The present study aimed to evaluate the interaction between the endocannabinoid and dopaminergic system on binge-like intake of PF in mice. To evaluate this, mice were exposed to 12 binge-test sessions to induce binge-like eating and then were evaluated in three additional sessions under treatment with either a DRD4 antagonism alone or in combination with a CB2R agonist or antagonist. Our findings show that the present restricted intermittent access model reliably induces binge-like intake of PF in a non-caloric restriction-dependent manner, which is consistent with studies that suggest that PF consumption increases the risk of development of BED (Sinclair et al., 2015; Chávez-Hernández et al., 2024). Our results show that over 12 sessions of BET, there is a significant increase in binge-like intake episodes, with PF overconsumption escalating from 20 to 40% of total caloric intake, showing the driving of this maladaptive eating behavior.

The DA activity has been implicated in regulating eating behaviors (Gervasini et al., 2018). Furthermore, DRD4 has been identified to be involved in the modulation of the reward process of PF consumption and may contribute to the dysregulation of food intake in patients with eating disorders (Botticelli et al., 2020). Our results demonstrate that the administration of the DRD4 selective antagonists decreased binge-like intake of PF compared to control, which is consistent with other studies that show that the administration of DRD4 antagonists significantly reduced binge episodes (López-Alonso et al., 2023; Cruz-Trujillo et al., 2024), suggesting that this receptor plays a crucial role in facilitating the compulsive nature of binge eating. On the other hand, Yan et al. (2012) show that there was no effect in the administration of DRD4 antagonist in food-seeking behavior in rats in an operant paradigm; this inconsistency with our results may be explained regarding the task used and evaluation conditions. It is important to mention that the downregulation of DRD4 has been identified as a risk factor that may underly binge-purge syndromes in patients (Steiger et al., 2016). Additionally, a relationship between the DRD4 gene polymorphism and environmental influences has been proposed, suggesting that this interaction could play a key role in promoting overeating and weight gain (Botticelli et al., 2020). Together, our findings suggest that DRD4 signaling participates in the regulation of the consumption of PF, as well as the regulation of binge-like intake. Nevertheless, the systematic administration of DRD4 selective antagonists also impaired the memory process, a result that is consistent with previous studies (Miyauchi et al., 2017). In this regard, given our findings on the effect of DRD4 antagonism on memory and binge-like intake reduction, it is important that future studies focus on evaluating and differentiating these effects in relation to food palatability. Further research on the potential role of memory mechanisms, such as memory extinction, could provide valuable insights into how these processes may influence binge-like eating behavior.

One of the key findings of the present study indicates that the combination of DRD4 blockade with CB2 receptor activation induced the greatest reduction in binge eating compared to other treatments. This suggests a functional interaction between the dopaminergic and endocannabinoid systems in the modulation of binge-like eating behavior, potentially through CB2 receptor-mediated modulation of reward pathways to reduce this behavior. Although, initially, CB2R was considered a peripherally expressed receptor, such as in the spleen, leukocytes, testis, and muscle (Onaivi et al., 2012), CB2R activity has also been related to anti-inflammatory properties in both central and peripheral nervous system (García-Gutiérrez et al., 2025). In this regard, CB2R activation in microglial cells is associated with increased expression of anti-inflammatory factors such as IL-10 (Ma et al., 2015). In relation to this, our results show that systematic administration of a CB2R agonist may induce an anti-inflammatory effect. Even though this was not measured in the present study, it is important to determine it in future studies. Moreover, CB2R activity has been shown to reduce weight gain, relieve glucose tolerance, enhance insulin sensitivity, and attenuate inflammation by suppressing macrophage polarization in a mouse model of obesity (Wu et al., 2020). Furthermore, both receptors co-localize, such as neurons in the NAc (Zhang et al., 2014; Cruz-Trujillo et al., 2024). In this regard, studies suggest that CB2R activity participates in addictive behaviors such as cocaine self-administration behavior and sugar consumption by modulation of mesolimbic dopaminergic neurons (Zhang et al., 2017; Bourdy et al., 2021). Furthermore, CB2R activation has been suggested to regulate the reduction of VTA neurons’ excitability, the reduction of intracellular cAMP levels, and the enhancement of the M-type K + channel function (Ma et al., 2019). In this regard, studies have shown that DRD4 antagonists significantly reduced binge episodes (López-Alonso et al., 2023; Cruz-Trujillo et al., 2024) and that CB2R agonist reduces addictive behaviors, such as cocaine self-administration behavior and sugar consumption by modulation of mesolimbic dopaminergic neurons (Zhang et al., 2017; Bourdy et al., 2021; García-Blanco et al., 2023). Additionally, our group recently demonstrated that the administration of CB2R agonists reduces binge-like intake of PF (Rodríguez-Serrano and Chávez-Hernández, 2025). Furthermore, it has been suggested that CB2R are mainly expressed in the postsynapsis (Chen et al., 2017) and that their activity ultimately results in the suppression of neuronal activity. On the other hand, DRD4 has been identified in presynaptic neurons in the NAc, modulating excitatory neurotransmission (Svingos et al., 2000); also, it has been suggested that the stimulation of DRD4 modulates glutamatergic transmission in the NAc, promoting PF consumption (Cruz-Trujillo et al., 2024). Our results demonstrate that the combination of DRD4 antagonism and CB2R agonism effectively reduces binge-like intake of PF, presenting a novel potential therapeutic approach for BED. Furthermore, our results suggest an interaction effect between the blockade of DRD4 and the activation of CB2R.

On the other hand, our results show no significant reduction of binge-like intake by the coadministration of DRD4 antagonists with CB2R antagonists, suggesting that the activity of CB2R is key to reducing this behavior. In this regard, it has been reported that the lack of CB2R may constitute a protective factor, while overexpression may be a vulnerability for the development of food addiction (García-Blanco et al., 2023). Therefore, our results suggest that there is an interaction of DRD4 with CB2R in the regulation of binge eating behaviors. Additionally, results from the food preference test show that coadministration of DRD4 antagonist with either CB2R agonist or antagonist reduces exploration to PF compared to SD (non-significant), suggesting a decreased preference for PF that could be further explored behaviorally in future studies.

The DRD4 has been involved in the pathogenesis of neuropsychiatric diseases (Botticelli et al., 2020; Chestnykh et al., 2023). Therefore, we evaluated the effect of coadministration of DRD4 antagonist with CB2R agonist or antagonist in anxiety-like and depression-like behaviors. Our results show that the coadministration of DRD4 antagonist and CB2R agonist and antagonist reduced the distance traveled in the central and periphery of OFT compared to the CON and VEH groups. It is important to note that studies indicate that the administration of DRD4 antagonists does not produce locomotor alterations (Erlij et al., 2012). In this regard, our findings suggest that the treatments administered reduced anxiety-like behavior, evidenced by a reduction in the distance traveled in both areas of OFT, but this should be further explored in future studies. Furthermore, FST results show no difference between treatments, CON and VEH group, in immobility time, which suggests that the treatments administered did not induce depression-like behaviors. In this regard, it has been shown that the blockade of DRD4 (Basso et al., 2005) and activation of CB2R (Andersen, 2024) do not affect this type of behavior.

In summary, our results show that DRD4 may regulate eating behaviors, given that the administration of DRD4 antagonist decreases binge-like PF. Moreover, the combined effect of DRD4 receptor blockade with CB2 receptor activation produced an even more pronounced reduction in binge eating. These findings suggest an interaction between the dopaminergic and endocannabinoid systems, in which the activation of CB2 receptors further modulates the reward pathways and attenuates binge-like behavior. This mechanism could be further explored in future studies as a potential treatment for BED.