Plasma from pituitary stalk blood or plasma from femoral artery blood from one group of rats (donors) was infused (at the rate of 2 μl/min for 30 min) into a hypophysial portal vessel of other rats (recipients). Infusion of stalk plasma from donor animals, which had been given 1.25 μg dopamine hydrochloride via the third ventricle, caused a marked increase in the release of LH and FSH in the recipients but a decrease in the release of prolactin. Infusion of stalk plasma from donors not given dopamine had a slight but statistically insignificant effect on the release of LH, FSH, or prolactin in the recipient animals. Infusion of arterial plasma from both types of donors had no effect on the release of these three hormones. These results are considered to indicate that LRF, FRF, and PIF activities in stalk blood are increased following the administration of dopamine via the third ventricle.
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