DIFFERENCES IN THE DISTRIBUTION OF PROTEINS ASSOCIATED WITH ω-CONOTOXIN RECEPTORS IN RAT PITUITARY CELLS

Two monoclonal antibodies, SPM-1 and SPM-2, raised against brain synaptic membrane specifically recognized two different ω-conotoxin receptor-associated proteins with molecular masses of 36 kDa and 28 kDa, respectively. In the anterior lobe of the rat pituitary, all secretory cells were immunostained with SPM-2, but not with SPM-1, although folliculo-stellate cells were stained with both SPM-1 and SPM-2. Castration or stimulation with hypothalamic hormones caused an increase in the intensity of the SPM-2 staining in hormone-secretory cells. In the intermediate lobe, all secretory cells showed a strong 28-kDa-protein immunoreactivity. In the posterior lobe, the immunoreactivity to both SPM-1 and SPM-2 was recognized in nerve endings