Elevated serotonin coordinates mammary metabolism in dairy cows

Area of Science:

• Animal Science
• Biochemistry
• Dairy Science

Background:

• Serotonin influences maternal and mammary metabolism.
• Dairy cow research indicates serotonin improves calcium homeostasis.
• The peri-partum dairy cow experiences significant metabolic shifts.

Purpose of the Study:

• To determine how 5-hydroxy-l-tryptophan (5-HTP) administration affects serotonin and calcium metabolism in lactating dairy cows.
• To investigate the impact of 5-HTP on circulating serotonin and blood calcium levels.
• To analyze changes in mammary tissue and milk composition following 5-HTP infusion.

Main Methods:

• Intravenous infusion of 5-HTP (1.5 mg/kg) or saline in 12 multiparous dairy cows over 3 days.
• Collection of daily milk samples and blood samples pre- and post-infusion.
• Mammary biopsies and blood sampling at 48, 56, and 72 hours post-infusion.

Main Results:

• 5-HTP infusion increased circulating serotonin concentrations and caused transient hypocalcemia.
• Milk calcium concentrations and ORAI1 mRNA/protein levels in mammary tissue were elevated post-5-HTP.
• Parathyroid hormone-related protein mRNA and mammary serotonin content increased 56 hours after infusion.

Conclusions:

• 5-HTP administration effectively increases serotonin levels in lactating dairy cows.
• Serotonin precursor (5-HTP) influences both systemic and mammary calcium metabolism.
• Findings suggest a role for 5-HTP in modulating endocrine and autocrine/paracrine pathways in dairy cows.