HISTOLOGY AND HISTOPATHOLOGY

Cellular and Molecular Biology

 

Melatonin-like immunoreactivity in the pineal gland of the cow: an immunohistochemical study

J.C. Carvajal, M.B. Gómez Esteban, S. Carbajo and L. Muñoz-Barragán

Department of Human Anatomy and Histology, Faculty of Medicine, University of Salamanca, Spain

Offprint requests to: Prof. Luciano Muñoz Barragán, Departamento de Anatomía e Histología Humanas, Facultad de Medicina, Universidad de Salamanca, Avenida de Alfonso X el Sabio s/n, 37007 Salamanca, Spain. Fax: 34 923 294687. e-mail: lmunoz@usal.es

Summary. With a view to checking the presence of melatonin in the pineal gland of the cow, in the present work we used six adult animals, ranging in age from one to six years, which were sacrificed at dawn. Sections of 6 µm thickness of Bouin-fixed and paraffin-embedded pineal glands were incubated in an anti-melatonin serum, which was provided by the Institute for Molecular and Cellular Recognition, Gunma University, Maebshi, Japan. After incubation and successive washings in PBS, some of the sections were treated with the avidin-biotin-peroxidase complex (ABC) technique using antisera from Sigma, and developed with the method of Graham and Karnovsky (which employs 3,3’-diaminobenzidine and H2O2 as developer). Other sections were incubated in a goat-anti-rabbit IgG (H+L) bound to fluorochrome Cy5 for immunofluorescence studies. An intense reaction for melatonin was observed in the cytoplasm but not in the nucleus of melatonin secreting pinealocytes located in peripheral and intermediate zones of the pineal gland. Immunoabsorption of the antimelatonin primary antibody with melatonin at a dilution of 10 mM per 0.1 ml of serum prevented the reaction, as happened when any of the antisera used in the procedure were used. Immunoabsorption of anti-melatonin serum with different amounts of bovine albumin (ranging between 1/5 to 1/50) failed to inhibit the immunoreactivity. When a bovine anti-albumin antibody was employed, working with the above methods, no immunoreaction was detected. Our data suggest that the pinealocytes of cows sacrificed at dawn contain immunoreactive melatonin. Histol Histopathol 19, 1187-1192 (2004)

Key words: Cow, Melatonin, Pinealocytes, Immunocytochemical

DOI: 10.14670/HH-19.1187