The comparative aspects of hystricomorph subplacenta: potential endocrine organ

BMC Zoology ◽  
2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Maria Angelica Miglino ◽  
Gustavo de Sá Schiavo Matias ◽  
Nathia Nathaly Rigoglio ◽  
Jessica Borghesi ◽  
Taís Harumi de Castro Sasahara ◽  
...  
Keyword(s):  
Guinea Pigs ◽  
Hormone Secretion ◽  
Chorionic Villus ◽  
Secretory Activity ◽  
Steroidogenic Enzymes ◽  
Unusual Structure ◽  
Hormone Synthesis ◽  
Trophoblastic Cells ◽  
Considerable Controversy ◽  
Near Term

Abstract Background The placenta of hystricomorph rodents, lagomorphs and some primates includes an unusual structure, termed a subplacenta, which essentially consists of trophoblastic cells located deep to the central implantation site within the area of decidualization. It has been suggested that the subplacenta is functionally important, although considerable controversy remains on the issue. In this context, our objective was to compare the architecture and structure of the subplacentas of different hystricomorph species, to investigate the possibility that it is active in hormone synthesis. Methods In total, the placentas of 3 capybaras (Hydrochaeris hydrochaeris), 2 pacas (Agouti paca), 5 agoutis (Dasyprocta leporina), 5 rock cavies (Kerodon rupestris) and 3 guinea pigs (Cavia porcellus) at different stages of pregnancy (early, middle and near term) were used for gross and microscopic examination. This included the preparation of latex injection casts, immunohistochemistry for steroidogenic enzymes, scanning and transmission electron microscopy. Tissue steroid concentrations were also determined. Results The gross morphology and microvascular arrangement of the subplacentas were similar among the hystricomorphs studied including ultra-structural verification of cytotrophoblast and syncytiotrophoblast in all species. In guinea pigs, trophoblast cells exhibited characteristics consistent with intense metabolic and secretory activity in general. However, immuno-histochemical evidence also indicated that subplacental trophoblast expressed key steroidogenic enzymes, mainly in the chorionic villus region, consistent with tissue steroid concentrations. Conclusions The subplacentas within placentas of hystricomorph rodent species are structurally similar and, in guinea pigs, have potential for steroid hormone secretion from, at least the early stages of pregnancy.

Ultrastructural morphology of nontumorous lactotrophs in human pituitaries exposed to high prolactin levels

1987 ◽  
Vol 45 ◽  
pp. 896-897
Author(s):  
S. Jalalah ◽  
K. Kovacs ◽  
E. Horvath
Keyword(s):  
Anterior Pituitary ◽  
Secretory Activity ◽  
Pituitary Hormones ◽  
Feedback Mechanism ◽  
Endocrine Activity ◽  
Hormone Synthesis ◽  
Anterior Pituitary Hormones ◽  
Negative Feedback Mechanism ◽  
Ultrastructural Morphology ◽  
Transmission Electron

Lactotrophs, as many other endocrine cells, change their morphology in response to factors influencing their secretory activity. Secretion of prolactin (PRL) from lactotrophs, like that of other anterior pituitary hormones, is under the control of the hypothalamus. Unlike most anterior pituitary hormones, PRL has no apparent target gland which could modulate the endocrine activity of lactotrophs. It is generally agreed that PRL regulates its own release from lactotrophs via the short loop negative feedback mechanism exerted at the level of the hypothalamus or the pituitary. Accordingly, ultrastructural morphology of lactotrophs is not constant; it is changing in response to high PRL levels showing signs of suppressed hormone synthesis and secretion.By transmission electron microscopy and morphometry, we have studied the morphology of lactotrophs in nontumorous (NT) portions of 7 human pituitaries containing PRL-secreting adenoma; these lactotrophs were exposed to abnormally high PRL levels.

Effects of lung expansion on lung liquid production in vitro by lungs from fetal guinea-pigs. II. Evidence for generation of an inhibitory factor

1996 ◽  
Vol 8 (3) ◽  
pp. 347 ◽  
Author(s):  
PG Nelson ◽  
AM Perks
Keyword(s):  
Body Weight ◽  
Guinea Pigs ◽  
Inhibitory Factor ◽  
Dilution Method ◽  
Lung Fluid ◽  
Lung Expansion ◽  
Fluid Production ◽  
Near Term ◽  
Lung Liquid

Lungs from near-term fetal guinea-pigs were supported in vitro for 3 h; lung liquid production was measured by a dye-dilution method using Blue Dextran 2000 [fetuses 63 +/- 2 days of gestation, 97.6 +/- 19.8 (SD) g body weight]. Preparations were incubated in pairs taken from the same mother. Twenty lungs incubated in pairs without treatment (controls) showed no significant changes in fluid production throughout incubation (analysis of variance; regression analysis); rates in successive hours were: first lung, 1.36 +/- 0.39, 1.09 +/- 0.34 and 1.27 +/- 0.42 ml/kg body weight per h; second lung, 1.46 +/- 0.52, 1.09 +/- 0.41 and 1.18 +/- 0.43 ml/kg body weight per h. Twenty lungs were incubated similarly in pairs, but after one hour one lung from each pair was expanded with Krebs-Henseleit saline in volumes approximating those of the first breath (68 +/- 10% of lung volume). The expanded lungs began to reabsorb fluid immediately after expansion; the untreated lungs also stopped production or reached reabsorption by the final hour. Rates in successive hours were: expanded lungs; before expansion, 1.00 +/- 0.21, after expansion, -0.23 +/- 0.17 and 0.14 +/- 0.09 ml/kg body weight per h; unexpanded lungs, 1.27 +/- 0.49, 0.02 +/- 0.01 and -0.01 +/- 0.004 ml/kg body weight per h. The decrease in production was significant for each type of lung. The effects persisted in both expanded and unexpanded lungs in the presence of 1.78 x 10(-5) M phentolamine (n = 12; 70 +/- 2% expansion). The results suggest that expansion of the lungs at birth may release an unknown inhibitory factor, provisionally termed Expansion Factor (EF), within the lungs; this agent, probably not a catecholamine, can change lung fluid production into reabsorption and may partly account for the failure of beta-antagonists to prevent fluid reabsorption at delivery.

Developmental regulation of chloride/formate exchange in guinea pig proximal tubules

1995 ◽  
Vol 269 (5) ◽  
pp. F686-F695 ◽  
Author(s):  
E. N. Guillery ◽  
D. J. Huss
Keyword(s):  
Proximal Tubule ◽  
Guinea Pigs ◽  
Developmental Regulation ◽  
Membrane Vesicles ◽  
Proton Gradient ◽  
Disulfonic Acid ◽  
Postnatal Adaptation ◽  
Near Term ◽  
22Na Uptake ◽  
Nacl Excretion

There is a marked decrease in renal NaCl excretion immediately following birth. To test the hypothesis that parallel upregulation of the proximal tubule apical membrane Na+/H+ and Cl-/formate exchangers contributes to this postnatal adaptation, we measured exchanger activities in brush-border membrane vesicles from near-term fetal, 3- to 5-day-old, and adult guinea pigs. Uptake of 36Cl- was measured in the presence of an outwardly directed formate gradient and an inwardly directed proton gradient. In other experiments, 22Na+ uptake was measured in the presence of an outwardly directed proton gradient. 36Cl- uptake was inhibitable by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) and furosemide, and 22Na+ uptake was inhibitable by amiloride. Maximal uptakes of both 36Cl- and 22Na+ exceeded 2-h equilibration values in vesicles from newborn and adult guinea pigs, suggesting transporter-mediated uptake. Such overshoots were not seen with the vesicles from fetuses. Compared with vesicles from fetuses, the initial velocity of formate-driven 36Cl- uptake was 73% greater in vesicles from newborns and 65% greater in vesicles from adults. These results demonstrate parallel upregulation of proximal tubule Na+/H+ and Cl-/formate exchanger activities immediately after birth. This parallel upregulation may be important in mediating the postnatal decrease in renal NaCl excretion.

Chronic effects of caerulein and secretin on the endocrine pancreas of the rat

1983 ◽  
Vol 244 (5) ◽  
pp. G541-G545
Author(s):  
T. Yamada ◽  
J. Brunstedt ◽  
T. Solomon
Keyword(s):  
Dna Content ◽  
Endocrine Pancreas ◽  
Hormone Secretion ◽  
Hormone Synthesis ◽  
Chronic Effects ◽  
Islet Hormone ◽  
Hormone Responses ◽  
Insulin Responses ◽  
Isolated Rat

Secretin and caerulein increase pancreatic somatostatin content when administered chronically to rats. We examined whether this change occurs in vitro and results in altered islet hormone secretion. Pancreatic somatostatin content was increased from 0.25 +/- 0.01 (mean +/- SE) to 0.41 +/- 0.03 nmol/pancreas (P less than 0.001, n = 8) in rats treated for 10 days with caerulein (1 microgram/kg) and secretin (100 micrograms/kg) every 8 h. Somatostatin content in isolated rat pancreatic islets cultured for 10 days in medium containing caerulein and secretin (10(-9) M) was also increased (2.5 +/- 1.0 to 3.6 +/- 1.3 fmol/islet, P less than 0.02, n = 7), although islet DNA content was unchanged. Small increases in glucagon content were observed in both systems, but insulin content was not changed. Isolated perfused pancreases from peptide-treated rats and islets cultured in medium containing the two peptides exhibited significantly greater somatostatin responses to 5 mM glucose and 20 mM theophylline. Insulin responses to glucose and theophylline stimulation were not altered, although basal accumulation of insulin was greater in islet cultures with added caerulein and secretin. These results suggest that caerulein and secretin have direct actions on islet hormone synthesis with effects on hormone responses to stimulation.

SEQUENTIAL STUDY OF THE IMPAIRMENT OF THYROID FUNCTION IN THE EARLY STAGE OF SUBACUTE THYROIDITIS

1974 ◽  
Vol 77 (1) ◽  
pp. 26-34 ◽  
Author(s):  
Daniel Glinoer ◽  
Nicole Puttemans ◽  
André J. Van Herle ◽  
Monique Camus ◽  
André M. Ermans
Keyword(s):  
Thyroid Function ◽  
Early Stage ◽  
Hormone Secretion ◽  
Secretory Activity ◽  
Subacute Thyroiditis ◽  
Partial Recovery ◽  
Serum Thyroglobulin ◽  
Serum Thyroxine ◽  
Sequential Study ◽  
Clinical Onset

ABSTRACT A sequential study of various parameters of thyroid metabolism has been carried out in 2 patients during the weeks following the clinical onset of subacute thyroiditis, the aim being to define the nature and extent of the anomalies of thyroid function. In the early stage, serum thyroxine, protein bound iodine and T3 resin uptake levels were in the thyrotoxic range. In both cases, the serum thyroxine values further decreased with a half-life of 7 days and reached the hypothyroid range at the 6–7th week. Both 131I uptake and TSH plasma levels were found to be low and concomitantly rose at the 6–7th week. In one patient the serum thyroglobulin level was strikingly elevated at the beginning and then fell fairly rapidly; however in both patients, the serum thyroglobulin values remained abnormal. The present study confirmed the concept of a sudden release of preformed hormone stores. Furthermore, the following points were evident: a) marked and transient release of thyroglobulin; b) interruption of the secretory activity during at least 7 weeks; c) adequate functioning of the pituitary-thyroid control mechanism and d) partial recovery of the thyroidal iodine uptake at a time when the hormone secretion was still undetectable.

Lung-liquid production in vitro by lungs from fetal guinea pigs: effects of amiloride on responses to aldosterone

1997 ◽  
Vol 75 (7) ◽  
pp. 1147-1154 ◽  
Author(s):  
A. M. Perks ◽  
M. Stockbrocks ◽  
D. C. Chuang ◽  
I. Vonder Muhll ◽  
P. W. Kindler
Keyword(s):  
Regression Analysis ◽  
Guinea Pigs ◽  
Response Curve ◽  
Plasma Concentrations ◽  
Dilution Method ◽  
M 10 ◽  
Fluid Production ◽  
Near Term ◽  
Lung Liquid

Lungs from near-term fetal guinea pigs (62 ± 2 days of gestation) were supported in vitro for 3 h; lung-liquid production was monitored by a dye-dilution method based on Blue Dextran 2000. Untreated preparations produced fluid at 1.26 ± 0.14 mL∙kg−1 body mass∙h−1, with no significant change over the ensuing hours (ANOVA, regression analysis; n = 16). Experimental preparations received aldosterone at plasma concentrations reported to be present at birth. Aldosterone produced rapid, significant reductions in fluid production, and occasionally reabsorptions, which persisted beyond treatment. Reductions during treatment were as follows: 10−8 M aldosterone, 90.8 ± 4.9% (P < 0.001; n = 4); 2 × 10−9 M aldosterone, 64.1 ± 16.6% (P < 0.05–0.001; n = 6), and 7 × 10−10 M aldosterone, 48.6 ± 11.7% (P < 0.005–0.001; n = 6). The linear log dose response curve (r = 0.99) showed a theoretical threshold at 3.4 × 10−11 M aldosterone. Responses to 7 × 10−10 M aldosterone were abolished by 10−6 M amiloride. At the highest concentration of aldosterone (10−8 M), 10−6 M amiloride significantly reduced responses, and the changes were no longer significant by ANOVA. At both high and low aldosterone concentrations, responses with amiloride were significantly lower than those without amiloride (ANOVA, P < 0.03–0.04). Amiloride controls and untreated preparations showed no significant changes in fluid production. It is concluded that aldosterone at plasma concentrations present at birth can cause reductions in lung-liquid production or reabsorption through effects on amiloride-sensitive Na+ channels, and that the responses are remarkably rapid.

Hormonal control of thyrotropin and growth hormone secretion in a human thyrotrope pituitary adenoma studied in vitro

1988 ◽  
Vol 119 (2) ◽  
pp. 283-290 ◽  
Author(s):  
Marie Simard ◽  
Carol J. Mirell ◽  
A. Eugene Pekary ◽  
Jerry Drexler ◽  
Kalman Kovacs ◽  
...  
Keyword(s):  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Gel Filtration ◽  
Secretory Activity ◽  
Hormonal Control ◽  
Messenger Rnas ◽  
Cell Adenoma ◽  
Α Subunit ◽  
Gh Secretion

Abstract. Pituitary thyrotrope tumours are a rare cause of hyperthyroidism. Prior in vitro studies of these tumours have revealed various patterns of differentiation and secretory activity. We have characterized the histological, biochemical, molecular and physiological features of a thyrotrope adenoma in order to define its origin and autonomy. Histochemical and electron micrograph findings confirmed the diagnosis of a thyrotrope cell adenoma. Immunostaining was positive for TSH and GH in the cytoplasm of the adenoma cells. Tissue extracts contained TSH-IR which co-eluted with authentic hTSH when analysed by gel filtration. Tumour fragments studied in a tissue culture system secreted TSH, α-subunit and GH. TRH (30 nmol/l) stimulated TSH and GH secretion. T3 (1.5 nmol/l) inhibited GH release and had no effect on TSH secretion. GnRH (50 nmol/l), dexamethasone (10−4 mol/l), SRIH (1 μmol/l) and TRH-glycine, a tetrapeptide precursor of TRH, stimulated TSH release. Dexamethasone inhibited GH and α-subunit secretion. Stable transcripts for α- and β-subunits of TSH and GH messenger RNAs were detected by molecular hybridization in cytosolic fractions. Immunohistochemistry, in vitro secretory function, and mRNA analysis suggest multidirectional differentiation of the tumour cells. TRH-glycine may have a direct stimulatory effect upon pituitary thyrotropes.

Growth hormone secretion in the guinea-pig

1990 ◽  
Vol 124 (3) ◽  
pp. 371-380 ◽  
Author(s):  
B. Gabrielsson ◽  
K. M. Fairhall ◽  
I. C. A. F. Robinson
Keyword(s):  
Growth Hormone ◽  
Guinea Pig ◽  
Guinea Pigs ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Physiological Control ◽  
Gh Secretion ◽  
Dose Dependent Fashion ◽  
Growth Promoting ◽  
Dose Dependent

ABSTRACT The guinea-pig is unusual in that it continues to grow at a normal rate after hypophysectomy. Although its pituitary gland appears to contain a GH, this has not been isolated or characterized, and nothing is known about its secretion or physiological control. We have identified guinea-pig GH, established a sensitive heterologous radioimmunoassay and adapted our automatic blood microsampling method to study spontaneous GH secretion in this species. In male guinea-pigs, GH is released in an episodic pattern, reminiscent of the rat. Large multicomponent pulses of GH secretion occur every 3–4 h between periods of low or undetectable GH release, whereas most females showed a more uniform pulsatile pattern with pulses every 1–2 h. GH was released in response to GH-releasing factor (GRF) injections (2, 10 or 20 μg [Nle27]-GRF(1–29)NH2) in a dose-dependent fashion, and i.v. infusion of somatostatin (50 μg/h) blocked spontaneous GH pulses, eliciting a rebound release (from 2·0±0·8 (s.e.m.) to 36±17 μg/l 30 min after stopping the infusion). Infusions of a GH-releasing hexapeptide (100 or 400 μg/h for 4 h) also released GH. These results provide the first description of the pattern of GH release in the guinea-pig, and suggest that the striking episodic pattern is controlled by the same hypothalamic peptides that regulate GH in other species. Since the guinea-pig grows well in the absence of GH, this species may use GH for its metabolic, rather than growth-promoting actions. The guinea-pig may well prove a useful model, now that methods are available for studying its endogenous GH secretion. Journal of Endocrinology (1990) 124, 371–380

Reabsorption of lung liquid produced by 2,4-dinitrophenol in in vitro lungs from fetal guinea pigs

1993 ◽  
Vol 71 (1) ◽  
pp. 1-11 ◽  
Author(s):  
A. M. Perks ◽  
T. Ruiz ◽  
B. Chua ◽  
I. Vonder Muhll ◽  
P. M. Kindler ◽  
...  
Keyword(s):  
Body Weight ◽  
Regression Analysis ◽  
Guinea Pigs ◽  
Dilution Technique ◽  
Dye Dilution ◽  
Fluid Production ◽  
Oxidative Processes ◽  
Near Term ◽  
Lung Liquid

Lungs from near-term fetal guinea pigs (62 ± 2 days of gestation) were supported in vitro for 3 h, and lung liquid production was measured by a dye dilution technique. Twelve untreated preparations produced fluid at 1.54 ± 0.29 mL∙kg−1 body weight∙h−1 during the 1st h, with no significant changes in later hours. Twelve preparations treated with 2 × 10−4 M 2,4-dinitrophenol (DNP) showed strong reabsorptions (significant, ANOVA and regression analysis); total loss of lactate from the preparations doubled (significant, same tests). In 12 additional preparations, increasing DNP fivefold did not abolish reabsorption; results resembled those at the lower concentration. Amiloride at 10−6 M abolished reabsorptions after 2 × 10−4 M DNP, although fluid production still halted (n = 6; reductions significant, same tests). Amiloride alone had no effect (n = 6); untreated controls showed no change (n = 6). Similarly, 10−4 M sodium iodoacetate virtually abolished reabsorptions after 2 × 10−4 M DNP, although fluid production still stopped (n = 6; reductions significant, same tests). Iodoacetate alone only reduced fluid production (n = 6; significant, same tests); untreated controls showed no change (n = 6). The results suggest that reabsorptions seen after inhibition of oxidative processes depend on amiloride-sensitive Na+ channels and glycolytic metabolism.Key words: fetus, lung liquid, 2,4-dinitrophenol, amiloride, iodoacetate.

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