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. 1998 Jan 20;95(2):741–746. doi: 10.1073/pnas.95.2.741

Figure 2.

Figure 2

A schematic drawing of the rat brain in sagittal section demonstrating a neuroanatomical model of leptin action. Circulating leptin acts on cell groups containing leptin receptors (OBRs) within the arcuate (Arc), dorsomedial (DMH), and ventromedial (VMH) hypothalamic nuclei. Ultimately, activation of the autonomic and neuroendocrine components of the paraventricular hypothalamic nucleus (PVH) is responsible for the physiological effects of leptin. We hypothesize that intravenous leptin inhibits Arc neuropeptide Y (NPY) neurons that innervate the PVH. Simultaneously, circulating leptin activates neurons in the DMH whose efferent projections converge on PVH neurons that innervate sympathetic and parasympathetic preganglionic neurons in the medulla and spinal cord. Additionally, circulating leptin activates neurons in the VMH whose efferent projections converge on the anterior hypothalamic area/subparaventricular zone (AHA/SPVZ). The AHA/SPVZ also receives dense innervation from the suprachiasmatic nucleus (SCN). Engagement of these parallel pathways is responsible for the manifestation of the physiological effects of circulating leptin.