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The number of cells expressing dopamine D 2 receptor mRNA in rat brain caudate putamen is higher in oestrus
Author(s) -
Uršič Matjaž,
Bavdek Srdan V.,
Zabavnik Jelka
Publication year - 2003
Publication title -
journal of anatomy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 118
eISSN - 1469-7580
pISSN - 0021-8782
DOI - 10.1046/j.1469-7580.2003.00180.x
Subject(s) - riboprobe , in situ hybridization , dopamine , biology , receptor , messenger rna , endocrinology , medicine , putamen , striatum , biochemistry , gene
Dopamine D 2 receptors (D 2 ‐Rs) in the central nervous system are involved in the control of locomotion, cognition, emotion and neuroendocrine secretion. The intensity of cellular responses to specific stimuli is dependent on the concentration of dopamine or its agonist, and the availability, as well as the concentration, of all the other components of the signalling pathway in the cell, including the receptors. Many factors can influence the level of mRNA encoding the receptors. In order to study the changes in the level of expression of the D 2 ‐R mRNA in the brain of female rats at different stages of the oestrous cycle, we used a quantitative in situ hybridization technique. Four groups of animals were analysed: rats in prooestrus (POE), oestrus (OE), dioestrus 1 (DOE1) and dioestrus 2 (DOE2). A 35 S‐labelled riboprobe was transcribed in vitro from the 1.5‐kb D 2 ‐R cDNA. The caudate putamen of the rats, which shows the highest level of expression of D 2 ‐R mRNA in the brain, was examined. The number of silver grains per cell, representing hybridization of riboprobe, and the number of cells expressing the D 2 ‐R mRNA, were counted with the computer‐assisted image analysis system Lucia‐M. Our results show that the expression of the D 2 ‐R mRNA in the lateral striatum varies during the oestrous cycle, with the highest expression measured during DOE2. The number of cells expressing the D 2 ‐R mRNA also changes during the different phases, with the highest number being detected in OE. This indicates that during OE more cells transcribe the D 2 ‐R mRNA. The results suggest that the variations in the concentration of the D 2 ‐R mRNA in the caudate putamen of the rat brain at different stages of the reproductive cycle are caused by the combination of variable expression of the mRNA per cell and different number of the cells that express the mRNA.