Functional retinal input stimulates expression of astroglial elements in the suprachiasmatic nucleus of postnatal developing rat.
Astrocytes are abundant in the hypothalamic suprachiasmatic nucleus (SCN), particularly in the retinorecipient region. Using glial fibrillary acidic protein (GFAP) immunocytochemistry, we investigated the effect of light on the development of astrocytes in the SCN housing under light-dark (LD) or constant dark (DD) conditions after birth. GFAP immunoreactivity in the DD group showed lower levels than those in the LD group at P50. However, there was no difference in density of retinohypothalamic tract (RHT) terminals in the SCN between the DD and LD groups. After the adult pattern of GFAP immunoreactivity was established at P30, transferring rats to different LD conditions produced changes in GFAP immunoreactivity evident when rats were sacrificed at P50. We next examined, using a primary culture of hypothalamic astrocytes, whether neurotransmitters of RHT such as glutamate and pituitary adenylate cyclase activating polypeptide (PACAP) can stimulate GFAP expression directly. PACAP-38 increased the length and number of astrocytic processes but glutamate did not. These findings indicate that the functional aspects of RHT such as the light stimulated release of neurotransmitters is important for the development of astrocytes in rat SCN. Dynamic plasticity of astroglial elements in the SCN occurs even after GFAP shows an adult pattern.
Ikeda
Teru
T
Department of Anatomy, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kawaramachi-Hirokoji Kamikyo-ku, Kyoto 602-0841, Japan.
Iijima
Norio
N
Munekawa
Katsuhiko
K
Ishihara
Akihiko
A
Ibata
Yasuhiko
Y
Tanaka
Masaki
M
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D003624:Darkness / Q000009:adverse effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D005904:Glial Fibrillary Acidic Protein / Q000096:biosynthesis*; D008029:Lighting / Q000379:methods; D009479:Neuropeptides / Q000494:pharmacology / Q000502:physiology; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D013493:Suprachiasmatic Nucleus / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*
C495403:Adcyap1 protein, rat; D005904:Glial Fibrillary Acidic Protein; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide