Activation of ventral pallidum-projecting neurons in the nucleus accumbens via 5-HT receptor stimulation regulates motivation for wheel running in male mice.

Rodents have a strong motivation for wheel running; however, the neural mechanisms that regulate their motivation remain unknown. We investigated the possible involvement of serotonin (5-HT) systems in regulating motivation for wheel running in male mice. Systemic administration of a 5-HT receptor antagonist (WAY100635) increased the number of wheel rotations, whereas administration of a 5-HT or 5-HT receptor antagonist (volinanserin or SB242084, respectively) decreased it.

Social defeat stress enhances the rewarding effects of cocaine through α adrenoceptors in the medial prefrontal cortex of mice.

Various stressors potentiate the rewarding effects of cocaine and contribute to cocaine cravings. However, it remains unclear whether psychosocial stress enhances the rewarding effects of cocaine. Accordingly, this study employed a cocaine-conditioned place preference (CPP) paradigm combined with social defeat (SD) exposure to investigate the effects of acute SD stress on cocaine reward in male mice.

Noradrenergic stimulation of α adrenoceptors in the medial prefrontal cortex mediates acute stress-induced facilitation of seizures in mice.

Stress is one of the critical facilitators for seizure induction in patients with epilepsy. However, the neural mechanisms underlying this facilitation remain poorly understood. Here, we investigated whether noradrenaline (NA) transmission enhanced by stress exposure facilitates the induction of medial prefrontal cortex (mPFC)-originated seizures.

Median raphe serotonergic neurons projecting to the interpeduncular nucleus control preference and aversion.

Appropriate processing of reward and aversive information is essential for survival. Although a critical role of serotonergic neurons in the dorsal raphe nucleus (DRN) in reward processing has been shown, the lack of rewarding effects with selective serotonin reuptake inhibitors (SSRIs) implies the presence of a discrete serotonergic system playing an opposite role to the DRN in the processing of reward and aversive stimuli. Here, we demonstrated that serotonergic neurons in the median raphe nucleus (MRN) of mice process reward and aversive information in opposite directions to DRN serotonergic neurons.

A spatiotemporal increase of neuronal activity accompanies the motivational effect of wheel running in mice.

Spatiotemporal patterns of neuronal activity underlying the motivational effect of rotating running wheels (RWs) in rodents remain largely undetermined. Here, we investigated changes of neuronal activity among brain regions associated with motivation across different intensities of motivation for RWs in mice. Daily exposure to RWs gradually increased rotation number, then became stable after approximately 3 weeks.