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 58,342 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The rostral pars distalis of the anterior pituitary gland of the marine alewife, Alosa pseudoharengus, during its annual spawning run to fresh water was examined histologically. The rostral pars distalis is composed of many interconnecting follicles of various sizes. Contrary to earlier reports, the follicular epithelium contains not only prolactin (PRL) cells but corticotropic (ACTH) cell and thyrotropic (TSH) cells (in addition to two nonendocrine cell types). Basally all three endocrine cell types make direct contact with the basement membrane which separates the follicles from the neurohypophysial processes. Apically, however, only the prolactin cells, the largest of the three, protrude into the follicular lumen by means of the small ciliated apical protruberance. All other cellular elements are sealed from the follicular lumen by a layer of covering cells which have properties of transitional epithelial cells. In the follicular epithelium, the slender TSH cells are intercalated between the large conspicuous prolactin cells. The ACTH cells, the smallest of the three endocrine cells, lie in deep invaginations in the basal regions of the individual PRL cells in such a way that on cursory examination they can be mistaken for the nuclei of the latter. Only a small portion of the cellular surface of the ACTH cell escapes the enveloping prolactin cell to make contact with the basement membrane of the follicle. In teleosts, prolactin, ACTH, and TSH have all been implicated in the regulation of hydromineral metabolism and reproductive development. The intimate spatial relation between the three endocrine cells in the alewife rostral pars distalis thus raises the possibility of some functional interactions at the adenohypophysial level, perhaps as an adaptation of this anadromous teleost whose reproductive development and behavior is associated with large changes in ambient salinity. The functional significance of the follicular lumen is discussed together with possible sensory functions of the PRL cells.
Anat Rec 1981 Mar
PMID:Cellular composition of the rostral pars distalis of the anterior pituitary gland of the alewife, Alosa pseudoharengus, during the spawning run. 626 81

In vivo experiments showed that anti-bovine luteinizing hormone rabbit serum (a-LH) reversed the abortifacient effect of Bromergocryptine (BEC) on day 6 of pregnancy in 13 of 19 rats when injected 5-15 h after the initial BEC administration. Radioreceptor assay studies revealed that BEC treatment entailed an 85% drop of ovarian LH-receptor (LH-rec) concentration and a drastic decrease in progesterone serum levels. a-LH restored both the ovarian LH-rec content and progesterone serum levels in those rats that were found to have macroscopically intact implantations. A time course study of LH serum levels after BEC treatment showed a trend for BEC to stimulate LH secretion with a maximum 12-18 h after the initial BEC injection. These experiments indicate that (i) BEC terminates early rat pregnancy primarily by inducing a process of desensitization of ovarian LH-rec by blocking prolactin (PRL) secretion and possibly also by additionally stimulating LH secretion, which in the absence of endogenous PRL causes HL-rec and serum progesterone levels to drop; (ii) a-LH administration without simultaneous PRL substitution may rescue LH-rec of BEC treated rats from being desensitized as well as prevent fetuses from being resorbed. It is suggested that the contribution of PRL in the luteotropic complex is permissive for the luteotropic action of LH and/or for keeping the corpus luteum in a functional state rather than being luteotropic by itself.
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PMID:Antiserum to LH reverses the abortifacient effect of Bromergocryptine treatment in early rat pregnancy. 629 83

Clonal pituitary cells (2B8) derived from embryonic Rathke's pouch epithelium of Wistar-Imamichi rats established by Ishikawa et al. (1977) were used in this study. Late-passage 2B8 cells were found to contain small secretory granules which contained immunoreactive prolactin as demonstrated by electron microscopic immunocytochemistry. When 2B8 cells were incubated in the presence of various agents that are known to stimulate or inhibit prolactin secretion, the volume density of the secretory granules in the cytoplasm was shown to be altered.
Anat Rec 1983 May
PMID:Identification and responsiveness of prolactin-containing secretory granules in clonal rat mammotrophs. 634 24

Thyrotropin-releasing hormone (TRH) stimulates prolactin production in cultured GH3 rat anterior pituitary tumor cells. For correlation of cell-by-cell prolactin distribution and intracellular hormone concentration, GH3 cells were grown to plateau-phase density on glass coverslips in plastic dishes. Acetone-fixed, cell-bearing coverslips were stained for prolactin by an immunoglobulin-peroxidase bridge technique (Mason et al., '69); cells on the plastic dishes were assayed for prolactin (microcomplement fixation immunoassay, Tashjian, '73) and protein content. Intracellular prolactin, unaffected quantitatively by acetone fixation and choice of substratum, was localized immunocytochemically by a granular brown precipitate, abolished if anti-prolactin serum was preabsorbed with rat prolactin or omitted from the protocol. Intracellular prolactin was maximized with colchicine (5.0 X 10(-6) M; final 3 hr of incubation) in control and TRH-treated (10 ng/ml; 48 hr) GH3 cell cultures. A total of 8,500 cells were classified by light microscopy as unstained, heavily (H) or moderately (M) stained for prolactin. In controls, 35% of cells were prolactin-positive: 5% H and 29% M. After TRH, 45% were positive: 7% H and 38% M. Although prolactin-positive cells were unevenly distributed, comprising 25% to 46% of cells in individual microscopic fields in controls, TRH increased the proportion of M cells in all areas. TRH treatment raised prolactin levels to 450% of control, but mathematical analysis attributed less than 30% of the increase to new prolactin-positive cells. We conclude that TRH acts on GH3 cultures principally by raising the mean hormone content of individual positive cells rather than by increasing the proportion of cells committed to prolactin production.
Anat Rec 1980 Jun
PMID:Immunocytochemical analysis of prolactin production by monolayer cultures of GH3 rat anterior pituitary tumor cells: I. Long-term effects of stimulation with thyrotropin-releasing hormone (TRH). 677 30

The preceeding report (Hoyt and Tashjian, '80) correlates immunocytochemical localizations and mean prolactin concentrations in GH3 monolayers maximally stimulated with TRH; the present does so over the duration of TRH treatment. Low density seeding produced numerous discrete GH3 cell colonies. Cultures were harvested 1/2, 4, 12, 24, 72, and 144 hr after administration of TRH (50 ng/ml) or saline (control). All cells (42,658 total) in at least 10 microscopic fields/monolayer, 1 cell colony/field, were classed as unstained, heavily (H), moderately (M), or weakly (W) stained for prolactin. In controls, colonies contained 51-91 prolactin-positive cells/100 of population. Colonies with few positive cells had many more W than M cells, and the reverse was true in those with many positive cells. In all colonies, the effect of TRH was biphasic, Initial (0-4 hr) release of prolactin was overlapped, beginning at 3-4 hr, by a progressive increase of intracellular hormone. After 144 hr, the prolactin content of treated cultures had increased to 190% of control, and prolactin-positive cells were more numerous (114% of control). These increases were lower than those reported in the preceeding paper after 48 hr of TRH treatment, when intracellular prolactin equalled 450% of control and positive cells equalled 129% of control. These inconsistencies reflect differences in the control level of prolactin production rather than in the absolute effects of TRH, which were virtually identical in the successive experiments. We conclude that: 1) TRH acts to alter hormone production in cells already making prolactin; 2) TRH increases somewhat the number of prolactin-containing cells; 3) the relative contribution of such "new" cells to increased hormone output depends on the basal level of prolactin production, which differs among individual GH3 cell colonies and varies over time in culture. This diversity does not diminish the usefulness of GH3 cells as biochemical models of hormone biosynthesis. It does hinder their valid morphological evaluation, which apparently must be controlled as carefully as biochemical experiments and should include immunocytochemical localizations, at least for the hormone at issue.
Anat Rec 1980 Jun
PMID:Immunocytochemical analysis of prolactin production by monolayer cultures of GH3 rat anterior pituitary tumor cells: II. Variation in prolactin content of individual cell colonies, and dynamics of stimulation with thyrotropin-releasing hormone (TRH). 677 31

A condition of protein-calorie malnutrition was precipitated in young Sprague-Dawley male rats at 20 days of age using an 8% low protein diet (LPD). At five-day intervals for up to 50 days of age, the rats were studied to determine the effect of an LPD on the reproductive axis of the endocrine system. Daily monitoring of the body weight, as well as the consumption of food, kilocalories, and protein was conducted. The same parameters were followed over the identical time period in a group of animals desigated as controls which were fed a standard laboratory diet (SLD) containing 27% protein. The controls showed a linear growth rate over the 30-day experimental period. In comparison, the malnourished rats grew more slowly so that by 50 days of age, their mean body weight was 68.9 +/- 3.1 g as compared to 248.1 +/- 6.1 g for the controls. The daily food, kilocalorie, and protein intake by the experimental animals were also appreciably less. The pituitary gland, ventral prostate gland, testes and liver were smaller in the animals fed the LPD. This was observed as early as five days after initiating the dietary regimes and remained a consistent observation until the end of the experiment. In general, the absolute weights of these organs in the 50 day-old malnourished rats were similar to those found in 25 to 26-day-old animals fed the SLD. The relative weights of the pituitary gland and liver remained similar between the two animal groups. The testes and ventral prostate gland, however, were relatively smaller in the malnourished animals at nearly every time interval studied. On light microscopic examination of the testes, it was found that normal maturation of the germ cells failed to occur in all but one of the experimental animals, whereas maturation proceeded normally in the rats fed the SLD. Serum luteinizing hormone (LH), follicle stimulating hormone (FSH), prolactin (PRL), and testosterone were lower in the malnourished animals at all ages studied. These hormones not exhibit the fluctuations that were seen in the controls and are typical in rats that are becoming sexually mature. The effect of protein deficiency on the concentration of the pituitary gonadotrophins was more varied. FSH concentrations were consistently lower, PRL was moderately affected, and LH remained essentially unchanged. Hypothalamic LH-releasing hormone was measured and found to be significantly less in the rats fed the LPD at most of the time intervals examined. These results indicate that the hypothalamo-hypophyseal-gonadal axis is impaired when the consumption of proteins and calorie is decreased. The possible involvement of extrahypothlamic centers in the control of hormone secretion in the protein-deficient rat is discussed.
Anat Rec 1980 Jul
PMID:Growth patterns and hormonal profile of male rats with protein-calorie malnutrition. 677 47

Large MtTw15 tumors, which secrete growth hormone (GH) and prolactin (PRL), are composed of ovoid, elongated, and angular cells which demonstrated interdigitating processes and junctional complexes. The majority of the cells were essentially agranular, but two types of granulated cells were identifiable. One class of granulated cells contained moderate to sparse populations of round dense-cored granules measuring up to 250 nm in diameter. Rod-shaped to filamentous mitochondria with an electron-dense matrix were characteristic of a second class of granulated cells with plemorphic granules of various sizes and electron densities. Images of exocytotic release of the round dense-cored granules were frequently seen, but were not observed with the pleomorphic granules, many of which were judged to be lysosomes. Superimposition immunocytochemistry revealed hormones only in the granulated cells with round to ovoid granules. Morphometry indicated that hormone specific subpopulations of tumor cells can be identified since PRL secretory granules were significantly smaller than GH secretory granules (149 +/- 6 nm for PRL versus 221 +/- 9 nm for GH, P less than 0.001). The vast majority of immunopositive cells contained only GH or PRL, but a few were observed containing both hormones. Ovoid to irregular-shaped nuclei, large lipid inclusions, numerous free ribosomes and polyribosomes, moderate development of the rough endoplasmic reticulum, and prominent Golig profiles were characteristics of all cell types. Irrespective of the presence or absence of cytoplasmic granular elements, particles resembling viruses were encountered in many tumor cells, and these frequently appeared to be budding into the cisternae of the endoplasmic reticulum.
Anat Rec 1980 Mar
PMID:Heterogeneity of the MtTw15 mammosomatotropic tumor. II. Characterization of parenchymal cells by superimposition immunocytochemistry and electron microscopy. 699 24

Immunoreactive prolactin (PRL) cells in the adult male rat pituitary were observed by light microscopy to be scattered throughout the gland without special localization but sometimes to form small clusters consisting of five to ten cells. The cells had oval, polygonal, and cuplike shapes. Using the "superimposition technique," the fine structural properties of the PRL cells were examined on ultrathin sections just adjacent to the thick plastic section for immunostaining. Four cell types were distinguished: (1) oval, polygonal, and elongate cells with only small spherical granules, 130-200 nm in diameter; (2) oval or polygonal cells with both medium-sized spherical granules (250-300 nm) and about same size of polymorphic granules; (3) polygonal cells containing only large polymorphic granules (300-700 nm in maximal diameter); (4) cup-shaped PRL cells with spherical and small polymorphic granules. Furthermore, the prolactin immunoreactivity of these cell types was confirmed by the electron immunohistochemistry. Type 1 cells resemble, in fine structure, Kurosumi-Oota LH-gonadotrophs, but the former are not stained with anti-rat LH beta serum, but with anit-rat PRL serum. Although the functional relationship between these four types of cells is still unclear, it is concluded that the polymorphic shape of the granules is not necessarily an absolute criterion for identification of the PRL cell in the male.
Anat Rec 1982 Feb
PMID:Fine structural criteria of prolactin cells identified immunohistochemically in the male rat. 706 25

A fine structural study has confirmed earlier light microscopic observations indicating that prolactin cells are the only endocrine cells present in the main body of the rostral pars distalis of the adenohypophysis of Fundulus heteroclitus, a killifish common in New England coastal waters. Some ACTH cells occurred in thin plaques applied to the neurohypophysial trunk in the posterior part of the region. In freshwater-adapted specimens the volume occupied by the prolactin cell mass was larger than in saltwater-adapted specimens and contained larger prolactin cells. A paucity of contact specializations between the parenchymal cells may facilitate their spatial rearrangement as the prolactin cell population varies with changes in ambient salinity. Many fine neurohypophysial processes penetrated deeply into the rostral pars distalis and contained Type B (aminergic) nerve fibers believed to modulate prolactin secretion. These fibers ended mainly on the basement membrane that separates the neurohypophysial processes from the parenchyma. Synaptic contacts on prolactin cells were not observed but no prolactin cell appeared to be more than five cell widths from such a nerve terminal. The results emphasize the usefulness of the rostral pars distalis of this easily obtained and maintained teleost for studies of prolactin cell function.
Anat Rec 1980 Dec
PMID:Fine structure of the rostral pars distalis of the adenohypophysis of the killifish, Fundulus heteroclitus, in fresh and salt water. 721 12

We previously reported that residues 9-30 of the extracellular N-terminus domain of the rat FSH receptor, which has no homologous sequence in receptors for related pituitary glycoprotein hormones, represented a specific FSH binding domain. Further examination of its deduced primary structure identified another region, residues 300-315, which was also unique to the FSH receptor. To determine whether this region of the FSH receptor was involved in hormone binding, a synthetic peptide corresponding to residues 300-315 was studied with respect to its ability to bind FSH, as well as a series of nine overlapping synthetic peptides corresponding to the entire primary structure of the hormone specific FSH beta-subunit. 125I-FSH rec-(300-315) peptide bound to immobilized human, ovine and bovine FSH, but not to prolactin or ovalbumin. Of the nine synthetic peptides studied, binding was restricted to FSH beta residues 21-35, and to a much lesser extent (20%) to residues 11-25. All binding was abolished in the presence of excess solubilized FSH receptor. Earlier studies indicated that although FSH binds to FSH rec(9-30) peptide, residues 11-25 or 21-35 of the FSH beta-subunit were not involved. Our results suggest the FSH receptor N-terminus, extracellular residues 300-315, may define a FSH binding site, and that binding of FSH beta-subunit may occur via interactions with FSH beta 21-35 and 11-25.
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PMID:Identification of amino acid residues 300-315 of the rat FSH receptor as a hormone binding domain: evidence for its interaction with specific regions of FSH beta-subunit. 775 15


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