Pregnant mice block out unwelcome admirers

July 21st, 2008 - 2:08 pm ICT by IANS  

Washington, July 21 (IANS) Pregnant mice protect their unborn by keeping males at bay with the help of a remarkable mechanism. Such mice block the smell of their urine that can cause miscarriage, besides reactivating the ovulatory cycle.

The scent affects pregnancy by inhibiting the release of the pregnancy hormone prolactin. This phenomenon is often called the Bruce effect and creates a mating opportunity for the alien male.

A surge of the chemical signal dopamine in the olfactory bulb creates a barrier for male odours, according to researchers of European Molecular Biology Laboratory (EMBL) in Monterotondo, Italy.

The dopamine flood is triggered by physical stimulation during mating and progressively impairs the perception and discrimination of social odours contained in male urine.

Treating pregnant mice with chemicals that block the dopamine receptor D2 abolished the barrier effect, restored odour sensing and favoured pregnancy disruption.

Liliana Minichiello and her team at the EMBL Mouse Biology Unit discovered how molecular mechanism underpins this change in sensitivity to male odours.

The findings unexpectedly reveal the main olfactory bulb as a key control centre of social and reproductive behaviour.

These findings have been reported in the current issue of Nature Neuroscience.

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