Phenylethanolamine N-Methyl Transferase Expression in Mouse Thymus and Spleen

• Published in: Brain, behavior, and immunity Vol. 16; no. 4; pp. 493 - 499
• Main Authors: Warthan, Michelle D., Freeman, Jessica G., Loesser, Kathryn E., Lewis, Carolene W., Hong, Min, Conway, Carolyn M., Stewart, Jennifer K.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.08.2002
• Subjects: Age Factors; Animals; Animals, Outbred Strains; catecholamines; Cerebral Cortex - enzymology; epinephrine; Epinephrine - biosynthesis; Gene Expression Regulation, Enzymologic - immunology; In Situ Hybridization; Key Words: PNMT; LY134046; lymphocytes; Medulla Oblongata - enzymology; Mice; Mice, Inbred ICR; neuroimmunology; Neuroimmunomodulation - physiology; Phenylethanolamine N-Methyltransferase - genetics; RNA, Messenger - analysis; spleen; Spleen - enzymology; thymus; Thymus Gland - enzymology; thymus; catecholamines; neuroimmunology; lymphocytes; spleen; Key Words: PNMT; epinephrine
• ISSN: 0889-1591; 1090-2139
• DOI: 10.1006/brbi.2001.0637

Catecholamines usually are found in neurons and chromaffin cells of mammals. In this study, surprisingly high levels of the epinephrine synthesizing enzyme phenylethanolamine N-methyl transferase (PNMT) were detected in the thymus of young mice. Levels of PNMT activity in the thymus were comparable to levels in the brainstem and were suppressed by the PNMT inhibitor LY134046. PNMT mRNA was localized with in situ hybridization throughout the thymus, but levels were approximately twofold higher in the cortex than in the medulla. PNMT activity was barely detectable in the spleen, and only a few cells expressing PNMT mRNA were located in the marginal zone of the white pulp. These findings suggest that cells in the thymus of young mice have the ability to synthesize epinephrine.