Female rats that have ever given birth respond differently to cocaine than those who have never been mothers, as revealed by a group of researchers from the University of Michigan (USA) at the meeting of the Society for Neuroscience in New Orleans (USA).
The scientists used the microdialysis technique to measure the level of dopamine in an area of the brain callednucleus accumbens. Dopamine is a hormone related to pleasant sensations, and various scientific studies have shown thatcocaine increases its concentration in the brain. The results of the experiment revealed that, compared to virgin females, mother rats released less dopamine when consuming the drug.
In addition, a second experiment evaluated the effort that the females were willing to make to obtain cocaine. The system used gave access to it after pushing a door with the nose a certain number of times. The results indicate differences both as a function of maternity and the stress to which the rat had been subjected. As explained by EFE Verde,the stressed mother rats were unwilling to work for a dose of cocaine so hardlike rats that had never given birth or like mothers that had not been exposed to stress.
“Although we have not yet identified a mechanism that explains these differences, they suggest that maternal experience modifies the reward system and brain circuits affected by the drug,” said Jennifer Cummings, one of the authors. “The next step is to determine how factors such as hormonal changes during pregnancy and childbearing may contribute differently to this response.”
Although the findings cannot be directly extrapolated to humans, knowledge of brain chemistry and drug-related behavior in rats may provide clues for future more specific treatments. In new experiments, scientists will investigate the differences in response between mothers who have given birth but not raised their offspring and females who have not given birth but who have cared for the offspring of other rats.
