Early protein restriction in rats induces anhedonia in adult offspring: A key role of BDNF-TrkB signaling in the nucleus accumbens shell

Clinical evidence suggests that early malnutrition promotes symptoms related to psychiatric disorders later in life. Nevertheless, the molecular mechanisms underpinning nutritional injury induce depression remains unknown. The purpose of the present study was to evaluate whether perinatal protein restriction increases vulnerability to developing depressive-like behavior in adulthood by focusing on anhedonia, a core symptom of depression. To this, male adult Wistar rats submitted to a protein restriction schedule at perinatal age (PR-rats), were subjected to the sucrose preference test (SPT), the novel object recognition test (NORT), the forced swim test (FST), and the elevated plus maze (EPM), and compared to animals fed with a normoprotein diet. To investigate neurobiological substrates linked to early protein undernutrition-facilitated depressive-like behavior, we assessed the levels of brain-derived neurotrophic factor (BDNF) and its receptor TrkB in the nucleus accumbens (NAc), and evaluated the reversal of anhedonic-like behavior by infusing ANA-12. We found that early malnutrition decreased sucrose preference, impaired performance in the NORT and increased immobility time in the FST. Furthermore, perinatal protein-restriction-induced anhedonia correlated with increased BDNF and p-TrkB protein levels in the NAc, a core structure in the reward circuit linked with anhedonia. Finally, bilateral infusion of the TrkB antagonist ANA-12 into the NAc shell ameliorated a reduced sucrose preference in the PR-rats.

Altogether, these findings revealed that protein restriction during pregnancy and lactation facilitates depressive-like behavior later in life and may increase the risk of developing anhedonia by altering BDNF-TrkB in the NAc shell.