The study uses Pet-1 mutant mice, genetically altered mice carrying a mutation in a gene that directs the development of the brain serotonin neurotransmitter system, to investigate the system’s role in maternal behaviour and its impact on offspring survival.
“Alterations in brain serotonin levels have been linked to several mental health disorders such as depression and anxiety,” said lead researcher Evan Deneris. “However, despite the prevalence of postpartum depression and the frequent use of serotonergic drugs to treat this disorder, a requirement for maternal serotonin function in the mother’s behaviour toward her offspring had not been convincingly demonstrated, until now.”
Although Pet-1 deficient mice mothers showed normal rates of pregnancy and gave birth to normal numbers of offspring, none of their offspring survived to five days of age, therefore directly demonstrating a critical role for the brain serotonin neurotransmitter system in reproductive success of mice.
Further studies indicated that a specific deficiency of maternal care was the cause of pup mortality. Rodent neonates are not able to maintain proper body temperature on their own; essential maternal care includes construction of proper nests and huddling of offspring in the nests for warmth. Although Pet-1 deficient mothers nursed their offspring they often failed to build suitable nests and never organised offspring in a huddle. Thus, offspring neglect led to death from cold exposure.
The study also showed that a partial restoration of Pet-1 function in the developing brain of females partially restored their serotonin levels and maternal behaviour in adulthood. This finding indicated that subtle changes in the embryonic formation of the brain serotonin system in females can impact the quality of the maternal care they later provide for their offspring. Future studies with Pet-1 deficient mothers may help to further elucidate the link between serotonin and maternal behaviour and lead to new therapeutic approaches.
MEDICA.de; Source: Case Western Reserve University