Emil Egecioglu, Luna Prieto-Garcia, Erik Studer, Lars Westberg and Elisabet Jerlhag*
Article first published online: 4 DEC 2014
- sexual behaviour
Ghrelin, a gut-brain signal, is well known to regulate energy homeostasis, food intake and appetite foremost via hypothalamic ghrelin receptors (GHS-R1A). In addition, ghrelin activates the reward systems in the brain, namely the mesolimbic dopamine system, and regulates thereby the rewarding properties of addictive drugs as well as of palatable foods. Given that the mesolimbic dopamine system mandates the reinforcing properties of addictive drugs and natural rewards, such as sexual behaviour, we hypothesize that ghrelin plays an important role for male sexual behaviour, a subject for the present studies. Herein we show that ghrelin treatment increases, whereas pharmacological suppression (using the GHSR-1A antagonist JMV2959) or genetic deletion of the GHS-R1A in male mice decreases the sexual motivation for as well as sexual behaviour with female mice in oestrus. Pre-treatment with L-dopa (a dopamine precursor) prior to treatment with JMV2959 significantly increased the preference for female mouse compared with vehicle treatment. On the contrary, treatment with 5-hydroxythyptohan (a precursor for serotonin) prior to treatment with JMV2959 decreased the sexual motivation compared to vehicle. In separate experiments, we show that ghrelin and GHS-R1A antagonism do not affect the time spent over female bedding as measured in the androgen-dependent bedding test. Collectively, these data show that the hunger hormone ghrelin and its receptor are required for normal sexual behaviour in male mice and that the effects of the ghrelin signalling system on sexual behaviour involve dopamine neurotransmission.
News: Jan 20, 2015
Swedish studies show that mice that receive a supplement of the “appetite hormone” ghrelin increase their sexual activity. Whether the hormone has the same impact on humans is unknown – but if it does, the researchers may have found the key to future treatments for sex abuse.
Ghrelin is a gastrointestinal hormone that is released from the stomach, and is involved in the stimulation of our appetite by activating the brain’s reward system.
Since the brain’s reward system also motivates us to seek a partner and to have sex, a group of researchers at the Sahlgrenska Academy decided to investigate whether ghrelin may also affect sexual behaviors.
The answer is: yes, at least in mice.
In the study, the researchers show that when mice receive a supplement of ghrelin, they increase their sexual activity and their efforts to find a partner. The effect is confirmed in a follow-up experiment, where mice that received a ghrelin inhibitor instead decreased 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,” says Elisabet Jerlhag, researcher at the Sahlgrenska Academy.
More research is needed
The studies show that the effects of the ghrelin are conveyed via dopamine, which is a known and important messenger in the brain’s reward system. The researchers’ conclusion is that both ghrelin and dopamine regulate normal sexual behavior in mice.
“However, this does not mean that ghrelin fills the same function in humans. Finding out requires significantly more research in the area. But ghrelin inhibitors may potentially be a key to future treatments for sex addiction and sex abuse,” says Elisabet Jerlhag:
“Addictive behaviours, including sex abuse, are one of our major social problems, and there is a great need for new treatment strategies. Hopefuly, our results can add another piece of the puzzle to this work,” says Elisbet Jerlhag.
The article The role of ghrelin signalling for sexual behaviour in male mice was published online in the journal Addiction Biology on December 4.