Long-term estrogen replacement in rats without ovaries reduces eating and increases activity in the brain’s body clock area during daylight

Chronic oestrogen replacement significantly reduced food intake during the light phase in ovariectomised rats.

• Food intake relative to body weight was significantly lower in the oestrogen group compared to the vehicle group during the light phase.
• No differences in food intake were observed between the groups during the dark phase.
• c-Fos expression in the suprachiasmatic nucleus was significantly higher in the oestrogen group than in the vehicle group during the early light phase.
• No differences in c-Fos expression were noted between the groups during the early dark phase.
• The findings suggest that chronic oestrogen replacement may enhance suprachiasmatic nucleus activity, particularly during the light phase.

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