Abstract

In Japanese quail, the presence of aromatase (oestrogen synthase) in the dorsal horn of the spinal cord suggests that spinal sensory processes might be controlled by local actions of oestrogens. This is supported by the presence of oestrogen receptors and aromatase in the dorsal horn of the spinal cord in rats, and by the alteration of sensitivity by oestrogens in various mammalian species and also in canaries. We investigated whether oestrogens that are locally produced in the quail spinal cord can bind to specific receptors in the vicinity of their site of synthesis. We demonstrate the presence of numerous oestrogen receptor α-immunoreactive (ERα-ir) cell nuclei, predominantly in laminae II and, to a lesser extent, I and III of the dorsal horn of the spinal cord (i.e. in the area where aromatase was previously identified). ERα-ir cells were also seen in various parts of the intermediate zone (laminae V–VII). This presence of ERα-ir cells in the dorsal horn and intermediate zone fits in well with the distribution of ERα-ir cells in homologous areas in mammals, including rats. Only a few labelled cells were found in the ventral horn in the cervical, brachial, thoracic and first lumbar segments, but a conspicuous dense group of large ERα-ir cells was identified in lamina IX of the ventral horn in synsacral segments 8–10, which contain the motoneurones innervating the muscles of the cloacal gland. The presence of ERα-ir cells in lamina IX of these synsacral segments in quail contrasts with the finding that motoneurones innervating penile muscles in rats contain androgen, but not oestrogen receptors, and are influenced by androgens rather than by oestrogens. Together, these data suggest that spinal actions of oestrogens may modulate the sensory and motor systems that participate in reproduction, as well as other nonreproductive functions in quail.