Meal characteristics and individual responsiveness may impact digestive sensations occurring before, during and after a meal. However, the neural mechanisms driving subjective responses to the ingestion of a palatable meal have been subject to limited study.
A new brain imaging study, led by Emeran A. Mayer from the G. Oppenheimer Center for Neurobiology of Stress and Resilience at the University of California, Los Angeles, has found that sex may affect subjective responses to a palatable meal at the thalamus and anterior insula level in healthy individuals.
The researchers recruited 40 healthy adult women and men who underwent resting-state magnetic resonance imaging before and after ingesting a palatable meal. Thalamic and insular connectivity were evaluated through magnetic resonance imaging, while self-perception of satiety and digestive well-being was registered using scales.
Commonalities in the impact of meal ingestion in women and men included a postprandial decrease in connectivity between insula and sensorimotor and prefrontal cortices in both sexes. In contrast, the thalamus, a relay station for sensory information, showed an increased connectivity with insular, frontal and occipital cortices, with anterior insula registering a conscious sensation of palatability, hunger and satiation. Altogether, the results show a response in brain activity and meal-related sensations after ingesting a palatable meal that are common to both women and men.
Differences in sensory responses to meal ingestion were also apparent. Reductions in anterior insular connectivity related to greater satiety and well-being were found in men but not in women, in agreement with previous findings. Patterns in the thalamus were opposite to those of the anterior insula. The women under study showed increased thalamic connectivity, which was related to changes in meal-related sensations including satiety and digestive well-being. Simply put, women experienced more satiety and satisfaction after the palatable meal compared to men.
On the whole, the findings show sex specific differences in brain activity and subjective meal-related satiety and digestive well-being after the ingestion of a palatable meal. Thus, there is a strong chance that sex should start being considered as an important biological variable in studies exploring postprandial sensations related to meal ingestion.
In that regard, the importance of sex also seems to be important in understanding gut microbiota-host interactions with mental health across lifespan.
This original article belongs to the special issue “Food and Diet for Gut Function and Dysfunction” in the peer reviewed open access journal Nutrients. This issue was instigated by the European Society of Neurogastroenterology and Motility, guest edited by Profs Fernando Azpiroz and Paul Enck, and made possible through an unrestricted educational grant from Danone.
Kilpatrick L, Pribic T, Ciccantelli B, et al. Sex differences and commonalities in the impact of a palatable meal on thalamic and insular connectivity. Nutrients. 2020; 12(6), 1627. doi: 10.3390/nu12061627.