Thursday, 18 August 2011

Rats attracted to cats?

I'm not really obsessed with Toxoplasma gondii but you have to admire this organism. Read on to see why.

I discussed T.gondii in a previous post on schizophrenia in light of work like this one from Faith Dickerson and colleagues. Now a new study has come to quite a startling conclusion: T.gondii might make rats sexually attracted to cats (or at least cat urine).

The study in question is this one* from Patrick House and colleagues from Stanford University. They looked at what happens to certain parts of the brain of infected rats and found increased activity in parts of the limbic system. The limbic system is also known as the paleomammalian brain by people like Paul D. MacLean (the father of Evolutionary Psychiatry) and includes quite a few structures known to be involved in emotions and hormone regulation.

In the current study, various alterations of limbic response were noted in infected rats in response to cat urine. The authors suggest that T.gondii may modulate behaviour by shifting the 'defensive' neural pathway of infected rats to the 'reproductive' pathway; in effect rather than running away, the rats are sexually attracted to cat urine.

Conditions like schizophrenia and obsessive-compulsive disorder (OCD) indicate perhaps more than a passing association with exposure to T.gondii as represented by elevated antibodies to the organism. Indeed even some cases of suicide might also be linked to T.gondii. What studies like the one from House et al suggest is that neural targets, areas of the brain, likely to be affected by infection should be the subject of much more investigation. Once again environment shows its hand.

* House PK. et al. Predator cat odors activate sexual arousal pathways in brains of Toxoplasma gondii infected rats. PLoS ONE. August 2011.