A groundbreaking discovery by researchers from the University of Barcelona has identified the neuronal mechanisms that control pregnancy cravings.
Pregnancy cravings are common and are characterised by a sudden and uncontrollable urge to eat a certain food. However, pregnancy cravings can often be high-calorie foods, contributing to weight gain and obesity in pregnancy, which can have negative effects on the baby’s health.
“There are many myths and popular beliefs regarding these cravings, although the neuronal mechanisms that cause them are not widely known,” noted March Claret, lecturer at the Faculty of Medicine and Health Sciences at the University of Barcelona, and head of the IDIBAPS Neuronal Control of Metabolism Group. Claret leads, together with the researcher Roberta Haddad-Tóvolli, a study published in the journal Nature Metabolism, that provides novel evidence on the alterations of the neuronal activity that drive cravings in an animal model.
Pregnancy cravings and brain reward circuits
According to the research, during pregnancy, the brain of female mice alters the functional connections of the brain reward circuits, along with the taste and sensorimotor centres. Additionally, like the pregnancy cravings women experience, the female mice were more sensitive to sweet food, and they developed binge-eating behaviours toward high-calorie foods.
“The alteration of these structures made us explore the mesolimbic pathway, one of the signal transmission pathways of dopaminergic neurons. Dopamine is a key neurotransmitter in motivational behaviours,” noted Claret, member of the Department of Medicine of the UB and the Diabetes and Associated Metabolic Diseases Networking Biomedical Research Centre (CIBERDEM).
The team monitored the levels of dopamine and the activity of its receptor, D2R, to increase in the nucleus accumbens, which is a brain region involved in the reward circuit. “This finding suggests that the pregnancy induces a full reorganisation of the mesolimbic neural circuits through the D2R neurons,” noted Haddad-Tóvolli.
“These neuronal cells — and their alteration — would be responsible for the cravings, since food anxiety, typical during pregnancy, disappeared after blocking their activity.”
The consequences for the offspring
The team also discovered that persistent pregnancy cravings have consequences for the offspring. They affect the metabolism and development of neural circuits that regulate food intake, which can lead to weight gain, anxiety, and eating disorders.
“These results are shocking since many of the studies are focused on the analysis of how the mother’s permanent habits — such as obesity, malnutrition, or chronic stress — affect the health of the baby. However, this study indicates that short but recurrent behaviours, such as cravings, are enough to increase the psychological and metabolic vulnerability of the offspring,” concluded Claret.
The conclusions of the study could contribute to the improvement of nutritional guidelines for pregnant women, especially those experiencing pregnancy cravings, to ensure proper prenatal nutrition and prevent the development of diseases.