SCN: some morphological features

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Light →SCN: -direct via the retinohypothalamic (RHT) pathway -indirect via geniculohypothalamic (GHT) pathway

description

Light → SCN : -direct via the retinohypothalamic (RHT) pathway -indirect via geniculohypothalamic (GHT) pathway. SCN: some morphological features. Parvocellular, paired structure, ~16-20,000 neurons in rodent, miniscule in man Phenotypes: multiple potential transmitters - PowerPoint PPT Presentation

Transcript of SCN: some morphological features

Page 1: SCN: some morphological features

Light →SCN: -direct via the retinohypothalamic (RHT) pathway -indirect via geniculohypothalamic (GHT) pathway

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SCN: some morphological features

• Parvocellular, paired structure, ~16-20,000 neurons in rodent, miniscule in man

• Phenotypes: multiple potential transmitters– most express GABA (1993 proposal: SCN output is inhibitory)

– Peptides: • vasoactive intestinal peptide (VIP) in cells in ventrolateral part;

receives retinal input; forms part of the output projection • vasopressin (VP) in cells in dorsomedial part; forms part of the

output projection• somatostatin (SS) in cells whose axons remain intrinsic to SCN

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Lets consider the neural connections of SCN

A schematic outline from Ibata et al

Frontiers in Neuroendocrinology

20: 241-268, 1999

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Notes:1 -Based on

immunocytochemical grounds, SCN can be

subdivided into dorsomedial (shell) and

ventrolateral (core) segments

2 -Retinal input is to the VIPergic neurons in the

ventrolateral SCN3 -output pathways arise from both VIPergic and

vasopressinergic neurons in SCN

4 -most projections are local, to hypothalamic

sites (exceptions: LGB,

TPV)

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SCN: techniques to define input-output pathways

• Using retrograde and/or anterograde transport of suitable markers e.g. wheat germ agglutin (WGA)

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SCN: techniques to define input-output pathways

• Using retrograde and anterograde transport of suitable markers e.g. WGA

• Using viral retrograde transneuronal traceing (pseudorabies)

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Retrograde transneuronal labeling with pseudorabies virus (PRV) injected in the adrenal gland

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SCN: techniques to define input-output pathways

• Using retrograde and/or anterograde transport of suitable markers e.g. WGA

• Using viral retrograde transneuronal tracing (PRV)

• Using double label immunocytochemistry to define phenotype (peptides)

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PRV (green)

A-C: in PVN oxytocin (red)

D-E: in SCNvasopressin

(red)

F: in SCNVIP (red)

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 Anatomical and functional demonstration of a multisynaptic suprachiasmatic nucleus adrenal (cortex) pathway

European Journal of Neuroscience 11: 15351544, 1999RM Buijs, J Wortel, JJ van Heerikhuize, MGP Feenstra, GJ Ter Horst,HJ Romijn, A Kalsbeek

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