Combination of immunohistochemical and in situ hybridization methods to reveal tyrosine hydroxylase and oxytocin and vasopressin mRNAs in magnocellular neurons of obese Zucker rats

Co-localization of chemical messengers in the same neuron is linked to neurochemical plasticity and has been studied extensively [B. Meister. M.J. Villar, S. Ceccatelli, T. Hokfelt, Localization of chemical messengers in magnocellular neurons of the hypothalamic supraoptic and paraventricular nuclei: an immunohistochemical study using experimental manipulation, Neuroscience 37 (1900) 603-633; B. Meister, R. Cortes, M.J. Villar, M. Schalling, T. Hakfelt, Peptides and transmitter enzymes in hypothalamic magnocellular neurons after administration of hyperosmotic stimuli: comparison between messenger RNA and peptide/protein levels, Cell Tissue Res. 260 (1990) 279-297]. Obese Zucker rats display an example of such a phenomenon expressing an enzyme of catecholamine synthesis-tyrosine hydroxylase (TH)-in magnocellular neurons (MCN) of supraoptic and paraventricular nuclei of hypothalamus [S. Fetissov, F. Marsais, S. Nicolaidis, A. Calas, Expression of tyrosine hydroxylase in magnocellular hypothalamic neurons of obese (fa/fa) and lean heterozygous (Fa/fa) Zucker rats, Mol. Brain Res. 50 (1997) 314-318]. To understand the biological role of TH in MCN of obese Zucker rat, we studied TH expression in relation to the vasopressinergic and oxytocinergic neurons. We present a protocol of double labelling including immunohistochemical for TH and in situ hybridization for OT and VP mRNA. The described protocol can be applied for detection of co-localized expressions of a broad range of chemical brain messengers and proteins. (C) 1999 Elsevier Science B.V. All rights reserved.