Objectives: 

It has been demonstrated that Galanin (GAL) and the N-terminal Galanin fragment (1-15) [GAL (1-15)] interact specifically with Y1 and Y2 Neuropeptide Y (NPY) receptor agonists in the Nucleus Tractus Solitarii (Díaz-Cabiale et al., Regul Pept. 163:130-136,2010). GAL blocks the cardiovascular responses elicited by Y1 agonists whereas GAL (1-15) modulates exclusively the responses induced by Y2 agonists. Autoradiographical studies show that these interactions take place at receptor level. Furthermore, GAL interacts with Y1 receptor in other areas the arcuate nucleus (nArc), the amygdala (Amyg) and the dorsal raphe nucleus (nRD). The aim of this work is to study if GAL (1-15) modulate the binding of the Y1 receptor agonist [125I]Leu31,Pro34-PYY in the arcuate nucleus (nArc), the amygdala (Amyg) and the dorsal raphe nucleus (nRD), where Y1 and GAL receptors have been described

Materials: 

The binding of [125I]-Leu31-Pro34-PPY (25 pM) was analyzed by receptor autoradiography in the presence of GAL (1-15) at the doses of 0.3nM, 1nM and 3nM. The specific GAL receptor antagonist M40 (1nM) was also used.

Results: 

GAL (1-15) 1nM increased the Y1 agonist binding in the nArc and Amyg by 13% (p<0.01) and by 10% (p<0.05) respectively. In the nRD an increased of 16% was also observed with GAL (1-15) 3nM. In these experiments, M40 was able to block the effects induced by GAL (1-15).

Conclusions: 

These results demonstrate that GAL (1-15) modifies the binding of Y1 agonists in the nArc, the nRD and Amyg of the rat. These results may be of relevance for Y1 mediated actions in the central nervous system. This work has been supported by the Spanish Junta de Andalucia CVI646 and TV3-Marató 090130/31/32.