Electrical Stimulation of the Lateral Part of the Dorsal Parabrachial Nucleus Causes Hyperglycemia

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Neurons containing CCK-8-like immunoreactive substance are present in the lateral part of the dorsal parabrachial nucleus (PBD) and project fibers to the ventromedial hypothalamus (VMH). The role of these neurons was examined by studies on the effect of electrical stimulation of the lateral part of the PBD on glucose metabolism in female Sprague-Dawley rats in the light and dark periods. PBD stimulation caused hyperglycemia, and the response was greater in the light period than in the dark. PBD stimulation also induced hypoinsulinemia and hyperglucagonemia, but only the hyperglucagonemic response differed in the light and dark periods like the hyperglycemic response. Thus the neural fibers from the PBD to the VMH may be involved in regulation of glucose metabolism by relaying messages to the VMH to control the reciprocal secretions of insulin and glucagon from the pancreas. Possible reasons why the hyperglycemic response to PBD stimulation was greater in the light period are discussed.