Androgens and indoleamines interact to control sexual dimorphisms in the rat spinal cord

Previous studies have shown that (i) androgen administration and (ii) depletion of serotonin can independently masculinise parts of the medial preoptic area and groups of motor neurons in the lumbosacral spinal cord when applied during the early postnatal period. We report here that these two control mechanisms interact in the neonatal female rat. Serotonin depletion by p-chlorophenyl alanine extends the 'critical period' during which androgens can act to stabilise neuron numbers within two sexually dimorphic motor neuron groups in segments L5-S1 (the spinal nucleus of bulbocavernosus and the dorsolateral nucleus), probably by slowing the rate of naturally occurring cell death. A non-dimorphic group of motor neurons (the ventromedial nucleus) was unaffected.