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Visualization of histamine binding to nuclei.
P Bagavandoss1, M A Mitchell, J W Wilks
1Cancer and Infectious Diseases Research, Upjohn Laboratories, Kalamazoo, Michigan 49001.
Summary
Histamine binds to ovarian cell membranes and nuclei. Antihistamines like pyrilamine block membrane binding, directing histamine to cell nuclei, suggesting novel nuclear roles.
Area of Science:
- Reproductive biology
- Cell biology
- Pharmacology
Background:
- Histamine is a biogenic amine involved in various physiological processes.
- Histamine receptors are known to be present on various cell types, including endothelial and ovarian cells.
- The precise localization and function of histamine binding sites within ovarian cells are not fully understood.
Purpose of the Study:
- To investigate the localization of histamine binding sites in cultured microvascular endothelial cells and ovarian tissue.
- To determine the effect of specific histamine receptor antagonists on histamine binding patterns.
Main Methods:
- Utilized fluorescein-albumin-histamine conjugate for visualizing histamine binding.
- Examined binding patterns in cultured microvascular endothelial cells and glycol methacrylate embedded ovarian tissue sections.
- Assessed the impact of cimetidine and pyrilamine on histamine binding to plasma membranes and nuclei.
Main Results:
- Histamine conjugate bound to plasma membranes and nuclei of luteal, endothelial, and ovarian stromal cells.
- Cimetidine increased nuclear histamine binding while plasma membrane binding remained.
- Pyrilamine completely inhibited plasma membrane binding, with histamine exclusively binding to nuclei of endothelial, germinal epithelial, granulosa, and stromal cells.
- Nuclei of terminally differentiated luteal cells and oocytes did not show histamine binding.
Conclusions:
- Histamine exhibits distinct binding patterns to ovarian cells, localizing to both plasma membranes and nuclei.
- Histamine receptor antagonists differentially affect histamine distribution, with pyrilamine specifically targeting nuclear binding sites.
- The presence of nuclear histamine binding sites suggests potential novel intracellular functions of histamine within the ovary that warrant further investigation.