Piggins, Hugh D. and Samuels, Rayna E. and Coogan, Andrew and Cutler, David J. (2001) Distribution of substance P and neurokinin-1 receptor immunoreactivity in the suprachiasmatic nuclei and intergeniculate leaflet of hamster, mouse, and rat. The Journal of Comparative Neurology, 438 (1). pp. 50-65. ISSN 0021-9967

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Abstract

he circadian pacemaker in the hypothalamic suprachiasmatic nuclei (SCN) receives photic information directly via the retinohypothalamic tract (RHT) and indirectly from retinally innervated cells in the thalamic intergeniculate leaflet (IGL) that project to the SCN. Using standard immunohistochemical methods, we examined the presence and distribution of substance P (SP) and the neurokinin-1 receptor (NK-1) in the SCN and IGL of rat and determined whether the patterns of immunostaining generalized to the SCN and IGL of Syrian hamster, Siberian hamster, and mouse. Terminals immunoreactive for SP were sparse within the SCN of Siberian and Syrian hamsters and mouse but were intense in the ventral, retinally innervated portion of the rat SCN. Immunostaining for the NK-1 receptor was mainly absent from the SCN of hamster and mouse. In contrast, a plexus of NK-1-ir cells and processes that was in close proximity to SP-ir terminals was found in the ventral SCN of the rat. Substance P-ir terminals were observed in the IGL of all four species, as were NK-1-ir cells and fibres. Double-labelled IGL sections of hamster or rat revealed SP-ir terminals in close apposition to NK-1-immunostained cells and/or fibres. These data indicate that SP could be a neurotransmitter of the RHT in rat, but not in hamster or in mouse, and they highlight potential species differences in the role of SP within the SCN circadian pacemaker. Such species differences do not appear to exist at the level of the IGL, where SP-ir and NK-1-ir were similar in all species studied.

Item Type:	Article
Keywords:	circadian rhythm; immunohistochemistry; rodent; hypothalamus; lateral geniculate nucleus; retinohypothalamic tract;
Academic Unit:	Assisting Living & Learning,ALL institute Faculty of Science and Engineering > Psychology Faculty of Science and Engineering > Research Institutes > Human Health Institute
Item ID:	16469
Identification Number:	https://doi.org/10.1002/cne.1301
Depositing User:	Dr. Andrew Coogan
Date Deposited:	30 Aug 2022 16:06
Journal or Publication Title:	The Journal of Comparative Neurology
Publisher:	Wiley
Refereed:	Yes
URI:	Publisher
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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