The effect of stress upon the determination of serum prolactin by radioimmunoassay.

Abstract

SummarySerum prolactin concentrations were determined by radioimmunoassay during estrus cycles in 15 dairy heifers bled by repeated jugular punctures or from a long, indwelling jugular catheter. The method of bleeding was found to influence the serum prolactin concentration and was attributed to nonspecific stress. Further confirmation for the stress effect was provided by a controlled study in other heifers, submitted to specific forms of acute and chronic stress stimuli. In cattle, studies of blood prolactin concentrations under various physiological conditions may be performed only when environmental conditions are carefully controlled.