Characterization of orexin A immunoreactivity in the rat area postrema.

Full Abstract

The distribution of orexin A immunoreactivity and the synaptic relationships of orexin A-positive neurons in the rat area postrema were studied using both light and electron microscopy techniques. At the light microscope level, numerous orexin A-like immunoreactive fibers were found within the area postrema. Using electron microscopy, immunoreactivity within fibers was confined primarily to the axon terminals, most of which contained dense-cored vesicles. Both axo-somatic and axo-dendritic synapses made by orexin A-like immunoreactive axon terminals were found, with these synapses being both symmetric and asymmetric in form. Orexin A-like immunoreactive axon terminals could be found presynaptic to two different immunonegative profiles including the perikarya and dendrites. Occasionally, some orexin A-like immunoreactive profiles, most likely to be dendrites, could be seen receiving synaptic inputs from immunonegative or immunopositive axon terminals. The present results suggest that the physiological function of orexin A in the area postrema depends on synaptic relationships with other immunopositive and immunonegative neurons, with the action of orexin A mediated via a self-modulation feedback mechanism.

Author information

Author/s: Guan, Jian-Lian (JL); Wang, Qing-Ping (QP); Kageyama, Haruaki (H); Kita, Tetsuro (T); Takenoya, Fumiko (F); Hori, Tomoko (T); Shioda, Seiji (S);

Affiliation: Department of Anatomy, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan.

Journal and publication information

Publication Type: Journal Article

Journal: Regulatory peptides (Regul Pept), published in Netherlands. (Language: eng)

Reference: 2005-Jul; vol 129 (issue 1-3) : pp 17-23

Dates: Created 2005/06/01; Completed 2005/09/14; Revised 2006/11/15;

PMID: 15927693, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: )

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