A study of the circadian rhythm and pre- and postpuberty concentrations of serum prolactin in male prairie deer mice (Peromyscus maniculatus bairdii)

Abstract

A radioimmunoassay system for measuring serum prolactin in rats was tested for its ability to measure serum prolactin concentrations in male deermice (Peromyscus maniculatus bairdii)• Preliminary assays showed that this system could be used in mice and that it had a sensitivity of 5 to 10 ng/ml. Serum prolactin was then measured at various times throughout the day to determine if a circadian rhythm existed in male mice. The results of this study indicated a single peak in serum prolactin concentrations occurred at 9*00 P.M., one hour prior to the end of the dark cycle. This study suggests that blood samples taken for prolactin analysis should be taken either at the end of the light cycle or the start of the dark cycle. It was found that serum prolactin concentrations were constant during this period. A study was done to determine pre and post puberty concentrations of serum prolactin and to determine if any correlation existed between these prolactin concentrations and the growth of the reproductive system in male mice. Serum prolactin was measured in groups of males from 10 to 90 days of age and compared with changes in body weight, testis weight, seminal vesicle weight and adrenal gland weight of males during the same age span. A significant positive correlation was found between serum prolactin and testis weight, seminal vesicle weight.and adrenal gland weight between the ages of 10 and 90 days.