This research will examine two aspects of reproductive control by the environmental day-night cycle. First, Stetson plans to examine the mechanisms by which two species of hamsters measure day length. The primary focus will be the functional relationship between the environmental light cycle, the animal's brain and its pineal gland. This gland has been shown by many investigators, ourselves included, to translate neural signals designating day length into hormonal (melatonin) output. The primary interest is an understanding of the means by which melatonin output is read by the hamster as a long day (stimulating reproduction) or a short day (inhibiting reproduction). Second, Stetson plans to continue his examination of the means by which pregnant hamsters transmit daylength information to their fetuses. This information is used by the young, after birth, to regulate their response to daylengths of intermediate duration. Again, the maternal pineal gland and its hormone melatonin is involved in this process. He plans to examine possible mechanisms that coordinate and regulated this information transfer process.
