Immunohistochemical examination of the paraadenomatous "normal" pituitary. An evaluation of prolactin cell hyperplasia.

Prolactin cell hyperplasia has been described to occur in the paraadenomatous normal pituitary gland surrounding prolactinomas. However, compression of the glandular lobules and secretory cells alters profoundly the histological configuration of this tissue. No changes resembling those that occur during pregnancy are found. Immunohistochemical staining and counting of prolactin-(PRL-)secreting and growth hormone-(GH-)secreting cells in the normal, paraadenomatous pituitary gland obtained during extirpation of 24 prolactinomas and 5 adenomas causing acromegaly demonstrated that GH-secreting cells predominated in all biopsies obtained from acromegalic patients. PRL-secreting cells were more frequent than GH-secreting cells in 14 of 24 biopsies of the normal tissue surrounding prolactinomas. A particular predominance of PRL-secreting cells was found in patients with postoperative residual hyperprolactinemia. Direct comparison of adjacent sections demonstrates three cell types: One reacts with both antibodies and the other two react only with one or the other. We suggest that these groups are not stable but that cells belonging to one group can be transformed into cells belonging to the two other groups. Such a process, induced by extrahypophyseal factors, may explain the shift of relative cell frequency observed in the normal pituitary gland surrounding prolactinomas.

Bromocriptine reduces the size of cells in prolactin-secreting pituitary adenomas.

The morphometric analysis of the size of adenomatous prolactin cells shows that bromocriptine-induced cell shrinkage halts if treatment with the drug is discontinued for more than 2 days. Different cell components (nucleus, cytoplasm, nucleolus) do not react to treatment to the same extent.

In vitro fermentation of feces from normal and chronically diarrheal horses.

Feces from 13 healthy horses and 8 horses with chronic diarrhea were subjected to an in vetro fermentation procedure that had been developed for rumen fluid. Fermentations were conducted over 6 hours in a closed system, with and without an essential amino acid (EAA) mixture being added to the basic starch-buffer medium. The addition of EAA caused no significant difference in results of fermentation of feces from healthy horses. For diarrheic animals, there was a significant (P less than 0.01) increase in gas and total volatile fatty acids production whether EAA were present or not, and alpha-amino nitrogen was utilized in significantly (P less than 0.01) greater amounts only if EAA was present. Fermentations were repeated on feces from five of the eight diarrheal horses after they had been treated with oral iodochlorhydroxyquin for 1 week, and had shown desirable clinical response. A significant difference was not shown between pre- and posttreatment fermentations, except for decreased butyrate production. The results are consistent with the hypothesis that chronic equine diarrhea is primarily a colonic disease and indicates that colonic maldigestion may, in part, be responsible for excess fecal water.