Masters Theses


John E. Fritz

Date of Award


Degree Type


Degree Name

Master of Science


Animal Science

Major Professor

H. V. Shirley


The pineal of certain birds and mammals are known to contain bio-logically active amines which, with their enzymes, show circadian varia-tions. In the rat. Quay et al.8 have shown diurnal cycles in levels of pineal melatonin and 5-hydroxytryptamine (serotonin) (Quay et al.9). Additionally, the activities of two pineal enzymes, hydroxy-indole-0- 21 methyltransferase (Axelrod et al.21) and N-acetyltransferase (Klein et al.20 have been described. Birds also possess circadian rhythms for those parameters described above. This investigation is a comparative study of the response of Gallus domesticus to changes in environmental lighting conditions as well as to the effects of pinealectomy on chosen internal body parameters. Various lighting and operative conditions were used, and the follow-ing materials were quantitatively analyzed: (1) blood glucose levels, (2) serum calcium, (3) liver glycogen, (4) N-acetyltransferase, (5) 5-hydroxytryptamine (serotonin), (6) hydroxy-indole-0-methyltransferase, and (7) 5-methoxytryptamine (melatonin). The analysis included determining whether the animal possessed a cir-cadian rhythm under control conditions (12 hours light - 12 hours dark) and if the rhythms might be upset, or varied, by changing the external light patterns. Results from these experiments, although they are in somewhat dis-agreement with those of other investigators, strongly support a conclu-sion that the pineal gland acts as an extraretinal photoreceptor. The hydroxy-amines and those enzymes responsible for their formation afforded prime examples of circadian rhythms, and the control of those rhythms by an external stimulus (light). The basis for the studies was to determine whether or not the response of animals to light is monitored by the pineal and what the response dictates to the various body parameters which have previously been mentioned. The results of our studies on the above mentioned are described fully in the following chapters.

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