Histamine-induced hyperphosphatemia and hypocalcemia in the laying hen

Area of Science:

• Animal Physiology
• Nutritional Biochemistry
• Avian Endocrinology

Background:

• Histamine plays a role in physiological processes.
• Egg formation in laying hens involves complex mineral regulation.
• Plasma inorganic phosphorus (Pi) and calcium are critical for eggshell calcification.

Purpose of the Study:

• To investigate the impact of histamine on plasma inorganic phosphorus (Pi) and total calcium in laying hens.
• To determine how histamine influences mineral levels during different stages of egg formation.
• To evaluate the efficacy of cimetidine and promethazine in modulating histamine's effects on these minerals.

Main Methods:

• Administering histamine to laying hens during egg formation and in non-laying controls.
• Measuring plasma inorganic phosphorus (Pi) and total calcium levels.
• Utilizing histamine receptor antagonists (cimetidine and promethazine) to assess inhibitory effects.

Main Results:

• Histamine administration led to hyperphosphatemia (elevated Pi) and hypocalcemia (lowered calcium) in laying hens.
• The most significant hypocalcemia occurred during early egg formation stages, with slight hypocalcemia during eggshell calcification.
• Histamine-induced hyperphosphatemia was fully blocked by cimetidine and partially by promethazine.
• Histamine-induced hypocalcemia was completely inhibited by both cimetidine and promethazine.

Conclusions:

• Histamine significantly alters plasma Pi and calcium levels in laying hens, particularly during egg formation.
• The histamine-induced changes in mineral metabolism are stage-dependent during the reproductive cycle.
• Cimetidine and promethazine demonstrate differential effectiveness in blocking histamine's effects on phosphorus and calcium regulation, with both fully inhibiting hypocalcemia.