Beta-adrenergic stimulation prior to darkness advances the nocturnal increase of Syrian hamster pineal melatonin synthesis.
Pineal glands of male Syrian hamsters stimulated in vivo with isoproterenol (ISO) for 4 h before the onset of darkness showed a 4-h advance in the timing of the nighttime increases in both N-acetyltransferase activity and melatonin levels. When ISO (1 mg/kg) was administered every 2 h to animals kept in light during the night, a significant increase in melatonin synthesis was observed after 4-6 h. The results suggest that the Syrian hamster pineal gland can respond in vivo to continuous beta-adrenergic stimulation, but a lag period of 4-6 h is required before there is an increase in melatonin synthesis.
Gonzalez-Brito
A
A
Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio 78284.
Reiter
R J
RJ
Santana
C
C
Menendez-Pelaez
A
A
Guerrero
J M
JM
D000818:Animals; D002940:Circadian Rhythm / Q000187:drug effects*; D006224:Cricetinae / Q000378:metabolism* / Q000502:physiology; D003624:Darkness; D007545:Isoproterenol / Q000494:pharmacology*; D008550:Melatonin / Q000378:metabolism* / Q000502:physiology; D010870:Pineal Gland / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism*
D011943:Receptors, Adrenergic, beta; D008550:Melatonin; D007545:Isoproterenol