Long-term effects of constant light or darkness on chicken pineal hydroxyindole-O-methyltransferase expression: biochemical and cellular aspects.
1. Chickens kept in constant light, as opposed to constant darkness, display a twofold increase in the activity of pineal hydroxyindole-O-methyltransferase (HIOMT), the last acting enzyme in the melatonin pathway. 2. Using an immunological approach, we presently show that this regulation of HIOMT activity reflects changes in the concentration of a single molecular form of the enzyme protein (a 38 kDa polypeptide). Immunohistofluorescence indicates that these concentration changes concurrently affect modified photoreceptors and pinealocyte-like cells in the chicken pineal organ. 3. Together, the present data support the hypothesis that environmental lighting might regulate the expression of the HIOMT gene.
Guerlotté
J
J
Laboratoire de Neurobiologie, URA CNRS No. 290, Poitiers, France.
Voisin
P
P
Bernard
M
M
Brisson
P
P
Falcón
J
J
Blasquez
J L
JL
Collin
J P
JP
D000121:Acetylserotonin O-Methyltransferase / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D002645:Chickens / Q000502:physiology*; D002940:Circadian Rhythm; D003624:Darkness; D004790:Enzyme Induction / Q000528:radiation effects; D008027:Light; D008550:Melatonin / Q000096:biosynthesis; D010786:Photoreceptor Cells / Q000201:enzymology / Q000528:radiation effects; D010870:Pineal Gland / Q000166:cytology / Q000201:enzymology / Q000528:radiation effects*
D000121:Acetylserotonin O-Methyltransferase; D008550:Melatonin