Co-localization of 5-HT1B- and 5-HT1D receptor mRNA in serotonergic cell bodies in guinea pig dorsal raphé nucleus: a double labeling in situ hybridization histochemistry study.

In order to provide further details on the cellular localization of 5-HT1B- and 5-HT1D receptor mRNA in the dorsal raphé nucleus, we performed, in the same sections of guinea-pig dorsal raphé nucleus, double labeling in situ hybridization histochemistry for: (1) 5-HT1B receptor mRNA and 5-HT1D receptor mRNA, (2) 5-HT1B receptor mRNA and 5-HT transporter (5-HTT) mRNA as marker for serotonergic neurons and (3) 5-HT1D receptor mRNA and 5-HTT mRNA. The 5-HT1B receptor mRNA was present in all cells containing 5-HT1D receptor mRNA. Similarly, both 5-HT1B- and 5-HT1D receptor mRNA was present in all 5-HTT mRNA positive cells. The present study demonstrates that 5-HT1B- and 5-HT1D receptor mRNA is co-localized in serotonergic cell bodies of the guinea pig dorsal raphé nucleus.