The role of spinally located dopamine D2 receptors in the regulation of the blood glucose level in mice

• Published in: Pharmacological reports Vol. 72; no. 6; pp. 1666 - 1675
• Main Authors: Hong, JaeSeung, Feng, JingHui, Lee, JinKoo, Lee, HeeJung, Sim, YunBeom, Park, JungSeok, Suh, HongWon
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.12.2020
• Subjects: Drug Safety and Pharmacovigilance; Medicine; Pharmacotherapy; Pharmacy; Blood glucose; Dopaminergic receptors; Corticosterone; Insulin; Intrathecal; Pertussis toxin
• ISSN: 1734-1140; 2299-5684
• DOI: 10.1007/s43440-020-00126-x

Background The possible role of dopamine D 2 receptors located in the spinal cord in the regulation of the blood glucose level have not been investigated before. Methods In the present study, the effect of D 2 receptor agonist and antagonist administered intrathecal ( it ) injection on the blood glucose level were examined in the Institute of Cancer Research (ICR) mice. Results We found that it injection with carmoxirole (D 2 receptor agonist) caused an elevation of the blood glucose level in a dose-dependent manner. Carmoxirole-induced increase of the blood glucose was significantly attenuated by L-741,626 (D 2 receptor antagonist). Previously, we indicated that intrathecal ( it ) treatment with 0.1 μg/5 μl pertussis toxin (PTX, a G i /G o inhibitor) produces a hypoglycemic effect in ICR in a long-term manner. In the present study, it pretreatment with PTX for 6 days almost abolished the hyperglycemic effect induced by carmoxirole. The plasma insulin level was elevated by carmoxirole, and L-741,626 or PTX pretreatment reduced carmoxirole-induced increment of the insulin level. In addition, the plasma corticosterone level was increased by carmoxirole but it pretreatment with L-741,626 or PTX did not affect carmoxirole-induced increment of the corticosterone level. Conclusion Our results suggest that D 2 receptors located in the spinal cord play an important role in the elevation of the blood glucose level. Spinally located inhibitory G-proteins appear to be involved in hyperglycemic effect induced by carmoxirole. Graphic abstract