Diurnal and seasonal regulation of brain mu-opioid and dopamine D2 receptor signalling in humans
Purpose: Rhythmic regulation of human neurotransmission systems, particularly the mu-opioid receptor (MOR) and dopamine D2 receptor (D2R) signaling, remains poorly understood. Although prior studies indicate possible diurnal fluctuations in D2R signaling, potential existence of diurnal rhythms in MOR signaling has yet to be investigated. Furthermore, whether and how seasonal factors may override…
A recent study has uncovered the diurnal and seasonal regulation of brain mu-opioid receptor (MOR) and dopamine D2 receptor (D2R) signaling in humans. The research, which analyzed PET scans of 372 healthy individuals taken at different times of day and across various seasons, reveals that MOR availability is higher in the morning while D2R availability is higher in the afternoon.
This pattern is consistent across several brain regions, including the anterior cingulate, dorsomedial, and dorsolateral prefrontal cortex, the insula, and the striatum.
Interestingly, the study also found that this diurnal variation in MOR availability is sensitive to an individual's trait-anxiety levels. This suggests that both the MOR system and behavioral traits like anxiety are subject to rhythmic regulation. The findings may have implications for developing interventions that take into account these temporal dynamics, potentially improving mood regulation models.
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