The concentration of the hormone prolactin in the blood is controlled by dopamine. However, the system can be thrown off balance by certain drugs, especially antipsychotics, which can result in sexual side effects. A new study from Karolinska Institutet in rats, published in the journal Cell Reports, shows how dopamine can regulate itself and provides new knowledge about how the side effects arise.

The researchers behind the study examined a group of dopamine producing neurons that control the secretion of prolactin, a hormone that leads to the production of breast milk, suppresses fertility and stimulates appetite in new mothers. Under most circumstances beyond pregnancy, blood levels of prolactin are usually suppressed by the neurotransmitter dopamine, which serves to inhibit the prolactin cells.

Antipsychotics

But the inhibitory mechanism can be lost, as is commonly seen in patients on antipsychotics that block dopamine receptors, resulting in sexual and reproductive problems such…