Overview
- Researchers identified a direct glutamatergic connection from galanin-expressing lumbar spinal neurons to bulbospongiosus motor neurons that produce the ejaculation burst pattern.
- These neurons responded to genital touch even when the brain was disconnected, demonstrating local spinal processing of sensory signals.
- Stimulating the circuit reliably triggered ejaculation in rats, whereas mice showed weakened bulbospongiosus responses upon repeated stimulation consistent with a refractory-like state.
- Targeted ablation of the galanin-positive neurons completely blocked ejaculation in rats, while mice exhibited delayed ejaculation and more failed mounts with only some males unable to ejaculate.
- The authors propose descending brainstem inhibition gates this spinal circuit until an ejaculatory threshold is reached, and they plan in vivo recordings during natural sex to test the model and map links to organs such as the prostate.