1. 1. Pineal levels of tryptophan, 5-hydroxytryptophan, serotonin, N-acetylserotonin, melatonin, 5-hydroxyindoleacetic acid and the enzyme activities of N-acetyltransferase and hydroxyindole-O-methyltransferase were determined in male albino rats and Syrian hamsters that were injected with insulin twice daily for three days, or injected with streptozotocin to induce diabetes. 2. 2. Neither insulin injections nor streptozotocin diabetes had any effect on pineal melatonin production in rats. 3. 3. In hamsters, diabetes reduced the nocturnal peak of pineal melatonin content by approximately one half, while insulin injections had no effect on pineal melatonin levels; however, insulin injections did cause a slight increase in pineal N-acetyltransferase activity. 4. 4. These findings indicate that the pineal gland of the hamster may be more sensitive to alterations in plasma insulin levels than the same organ in rats.
|Original language||English (US)|
|Number of pages||5|
|Journal||Comparative Biochemistry and Physiology -- Part A: Physiology|
|State||Published - 1986|
ASJC Scopus subject areas