Endocrine Abstracts

The hypothalamic paraventricular nucleus (PVN) is a major regulatory centre of energy homeostasis by possessing the unique capability of simultaneously controlling endocrine axes, water balance and autonomic functions. It receives neuronal information form orexigenic and anorexigenic cell groups of the basal hypothalamus that monitor peripheral metabolic signals (leptin, insulin, ghrelin, glucose, glucocorticoids) and also from brainstem centers relaying sensory information from visceral organs. In the regulation of energy homeostasis, the hypophysiotrophic corticotropin-releasing hormone (CRH) and thyrotropin-releasing hormone (TRH) neuronal systems play a key role and both neuron populations are wired to neuronal circuits of the basal hypothalamus and the brainstem. The lecture provides information about the structural organization, functional domains and major neuronal connections of the PVN, introduces the novel glutamatergic phenotype of hypophysiotrophic CRH and TRH systems, elucidates the diverse chemical nature of their synaptic afferents and describes the structural correlates of retrograde endocannabinoid signalling acting upon inhibitory and excitatory presynaptic terminals in the nucleus. The presentation also reveals distinct hypothalamic and extrahypothalamic sources of neuronal afferents carrying orexigenic (NPY) and anorexigenic (CART) peptides to TRH and CRH neurons and demonstrates the impact of the released neuropeptides on the postsynaptic targets. In addition to rodent data, the interrelationship of NPY and α-MSH neuronal systems and the features of their projections to CRH and TRH neurons will be presented in post-mortem human hypothalamic samples.

Supported by grants from the National Science Foundation of Hungary (OTKA T046492, T046574), NKFP 1A/002/2004 and the Sixth EU Research Framework Programme (LSHM-CT-2003-503041).