Optic nerve stimulation-induced increase of release of 3H-glutamate and 3H-aspartate but not 3H-GABA from the suprachiasmatic nucleus in slices of rat hypothalamus.
This study investigates the possibility of glutamate and/or aspartate as an excitatory transmitter in the retinohypothalamic fibers' terminal within the anterior hypothalamus, including the suprachiasmatic nucleus (SCN). We studied the release of 3H-Glu and 3H-Asp from the SCN of rat hypothalamic slices produced by optic nerve stimulation. Stimulation of the optic nerve released 3H-Glu, 3H-Asp but not 3H-GABA, while stimulation of the SCN released all three. These releases were suppressed in both Ca2+ free Krebs and tetrodotoxin (TTX) 1 microM containing Krebs. The present result with previous electrophysiological observations strongly suggest that glutamate and/or aspartate are included in this retinohypothalamic termination, while GABA is included in intrinsic and/or extrinsic neurons of the SCN, excluding the terminal of the retinohypothalamic fibers.
Liou
S Y
SY
Shibata
S
S
Iwasaki
K
K
Ueki
S
S
D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism*; D004558:Electric Stimulation; D004594:Electrophysiology; D005971:Glutamates / Q000378:metabolism*; D018698:Glutamic Acid; D066298:In Vitro Techniques; D018377:Neurotransmitter Agents / Q000378:metabolism; D009900:Optic Nerve / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013493:Suprachiasmatic Nucleus / Q000378:metabolism*; D014795:Visual Pathways / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D005971:Glutamates; D018377:Neurotransmitter Agents; D001224:Aspartic Acid; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid