Microglia in the pineal gland of the neonatal rat: characterization and effects on pinealocyte neurite length and serotonin content.
Microglia in the pineal gland of 1-day-old Sprague-Dawley rats were examined by OX-42 immunocytochemistry and DiI-acetylated-LDL uptake in pineal cell suspension and were found to comprise 3-5% of the total cells in the pineal gland of the neonates. In order to investigate the effects of microglia on pinealocyte structure and function, microglia-depleted and microglia-enriched pineal cell cultures were generated from 1-day-old neonate by fluorescence activated cell sorting (FACS). After 7 days of culture, tissues were processed for either immunocytochemistry for pinealocyte S-antigen and serotonin or high performance liquid chromatography to measure serotonin. Morphometric analysis of immunoreacted cells revealed that pinealocyte neurite length was enhanced in microglia-depleted cultures and was inhibited in a microglia-enriched environment (ANOVA, P < 0.001). Serotonin content of pineal cultures decreased in microglia-depleted cultures and was elevated in microglia-enriched cultures (ANOVA, P < 0.001) without any significant change in pinealocyte numbers. These findings are consistent with a working hypothesis that microglia function to mediate neuroendocrine-immune interactions of the gland.
Tsai
S Y
SY
Department of Cell Biology, Neurobiology and Anatomy, Stritch School of Medicine, Loyola University of Chicago, Maywood, Illinois 60153, USA.
McNulty
J A
JA
D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D005260:Female; D008297:Male; D017628:Microglia / Q000166:cytology* / Q000378:metabolism; D016501:Neurites; D010870:Pineal Gland / Q000166:cytology* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*
D012701:Serotonin