In the brain, activation of Y1 and Y5 receptors (Y1R, Y5R) for Neuropeptide Y (NPY) reduces anxiety, modulates neuronal excitability, increases food intake and regulates hormone secretion. Additionally, Y1R and Y5R are colocalized in several forebrain regions. To unmask the specific function of each receptor we restricted the functional inactivation of the Y1R gene to Y5R containing neurons in the postnatal brain. By taking advantage of the clustering of the Y1R and the Y5R receptor, which are transcripted in opposite direction by the same promoter, we generated transgenic mice carrying a bidirectional expression module for specific co-expression of a tet-dependent trascription factor (tTA) and the Venus fluorescent protein, under the control of the Y5R and Y1R promoters respectively (TgY5RhtTA/Y1RVenus). By tTA-mediated activation of Cre recombinase (achieved by transgenic mouse line, LC-1) we showed that tTA-directed Cre expression is detectable in several brain regions, including hypothalamus, amygdala and hippocampus. We now generated mice with Y1R conditional gene inactivation in Y5R-expressing neurons by crossing TgY5RhtTA/Y1RVenus/LC-1 mice with TgY1Rlox/lox mice with gene-targeted, modified Y1R alleles. Additionally, to achieve a temporal control of Cre-mediated recombination, doxycycline treatment was applied from conception until birth. In the resulting Y1RY5R-/- mice the induced specific loss of Y1R was visualized by in situ hybridization of adult mouse brains. We analyze Y1RY5R-/- mice for anxious behaviour (by elevated plus maze test) and for feeding behaviour. Both males and females Y1RY5R-/- mice show a lower frequency of entrance and percent of time spent into open arms, as compared to Y1R +/+ mice demonstrating the fundamental importance of Y1R in anxious behaviour. Conversely, conditional depletion of Y1R gene failed to affect body weight and food intake, suggesting a biological redundancy between Y1R and Y5R in the control of feeding behaviour.
Specific NPY-Y1 receptor deletion in Y5R containing neurons impairs anxious behaviour but not feeding behaviour
LONGO, ANGELA;BERTOCCHI, Ilaria;OBERTO, Alessandra;EVA, Carola Eugenia
2008-01-01
Abstract
In the brain, activation of Y1 and Y5 receptors (Y1R, Y5R) for Neuropeptide Y (NPY) reduces anxiety, modulates neuronal excitability, increases food intake and regulates hormone secretion. Additionally, Y1R and Y5R are colocalized in several forebrain regions. To unmask the specific function of each receptor we restricted the functional inactivation of the Y1R gene to Y5R containing neurons in the postnatal brain. By taking advantage of the clustering of the Y1R and the Y5R receptor, which are transcripted in opposite direction by the same promoter, we generated transgenic mice carrying a bidirectional expression module for specific co-expression of a tet-dependent trascription factor (tTA) and the Venus fluorescent protein, under the control of the Y5R and Y1R promoters respectively (TgY5RhtTA/Y1RVenus). By tTA-mediated activation of Cre recombinase (achieved by transgenic mouse line, LC-1) we showed that tTA-directed Cre expression is detectable in several brain regions, including hypothalamus, amygdala and hippocampus. We now generated mice with Y1R conditional gene inactivation in Y5R-expressing neurons by crossing TgY5RhtTA/Y1RVenus/LC-1 mice with TgY1Rlox/lox mice with gene-targeted, modified Y1R alleles. Additionally, to achieve a temporal control of Cre-mediated recombination, doxycycline treatment was applied from conception until birth. In the resulting Y1RY5R-/- mice the induced specific loss of Y1R was visualized by in situ hybridization of adult mouse brains. We analyze Y1RY5R-/- mice for anxious behaviour (by elevated plus maze test) and for feeding behaviour. Both males and females Y1RY5R-/- mice show a lower frequency of entrance and percent of time spent into open arms, as compared to Y1R +/+ mice demonstrating the fundamental importance of Y1R in anxious behaviour. Conversely, conditional depletion of Y1R gene failed to affect body weight and food intake, suggesting a biological redundancy between Y1R and Y5R in the control of feeding behaviour.
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