Pituitary Prolactin Cell Hyperplasia

Kovács, Kálmán; Ilse, G.; Ryan, Nancy; McComb, Donna J.; Horváth, Éva; Chen, H.J.; Walfish, P. G.

doi:10.1159/000179108

Cited by 26 publications

(5 citation statements)

References 9 publications

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“…A later study found evidence of prolactin cell hyperplasia (10). A study of male and female Wistar rats revealed a high incidence of spontaneous pituitary tumors and hyperplastic nodules, most of which contained prolactin, and only a few tumors contained GH, TSH, and ACTH (1).…”

Section: Resultsmentioning

confidence: 99%

An Immunocytochemical Study of Pituitary Adenomas and Focal Hyperplasia in Old Sprague-Dawley and Fischer 344 Rats

et al. 1988

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Spontaneous pituitary tumors occumng in groups of 100 Sprague-Dawley (SD) and 100 Fischer 344 (F344) rats of each sex on a 2-year aging study were characterized by immunocytochemistry. The SD strain had a total of 75 tumors with 10% in males and 65% in females. Tumors immunoreactive for prolactin (PRL) alone were the most common tumor (64%) with the immunonegative tumor being the second most common (17.3%). F344 rats had a total of 62 tumors with 26% in males and 36% in females. The majority of the tumors were reactive for prolactin alone (56.5%) and tumors reactive for both growth hormone (GH) and PRL were the second most common (21%). Most tumors were immunoreactive for only 1 hormone; however, both strains had tumors that expressed multiple hormones in unusual combinations.

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Section: Resultsmentioning

confidence: 99%

An Immunocytochemical Study of Pituitary Adenomas and Focal Hyperplasia in Old Sprague-Dawley and Fischer 344 Rats

et al. 1988

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“…Since an ingrowth of arteries from the dura would bypass the hypothalamus and the classic hypothalamo-hypophyseal circulation, mammotrophs would escape dopamine inhibition with a resultant hypertrophy and hyperplasia. Mammotroph hypertrophy and hyperplasia are known to precede the formation of prolactinomas (Kovacs et al, 1980). The vasculature of the pars distalis of S-D rats (Simonsen Laboratories) did not include arteries or evidence of vascular reorganization comparable to that in F344 rats.…”

Section: Discuss 1 0 Nmentioning

confidence: 99%

“…Based on macroscopic observation, they concluded that arteriogenesis, derived from the dural vessels adjacent to the pars distalis, had occurred in the estrogen-treated Fischer 344 rats, but to a lesser degree in Sprague-Dawley rats. Arteries entering the pars distalis in this manner would contain blood free of hypothalamic inhibitory neurohormones, the absence of which could stimulate the mammotroph hypertrophy and hyperplasia that precede prolactinoma formation (Kovacs et al, 1980). Thus, estrogen may exert its initial influence on prolactinoma formation through an interaction with the vasculature.…”

Section: Introductionmentioning

confidence: 99%

Estrogen‐induced tumors: Changes in the vasculature in two strains of rat

et al. 1987

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The influence of estrogen on the vasculature of the pars distalis has been studied in two strains of rat that differ in estrogen responsiveness. (Fischer 344 rats are highly estrogen-responsive in comparison to Sprague-Dawley rats.) Ovariectomized adults were implanted with silastic capsules containing 17 beta-estradiol benzoate. Control and experimental animals were sacrificed 10 and 20 days after implantation of the silastic capsules. Pituitary weights and plasma prolactin were elevated dramatically in estrogen-treated Fischer rats in comparison to more moderate increases in Sprague-Dawley rats. Although both strains exhibited the hypertrophy of mammotrophs expected after estrogen stimulation, the vasculature in Fischer rats were dramatically altered from normal. The pars distalis of the 20-day, estrogen-treated Fischer rats contained well-formed arteries. In addition, capillaries frequently were disrupted, contributing to the formation of hemorrhagic lakes unlined by an endothelium. Even in intact capillaries, basal laminae delimiting the pericapillary spaces often were disrupted or absent. Perivascular connective tissue cells were prominent within the perivascular spaces and often contained numerous, large lysosomal dense bodies as well as clusters of small dumbbell-shaped bodies. These granule clusters also were apparent adjacent to the perivascular space within parenchymal cells, most frequently within follicular cells. The vasculature of Sprague-Dawley rats maintained a more normal appearance after estrogen treatment, although perivascular connective tissue cells did appear activated and basal laminae delimiting the pericapillary spaces were disrupted occasionally. However, no capillaries were disrupted, nor were any hemorrhagic lakes evident, and no arteries were present.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…[10][11][12] The escape from hypothalamic inhibitory control leads to lactotroph hyperplasia of the pituitary gland and a high rate of prolactin-producing pituitary adenomas in geriatric rats. 9,13 On light microscopic examination, most prolactin-producing pituitary adenomas of rats contain large spaces filled with RBCs. Large tumors have areas of focal necrosis and macrophage infiltrates.…”

Section: Discussionmentioning

confidence: 99%