London, July 6 (IANS): Mice that are exposed to the smell of cat urine early in life do not escape from cats later and become an easy prey, says a new study.

Researchers at Russia's A.N.Severtsov Institute of Ecology and Evolution have discovered that mice which smell cat urine early in life do not avoid the odour and, therefore, do not escape from their feline predators later in life.

"Because the young mice (less than 2-weeks-old) are being fed milk while being exposed to the odour, they experience positive reinforcement. So, they don't escape the cats when exposed to cat odour later on," said lead researcher Vera Voznesenskaya.

The researchers have identified the molecule in the urine responsible for these effects as L-Felinine.

"We already knew that odour affects reproduction in mice, in fact, this molecule (L-Felinine) is capable of blocking pregnancy in females and reducing the size of the litter," Voznesenskaya added.

Interestingly, while the mice don't escape from the odour later in life, they still experience hormonal changes throughout their life.

"Early exposure to cat odour changes behavioural reactions to, but not physiological (hormonal) responses in the mice, which remain elevated. In fact, mice that had experienced the odour showed stress response to cat odours in the same way as controls," the researcher said.