Null-field behavior

Mutant mice lackingNPY showincreased anxiety-relatedbehavior (Palmiter et al. 1998) a full description of the behavioral phenotype of NPY receptor-null mutant mice is not available yet. However, data from Y2 receptor-null mutants support an anti-stress activity of NPY (Tschenett et al. 2003). In addition to the anxiolytic and anti-stress effects of NPY, a relationship to alcohol intake has been described. Voluntary ethanol consumption is increased in NPY and Yi receptor-null mutant mice, whereas either NPY overexpression or potentiation of NPY signaling through blockade of Y2 receptors suppresses rodent alcohol intake (Thiel et al. 1998,2002 Thorsell et al. 2002). Thus, in addition to anxiety and depression, alcohol dependency may be a promising clinical field for newly developed NPY receptor hgands. 

Holmes A, Kinney JW, Wrenn CC, Li Q, Yang RJ, Ma L, Vishwanath J, Saavedra MC, Inner-field CE, Jacoby AS, Shine J, lismaa TP, Crawley JN (2003) Galanin GAL-Rl receptor null mutant mice display increased anxiety-like behavior specific to the elevated plus-maze. Neuropsychopharmacology 28 1031 -1044... 

Specifically, these studies found that 5-HT1A-R null animals showed increased anxiety-like behavior in the open field, elevated plus maze, elevated zero maze, and novel object tests. 5-HT1A-R KOs were also less immobile in the forced swim and tail suspension tests, the same response induced in these tests by antidepressant drugs. However, it is unclear whether this decreased immobility truly reflects an antidepressant-like coping reaction mediated by increased 5-HT transmission or whether it simply reflects an increased stress response in these anxiety-prone mutant mice (12). 

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