The response of the pineal melatonin biosynthesis to the selective MAO-A inhibitor, clorgyline, in young and middle-aged rats.
1. Clorgyline increased pineal melatonin and N-acetylserotonin (NAS) and decreased 5-hydroxyindoleacetic acid (5-HIAA) content in 3 and 12 months of age male Sprague-Dawley rats kept under 12:12 h light: dark schedule. Exposure to light for 24 h before clorgyline administration resulted in additional elevation of NAS and melatonin. NAS and melatonin levels after clorgyline injections were significantly higher while 5-HIAA levels were significantly lower in young than in middle-aged rats. 2. The 5-HIAA/5-HT ratio (index of monoamine oxidase activity) was higher in middle-aged than in young rats suggesting the lesser degree of clorgyline-induced inhibition of MAO-A in old than in young rats. 3. It is suggested that melatonin response to a single dose of the selective MAO-A inhibitor might be used for the assessment of the aging changes of the rat (and human) pineals.
Oxenkrug
G F
GF
Pineal Research Laboratory, VA Medical Center, Providence, R.I.
McIntyre
I M
IM
Requintina
P J
PJ
Duffy
J D
JD
D000375:Aging / Q000378:metabolism*; D000818:Animals; D003010:Clorgyline / Q000494:pharmacology*; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008027:Light; D008297:Male; D008550:Melatonin / Q000096:biosynthesis*; D010870:Pineal Gland / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000031:analogs & derivatives / Q000378:metabolism
D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D008550:Melatonin; D003010:Clorgyline; C006389:N-acetylserotonin