by -- A. Agrawal, PhD
Updated: Feb 25th 2010

THURSDAY, Feb. 25 (HealthDay News) -- Mice lacking a dopamine receptor have an impaired insulin response and glucose intolerance, which may explain why certain neuroleptic drugs that block this receptor cause hyperinsulinemia or diabetes, according to a study published online Feb. 10 in Endocrinology.

Noting that neuroleptic drugs that block the dopamine D2 receptor (D2R) cause hyperinsulinemia or diabetes, Isabel García-Tornadú, Ph.D., of Consejo Nacional de Investigaciones Científicas y Técnicas in Buenos Aires, Argentina, and colleagues studied glucose homeostasis in mice lacking the D2R.

The researchers found that the mice had an impaired insulin response to glucose and were glucose intolerant due to a blunted insulin secretory response. Treatment with cabergoline, a dopamine agonist, led to an impaired insulin response to glucose and glucose intolerance in normal mice but not mice lacking the D2R. Treatment with haloperidol, a D2R antagonist, could partially prevent this effect. Mice lacking the D2R had fewer pancreatic β-cells as adults and reduced β-cell replication at 2 months of age.

"Pancreatic D2Rs inhibit glucose-stimulated insulin release," the authors conclude. "Our finding that the D2R plays an essential role in β-cell proliferation and insulin secretion adds a novel participant to the list of growth factors and hormones that control the fundamental and multifactorial process of glucose homeostasis."

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