Ns. Lipman et al., PROLACTIN-SECRETING PITUITARY-ADENOMAS WITH MAMMARY DYSPLASIA IN NEW-ZEALAND WHITE-RABBITS, Laboratory animal science, 44(2), 1994, pp. 114-120
Nine aged (mean age = 3.2 years) nulliparous New Zealand white rabbit
does were found to have markedly enlarged teats. The teats were freque
ntly engorged with fluid but were not hot and did not cause signs of p
ain. The number of affected teats per animal ranged from 1 to 8 (mean
= 4). The teats and associated glandular tissue were typically discolo
red grey, blue, or greenish black (n = 6). Prolactin concentrations we
re evaluated by radioimmunoassay. Serum prolactin concentrations range
d from 22.4 ng/ml to 2.21 mu g/ml (mean = 397.3 ng/ml), which was 10 t
o 1000-fold greater than normal values in nonpregnant rabbits. Convent
ional radiography of the skull of six rabbits did not reveal pituitary
enlargement. Necropsy revealed an enlarged pituitary gland and sella
turcica in six of nine does. The diaphragma sellae had ruptured in two
rabbits. All nine rabbits had pituitary acidophil adenomas. The neopl
astic portions of the pituitaries were diffusely immunoreactive when s
tained immunohistochemically for prolactin. In contrast, only small cl
usters of five to seven cells stained positively in normal pituitaries
selected as controls. Histologic examination of the mammary glands re
vealed numerous large, dilated cystic spaces containing proteinaceous
fluid. Many cysts had numerous papillary epithelial infoldings. The cy
stic dilations extended into and included the teat canal producing the
gross appearance. Prolactin-secreting acidophil adenomas have not bee
n previously reported in the rabbit, and the association with mammary
dysplasia is unique.