Autoradiographic characterization of [3H]-5-HT-moduline binding sites in rodent brain and their relationship to 5-HT1B receptors

AUTOR(ES)

Cloëz-Tayarani, Isabelle

FONTE

The National Academy of Sciences of the USA

RESUMO

5-HT-moduline is an endogenous tetrapeptide [Leu-Ser-Ala-Leu (LSAL)] that was first isolated from bovine brain tissue. To understand the physiological role of this tetrapeptide, we studied the localization of 5-HT-moduline binding sites in rat and mouse brains. Quantitative data obtained with a gaseous detector of β-particles (β-imager) indicated that [3H]-5-HT-moduline bound specifically to rat brain sections with high affinity (Kd = 0.77 nM and Bmax = 0.26 dpm/mm2). Using film autoradiography in parallel, we found that 5-HT-moduline binding sites were expressed in a variety of rat and mouse brain structures. In 5-HT1B receptor knock-out mice, the specific binding of [3H]-5-HT-moduline was not different from background labeling, indicating that 5-HT-moduline targets are exclusively located on the 5-HT1B receptors. Although the distribution of 5-HT-moduline binding sites was similar to that of 5-HT1B receptors, they did not overlap totally. Differences in distribution patterns were found in regions containing either high levels of 5-HT1B receptors such as globus pallidus and subiculum that were poorly labeled or in other regions such as dentate gyrus of hippocampus and cortex where the relative density of 5-HT-moduline binding sites was higher than that of 5-HT1B receptors. In conclusion, our data, based on autoradiographic localization, indicate that 5-HT-moduline targets are located on 5-HT1B receptors present both on 5-HT afferents and postsynaptic neurons. By interacting specifically with 5-HT1B receptors, this tetrapeptide may play a pivotal role in pathological states such as stress that involves the dysfunction of 5-HT neurotransmission.

Documentos Relacionados

• Arterial expression of 5-HT2B and 5-HT1B receptors during development of DOCA-salt hypertension
• Quantitative autoradiographic localization of [3H]imipramine binding sites in the brain of the rat: relationship to ascending 5-hydroxytryptamine neuron systems.
• Provocação social e comportamento agressivo : envolvimento dos receptores 5-HT1A e 5-HT1B no córtex pré-frontal
• Autoradiographic localization of relaxin binding sites in rat brain.
• Effect of 5-HT1B receptor agonists injected into the prefrontal cortex on maternal aggression in rats