London, Jan 28 (IANS): A stomach hormone involved in the stimulation of our appetite by activating the brain's reward system may also enhance sex drive, a first-of-its-kind study has documented.

Ghrelin is a gastro-intestinal hormone that is released from the stomach.

Since the brain's reward system also motivates us to seek a partner and to have sex, Swedish researchers found that mice that received a supplement of the "appetite hormone" increased their sexual activity.

It is already known that ghrelin affects the reward mechanisms that are triggered by food, alcohol and other addictive drugs.

"Our study now shows for the first time that ghrelin also plays a role in natural reward mechanisms like sex," said Elisabet Jerlhag from the Sahlgrenska Academy at University of Gothenburg.

In the lab, the researchers found that when mice receive a supplement of ghrelin, they increase their sexual activity and their efforts to find a partner.

The effect was confirmed in a follow-up experiment where mice that received a ghrelin inhibitor instead decreased their sexual activity.

The studies show that the effects of ghrelin are conveyed via dopamine which is a known and important messenger in the brain's reward system.

The researchers noted that both ghrelin and dopamine regulate normal sexual behaviour in mice.

"Addictive behaviours, including sex abuse, are one of our major social problems and there is a great need for new treatment strategies. Hopefully, our results can add another piece of the puzzle to this work," Jerlhag concluded.

The article was published online in the journal Addiction Biology.