Short photoperiod-induced decrease of histamine H3 receptors facilitates activation of hypothalamic neurons in the...

Area of Science:

• Neuroscience
• Physiology
• Chronobiology

Background:

• Seasonal mammals exhibit adaptive physiological changes to survive winter, including body weight reduction.
• The specific hypothalamic neuronal mechanisms driving these seasonal adaptations remain largely unknown.

Purpose of the Study:

• To investigate the hypothalamic neuronal events underlying photoperiod-induced seasonal adaptation in Siberian hamsters.
• To identify the role of the dorsomedial region of the arcuate nucleus (dmpARC) and histamine H3 receptors in seasonal body weight changes.

Main Methods:

• Electrophysiological patch-clamping recordings in Siberian hamsters exposed to different photoperiods.
• Assessment of neuronal activity using c-Fos expression.
• Histamine H3 receptor antagonist application.
• Trans-synaptic retrograde tracing to map neuronal pathways to adipose tissue.

Main Results:

• Short-day photoperiods significantly increased neuronal activity in the dmpARC.
• This increase in dmpARC activity was dependent on photoperiod-driven down-regulation of histamine H3 receptor expression.
• Activation of dmpARC neurons was linked to sympathetic outflow to white adipose tissue.

Conclusions:

• Increased dmpARC neuronal activity, modulated by histamine H3 receptor down-regulation, plays a crucial role in the physiological adaptation of body weight regulation during seasonal photoperiod changes.
• The dmpARC serves as a key integration center for photoperiodic information influencing energy balance.