Motilin-like immunoreactivity in the canine pituitary and pineal glands--a histochemical study

Abstract

Motilin-like immunoreactivity in the canine pituitary and pineal glands shown by radioimmunoassay was re-investigated by histochemistry using anti-porcine motilin sera. Immunostaining of duodenal Mo cells was examined as a control. Tissues were fixed in Bouin's fluid and embedded in paraffin. Sternberger's peroxidase anti-peroxidase method was employed for histochemical reaction. Three lots of anti-motilin sera raised in rabbits ( R1104 , R1105 , R1106 ) and one lot of anti-motilin serum raised in a guinea pig ( GP2803 ) were used. An absorption test of the immunohistochemical reaction was performed using motilin (Mo 1-22), N-terminal fragment (Mo 1-17), or C-terminal fragment (Mo 7-22). The results obtained were summarized as follows: In the pituitary gland, endocrine cells showing motilin-like immunoreactivity were localized in the pars distalis and pars intermedia. In the pineal gland, pinealocytes showed no motilin-like immunoreactivity. Pituitary endocrine cells were strongly stained with two lots of anti-motilin sera ( R1104 , R1105 ). No distinct reaction was demonstrated with two other anti-motilin sera ( R1106 , G2803 ). The minimum concentration of antigens required for absorption of the immunohistochemical reaction was determined by their doubling-dilution. When R1105 anti-serum (1:1000) was pre-incubated with Mo 1-22, immunostaining of duodenal Mo cells re-appeared at a concentration of 0.1 X 2(-8) g/l, whereas pituitary endocrine cells remained unstained at a concentration of 0.1 X 2(-10) g/l. Using Mo 7-22, immunostaining of pituitary endocrine cells was absorbed up to a concentration of 0.1 X 2(-14) g/l, whereas duodenal Mo cells were positively stained at a concentration of 0.1 X 10(-6) g/l.(ABSTRACT TRUNCATED AT 250 WORDS)