Overview

• Researchers identified galanin-expressing spinal neurons that form direct, glutamatergic excitatory connections onto bulbospongiosus motor neurons responsible for the ejaculation burst pattern.
• Optogenetic activation of these neurons reliably produced ejaculation in rats, whereas in mice the same stimulation drove bulbospongiosus firing without a complete ejaculation.
• In mice, repeated stimulation weakened motor output consistent with a refractory state, supporting a proposed descending brainstem inhibition that gates spinal activity.
• Targeted ablation of the galanin-positive neurons blocked ejaculation in rats but in mice primarily disrupted mating sequences and only partly reduced ejaculation success.
• The authors suggest rats may better model reflexive ejaculation while mice may capture integrated regulation more relevant to humans, and they plan in vivo recordings during sexual behaviour to test circuit interactions with brain and peripheral organs.