Increase in somatostatin immunoreactivity in the organotypic slice culture of mouse hypothalamic suprachiasmatic nucleus

The suprachiasmatic nucleus (SCN), site of the dominant mammalian circadian clock, contains a variety of different neurons that tend to form groups within the nucleus. Somatostatin was first discovered in hypothalamic extracts and identified as a hormone that inhibited secretion of growth hormone. Subsequently, somatostatin was found to be secreted by a broad range of tissues, including pancreas, intestinal tract and regions of the central nervous system outside the hypothalamus. In vivo the localization of somatostatin immunoreactivity (SS-ir) in mouse SCN was examined before. However, detailed information about the localization and developmental distribution of SS-ir neurons in the mouse SCN slice culture is lacking. SCN derived from 3 day old mouse, were maintained in culture at the interface between air and a culture medium. SS-ir neurons are detected within the general central SCN area and the surrounding region. The density of SS-ir was clearly increased during the SCN development in organotypic slice cultures at the level of the cell bodies. The results show that not all SCN-neuropeptidergic systems decline with in vitro development, and suggest a specific age-related role for SS in the SCN. These findings may provide new morphologic evidences for explaining the functional mechanism in the SCN. [Journal of American Science 2009; 5 (7): 91-98]. (ISSN: 1545-1003).