Luteinizing hormone and follicle‐stimulating hormone production in the pars tuberalis of hypophysectomized rats

Abstract

Luteinizing hormone and follicle-stimulating hormone were identified by immunocytochemistry in the same cells of the pituitary pars tuberalis, following hypophysectomy in the rat. A marked hyperplasia and hypertrophy of these cells occurred in response to hypophysectomy. These findings are discussed in light of the potential for hormone production by pars tuberalis gonadotropes following hypophysectomy performed as part of an experimental protocol, as well as that performed for palliation of human metstatic breast cancer.

Presence of Immunoreactive Luteinizing Hormone in the Rat Forebrain

“…Immunoreactive LH was also found in scattered cells of the pars tuberalis, in agreement with findings from other stud ies [7,8], The distribution of radioimmunoassayble LH in the rat brain is rather similar to that also reported for ACTH [13,16,19] and TSH [15]. It is of interest to note also that the distribution of stained neural elements is simular to that reported for ACTH [26] and prolactin [25] although much less intense than that obtained by us for ACTH [10].…”

“…It was suggested that this LH-like substance was derived from glandular cells of pars tuberalis of the pituitary which covers the surface of the me dian eminence, rather than from neural tissue. Support for this view has been provided by the demonstration of im munopositive LH in the pars tuberalis of the monkey [ I ] and rat [7,8], using immunocytochemical methods.Other than the observation of Pacold et al[21] of a bioassayable gonadotropin-like substance in the rat amygda la, no formal report has been presented of LH within the mammalian neuraxis. However, other anterior pituitarylike substances [13-16.…”

Changes in the Luteinizing Hormone Content of the Rat Pars tuheralis during the Estrus Cycle and after Lesions in the Preoptic Area

“…This finding has been confirmed by Gross [20], and further substantiated by studies in hypophysectomized rats [21,28]. In the present report we also demonstrate the presence of immunoreactive LH cells in the rat PT.…”

“…At least two types of secretory cells have been distinguished. The fine structure of one of these types is similar to that of the gonadotrophs of the pars distalis [PD; 17], Immunocytochemical studies have shown that, in the intact rat, the only cell type common to both, the PD and the PT, is that containing luteinizing hormone [LH,6], these cells become hypertrophic in short-term hypophysectomized rats [21]. Other cell types of the PD, also appear in the PT of long-term hypophysectomized rats [28], Evidence exists that the immunoreactive LH cells of the PT and those of the PD undergo the same morphological modifications after castration or estrogen treatment [20], Measurement of PD hormones in hypothalamic extracts containing the PT has showed an increase [12] or no change Received: January 16,1981 Accepted after revision: March, 1, 1982 [ 18] in LH content following castration.…”

Pituitary Hollow Fiber Units in vivo and in vitro

“…shows that the neurohemal unit of the rat median eminence remains intact after hypophysecto my. Pars tuberalis gonadotrophs, identified by immunohistochemistry, undergo hypertrophy and hyperplasis follow ing hypophysectomy [9], Although not destroyed following hypophysectomy, me dian eminence morphology is changed. There is a marked increase in growth of capillaries from the palisade zone to the internal and subependymal zone [27; Page.…”