Accessibility of ghrelin into the brain

How is ghrelin transported from the blood to the neurons that mediate its action?

Median eminence of a mouse ICV injected with a fluorescent ghrelin analog. F-ghrelin (green), tanycytes (red), cell nuclei (blue).

GHSR is mainly expressed in the central nervous system, where ghrelin modulates a wide variety of physiological functions through its action on different neuronal circuits. Surprisingly, studies in mice suggest that the accessibility of plasma ghrelin into the brain is very limited and restricted to specific areas that possess fenestrated capillaries. Our team has shown that plasma ghrelin is transported through the blood-cerebrospinal fluid (CSF) barrier to the CSF and from there to the brain parenchyma. We are now trying to elucidate the molecular mechanisms that control this process and its physiological relevance.