Possible crosstalk between leptin and prolactin during pregnancy

Area of Science:

• Neuroendocrinology
• Reproductive Biology
• Metabolic Regulation

Background:

• Rodents display leptin resistance and elevated prolactin/placental lactogens during pregnancy.
• A potential crosstalk between prolactin and leptin signaling is hypothesized to influence energy balance during gestation.
• It remains unclear if specific neuronal populations co-express receptors for both leptin and prolactin.

Purpose of the Study:

• To identify prolactin-responsive cells expressing the leptin receptor (LepR) in the mouse brain.
• To assess the leptin response in various brain nuclei of pregnant versus nulliparous mice.

Main Methods:

• Utilized a LepR-reporter mouse model (tdTomato fluorescent protein) to visualize LepR-expressing cells.
• Employed immunohistochemistry for phosphorylated signal transducer and activator of transcription-5 (pSTAT5-ir) to identify prolactin-responsive cells.
• Quantified co-localization of tdTomato and pSTAT5-ir in different brain nuclei across various physiological states.

Main Results:

• Significant co-expression of LepR and prolactin-responsive neurons found in the medial preoptic area (MPA), retrochiasmatic area, and nucleus of the solitary tract (NTS).
• Smaller percentages of co-expressing neurons observed in the arcuate nucleus, medial tuberal nucleus, and ventral premammillary nucleus.
• Late pregnant mice showed a diminished leptin response in the MPA and NTS compared to nulliparous controls.

Conclusions:

• The brain integrates leptin and prolactin signaling through co-expressing neuronal populations.
• Findings support the hypothesis that elevated prolactin or placental lactogens during pregnancy can directly impair LepR signaling.
• This interference may contribute to the development of leptin resistance during gestation.