a2-Adrenergic receptor subtype alterations in the
brainstem in the sudden infant death syndrome
, Sachio Takashima
, Hiroshi Tada
Department of Neonatology, Toho University School of Medicine, 6-11-1 Ohmorinishi, Ohta,
Tokyo 143-8541, Japan
Yanagawa Institution for Development Disabilities, Internal University of Health and Welfare,
Yanagawa, Fukuoka, Japan
Background: The sudden infant death syndrome (SIDS) is still the main cause of postneonatal
infant death. However, the causes and mechanisms of SIDS have never been completely elucidated.
Catecholamines, via a2-adrenergic receptor (a2-AR) interactions, are known to influence brainstem
autonomic and respiratory activity. Aims: To examine the catecholaminergic system abnormalities in
SIDS victims, we investigated the alterations of a2-AR subtypes. Subjects and methods:We
examined the developmental changes of a2-AR subtypes in the brainstem, especially in
cardiorespiratory nuclei, in 21 SIDS victims and 17 age-matched controls by means of
immunohistochemical methods. For statistical analysis, the v
-test or Fisher’s exact probability
test was performed. Results: There was a significant decrease in a2A-AR immunoreactivity in the
solitary nucleus and ventrolateral medulla (VLM) in the medulla oblongata in SIDS victims
compared with in control cases, but there were no significant differences of the a2B and a2C-AR
immunoreactivity in the brainstem between SIDS victims and controls. Conclusion: a2A-AR
immunoreactivity was selectively decreased in the solitary nucleus and VLM in the medulla
oblongata in SIDS victims, so there was no possibility that it was secondary to chronic hypoxia or
repeated ischemia. It may be related to some impairment of the cardiorespiratory neuronal system.
Therefore, SIDS victims may be vulnerable to asphyxia, hypoxia, and/or hypercapnia, and fail to
exhibit brainstem responses.
D 2003 Published by Elsevier Ireland Ltd.
Keywords: Sudden infant death syndrome; a2-Adrenergic receptor; Brainstem
0378-3782/$ - see front matter D 2003 Published by Elsevier Ireland Ltd.
* Corresponding author. Tel.: +81-3-3762-4151; fax: +81-3-3762-9376.
E-mail address: hy
firstname.lastname@example.org (Y. Ozawa).
Early Human Development 75 Suppl. (2003) S129 – S138