Increase in neuropeptide Y activity impairs social behaviour in association with glutamatergic dysregulation in diabetic mice.

BACKGROUND AND PURPOSE Patients with diabetes mellitus are reported to show a raised prevalence of mental disorders, which may be reflected in impaired social interaction. However, the mechanisms underlying such impairment in diabetes are unknown. EXPERIMENTAL APPROACH The present study investigated whether social interaction is impaired in diabetic mice and whether central neuropeptide Y (NPY) and glutamatergic function are involved in such impairment. KEY RESULTS In the three-chamber test, social novelty preference, but not sociability, was impaired in streptozotocin (STZ)-induced diabetic mice. The mRNA level of NPY in the hypothalamus was increased in STZ-induced diabetic mice. Injection of the NPY Y2 receptor agonist NPY 13-36 into naive mice impaired social novelty preference, but not sociability, and this effect was inhibited by the NPY Y2 receptor antagonist BIIE 0246. BIIE 0246 also reversed the impairment of social novelty preference in STZ-induced diabetic mice. Similarly, injection of the AMPA receptor agonist AMPA into naive mice impaired social novelty preference, but not sociability, and this effect was inhibited by the AMPA receptor antagonist NBQX. Impairment of social novelty preference induced by NPY 13-36 was inhibited by NBQX, whereas impairment of social novelty preference induced by AMPA was not inhibited by BIIE 0246. Finally, impairment of social novelty preference in STZ-induced diabetic mice was reversed by NBQX. CONCLUSION AND IMPLICATIONS These findings suggest that NPY neurons are activated in diabetic mice and that this may impair social novelty preference by promoting glutamatergic function through NPY Y2 receptors.