NEUROTENSIN AND TYROSINE-HYDROXYLASE IN THE TUBEROINFUNDIBULAR SYSTEMOF THE GUINEA-PIG HYPOTHALAMUS WITH SPECIAL EMPHASIS TO LACTATION STATUS

Immunohistochemical methods allowed us to study the distribution of ne urotensin immunoreactivity (NT-IR) in the infundibular area of the gui nea pig and to obtain evidence of a clear increase of such immunoreact ivity in females during lactation. By use of the double immunolabeling method we demonstrated the presence of NT in the tuberoinfundibular d opaminergic (TIDA) neuronal system, in the nerve terminals of the medi an eminence as well as in the arcuate perikarya. In addition, NT-IR wa s detected in anterior pituitary cells especially stained in the rostr al part of the gland of lactating females. These cells were identified exclusively as gonadotrophs by use of the elution-restaining procedur e. These results suggests that NT is able to participate in the modula tion by TIDA of prolactin secretion. Moreover, NT production by gonado trophs could be responsible for other unknown pituitary actions.