A comparison of the release of endogenous dopamine from the neural and the intermediate lobe of the rat hypophysis after electrical stimulation of the stalk.

Dopamine (DA) was released from the isolated neural lobe of the pituitary gland by electrical stimulation of the pituitary stalk. This observation completes the evidence for DA to be classified as a neurotransmitter substance in the neural lobe in the rat hypophysis. From the experiments on the isolated neural lobe and simultaneous experiments on the combined neuro-intermediate lobe it could be calculated that the DA release from the intermediate lobe was about three times larger than that from the neural lobe. Electrical stimulation of the pituitary stalk in the presence of pargyline and TEA led to an increase in DA synthesis in the neural lobe. This effect did not occur in the intermediate lobe.