PMID- 14642449 OWN - NLM STAT- MEDLINE DCOM- 20040210 LR - 20190614 IS - 0006-8993 (Print) IS - 0006-8993 (Linking) VI - 994 IP - 1 DP - 2003 Dec 19 TI - Circadian variations in expression of the trkB receptor in adult rat hippocampus. PG - 67-72 AB - The expression of brain-derived neurotrophic factor (BDNF) in the central nervous system (CNS) and the expression of its high-affinity trkB receptor on neuron surfaces are known to depend on neuron activity. The expression of BDNF (mRNA and protein) and trkB mRNA shows circadian oscillations in rat hippocampal homogenates. We investigated circadian variations in trkB expression in specific areas of the adult rat hippocampal formation by immunohistochemistry. In sets of two experiments performed in the spring, 39 2-month-old male Wistar rats were accustomed to a 12-h light-12-h dark cycle for 2 weeks. Three animals were then sacrificed every 4 h. Forty-micrometer-thick coronal sections of hippocampal formation were obtained and processed for trkB immunohistochemistry. Cell staining intensity was assessed by image analysis of different hippocampal areas on five sections per animal. Circadian rhythmicity was evaluated by the cosinor method. Statistically significant circadian variations in trkB expression were found in dentate gyrus, entorhinal cortex, and the CA3 and hilar regions of the hippocampus, with highest expression during the first half of the dark (activity) period. These findings suggest a relationship between trkB expression and the physiological neuronal activation of wakefulness. TrkB receptor expression in the hippocampal regions studied was continuous and changes were gradual over the 24-h cycle, suggesting that more complex regulatory mechanisms also intervened. FAU - Dolci, Claudia AU - Dolci C AD - Dipartimento di Anatomia Umana, Universita di Milano, Via Mangiagalli 31, Milan I-20133, Italy. claudia.dolci@unimi.it FAU - Montaruli, Angela AU - Montaruli A FAU - Roveda, Eliana AU - Roveda E FAU - Barajon, Isabella AU - Barajon I FAU - Vizzotto, Laura AU - Vizzotto L FAU - Grassi Zucconi, Gigliola AU - Grassi Zucconi G FAU - Carandente, Franca AU - Carandente F LA - eng PT - Comparative Study PT - Journal Article PL - Netherlands TA - Brain Res JT - Brain research JID - 0045503 RN - 0 (RNA, Messenger) RN - EC 2.7.10.1 (Receptor, trkB) SB - IM MH - Animals MH - Circadian Rhythm/*physiology MH - Gene Expression Regulation/*physiology MH - Hippocampus/*metabolism MH - Male MH - RNA, Messenger/biosynthesis/genetics MH - Rats MH - Rats, Wistar MH - Receptor, trkB/*analysis/*biosynthesis/genetics EDAT- 2003/12/04 05:00 MHDA- 2004/02/11 05:00 CRDT- 2003/12/04 05:00 PHST- 2003/12/04 05:00 [pubmed] PHST- 2004/02/11 05:00 [medline] PHST- 2003/12/04 05:00 [entrez] AID - S0006899303037387 [pii] AID - 10.1016/j.brainres.2003.09.018 [doi] PST - ppublish SO - Brain Res. 2003 Dec 19;994(1):67-72. doi: 10.1016/j.brainres.2003.09.018.