Classification and biological distribution of histamine receptor sub-types

Area of Science:

• Pharmacology and Immunology
• Cellular Biology

Background:

• Histamine receptors, specifically H1 and H2, are crucial mediators of histamine's diverse effects.
• Understanding the distribution and classification of these receptors is essential for comprehending physiological and pathological responses.

Purpose of the Study:

• To summarize the distribution and classification of H1 and H2 histamine receptors in mammalian and avian tissues.
• To elucidate the cellular mechanisms and physiological roles of histamine receptor activation.

Main Methods:

• Review and summarization of existing data on histamine receptor distribution (Tables 1-4).
• Pharmacological characterization of H1 (mepyramine-sensitive) and H2 (mepyramine-resistant, burimamide/metiamide-sensitive) receptors.
• Investigation of the adenylcyclase system's involvement in H2 receptor-mediated responses.

Main Results:

• H1 and H2 receptors are found on diverse cell types, with proportions varying by species and cell source.
• H2 receptor activation involves the adenylcyclase system, increasing intracellular cyclic-AMP levels.
• H2 receptor-mediated effects include cardiac stimulation, gastric acid secretion, and modulation of immune cell activity.

Conclusions:

• H1 and H2 receptors are widely distributed across multiple organ systems (gastrointestinal, reproductive, respiratory, cardiovascular, nervous) and immune cells.
• These receptors play significant roles in physiological, immunological, and immunopathological processes, including inflammation, allergy, and anaphylaxis.
• Histamine receptor interactions modulate immune competence and the development of immunity.