A study in Nature Metabolism indicates that pregnancy affects the connectivity of the brain, in particular the components of the dopaminergic circuit
Although the general belief is that cravings serve to support embryonic growth, its origin is in the brain, where the neural circuits related to motivation and desire that drive eat sweet and caloric productsaccording to a study with mice.
The research published by Nature Metabolism and signed by Spanish researchers indicates that pregnancy affects brain connectivityparticularly those components of the dopaminergic circuitwhich intervenes in the perception of rewarding stimuli and drives episodes of anxiety about food.
Cravings can not only influence weight gain or obesity, but have Long-lasting metabolic consequences in offspringas the first signatory of the study, Roberta Haddad-Tóvolli, from the August Pi i Sunyer Biomedical Research Institute, explains to Efe.
Sugary drinks and tasty foods
Although the intake of highly appetizing foods is a common feature in pregnancythe underlying neurobiology remains poorly understood, in part because of the difficulty modeling these behaviors at the laboratory.
The team designed a experiment To measure similar behaviors to anxiety by food in pregnant mice, which have episodes similar to those cravings in humans, with a preference for sugary drinks and excessive consumption of palatable foods.
The brain of gestating female mice undergoes changes in the functional connections of reward circuits, as well as taste and sensorimotor centers, according to the research.
Dopamine, engine of craving
The team looked at the mesolimbic pathwayone of the signal transmission routes of neurons dopaminérgicas. Dopamine is a key neurotransmitter in behaviors of motivation or desire.
The researchers observed that dopamine levels and the activity of its D2R receptor, increased in the nucleus accumbens, a brain region involved in reward circuit.
The alteration of D2R neuronal cells would be responsible for the appearance of cravingssince anxiety about food, typical of pregnancy, disappeared after blocking its activity.
In addition, the team used mice in which they induced a psychological pregnancy, in which there is no embryo growth, but there are physiological changes typical of pregnancy, such as an increase in female sex hormones, says Haddad-Tóvolli.
In those animals they saw “a similar increase in cravings in real pregnancies, showing that the cravings typical of pregnancy do not arise directly to support the development of the embryo,” he says.
Another effect of cravings for high-energy foods, when they are persistent -Hadad-Tóvoli points out- is that “they are enough to create a vulnerability in offspring to metabolic disturbances and anxiety in adulthood, as well as an increased predisposition to develop eating disorders during adolescence.
The rodent pups with that craving problem had, compared to the control group, higher body weight and were more likely to develop behaviors similar to the anxiety and Eating Disorders during adulthood. Male mice were more likely than females.
Although the test has been carried out with animals, Haddad-Tóvolli states that, since the sistema dopaminérgico during evolution it has been conserved between different species, it can be “inferred that similar alterations must occur in humans”.
For this reason, she considers that the results of this study should serve to achieve greater awareness of cravings during pregnancy.
As to whether the changes in the brain that give rise to cravings may have some purpose in favor of pregnancy, the scientist says that there is speculation about it.
Positive or negative for pregnancy?
Evolutionarily, these alterations could occur for ensure energy to support the baby’s development in times of scarcity, but “in our current way of life, with constant exposure to high-energy foods, recurrent cravings end up harming the metabolic and psychological health of the mother, as well as the embryo”.
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There are also environmental factors (such as a diet high in fat and sugars) and metabolic disturbances (such as eating disorders and obesity) that can also alter eating patterns and increase episodes of cravings.
However, the scientist comments, “it is not known whether these factors end up altering the brain in the same way as pregnancy, that is yet to be elucidated.”