PMS can be a debilitating condition with symptoms such as anxiety, irritability, fatigue, sleep deprivation and increased sensitivity to pain. It appears to be triggered by the fall in the sex steroid hormone progesterone that occurs towards the end of the menstrual cycle and leads to a decline in its breakdown product allopregnanolone, which acts in the brain as a potent sedative and natural tranquilizer.
 

In other words, women with PMS are undergoing a type of drug withdrawal response from an in-built, tranquilizing steroid chemical in their brains.
 

The new research shows that antidepressants such as Prozac (fluoxetine) help maintain the chemical balance of this in-built tranquilizer.
 

Scientists from the University of Bristol and the University of Sao Paolo-Ribeirão Preto in Brazil have shown in rats that the anti-depressant alleviated symptoms of progesterone withdrawal such as PMS and possibly also postnatal depression.
 

Importantly, the researchers were able to demonstrate this effect on the same enzyme found in the human brain.
 

"The work is important because it introduces the possibility for targeted, intermittent therapy for PMS in women, with minimal side effects,” said Thelma Lovick, M.D., from the University of Bristol, who helped lead the research published in the journal European Neuropsychopharmacology.