Molecular Neuroscience5-HT1A receptor activation: short-term effects on the mRNA expression of the 5-HT1A receptor and galanin in the raphe nucleiRazani, Haleh1; Hedlund, Peter B.1; Hansson, Anita C.1; Fuxe, Kjell1; Ögren, Sven Ove1,2Author Information 1Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden 2Corresponding Author: Sven Ove Ögren Received 8 July 1997; accepted 8 August 1997 NeuroReport: November 10th, 1997 - Volume 8 - Issue 16 - p 3565-3569 Buy Abstract SYSTEMIC adminstration of the 5-HT1A receptor agonist 8-OH-2-(di-n-propylamino)-tetralin (8-OH-DPAT; 0.3 mg/kg, s.c.) was used to explore the effects of activation of 5-HT1A receptors on expression of mRNA coding for 5-HT1A receptor, tryptophan hydroxylase (TPH) and galanin in the ascending raphe nuclei. 8-OH-DPAT increased the hybridization signal of the 5-HT1A receptor by 105% in the dorsal raphe nucleus (B7) 30 min after the injection. No effects were seen at the later time points (2–8 h). In the median raphe nucleus (B8) and the B9 cell group in the medial lemniscus, 8-OH-DPAT induced a marked decrease in labeling 30 min after injection. At 8 h following 8-OH-DPAT injection, the effect had shifted to an increase in 5-HT1A receptor labeling by 68% in the B8 area. Importantly 8-OH-DPAT had no significant effects on the expression of mRNA coding for TPH and galanin. The results suggest an important and differential mechanism for the regulation of 5-HT1A receptor mRNA levels in the dorsal and median raphe nuclei. This regulation may be of importance for the differential control of the activity of the ascending 5-HT neurons, and hence for mood regulation. The results also indicate a dissociation between the effects mediated by 5-HT1A receptor functions and those regulating the coexisting peptide galanin in the dorsal raphe. © Lippincott-Raven Publishers.