Decreased in vitro secretion of LH, FSH, and free alpha-subunits by pituitary cells from old male rats

1985 ◽  
Vol 249 (2) ◽  
pp. E145-E151
Author(s):  
M. R. Blackman ◽  
A. Mukherjee ◽  
P. D. Tsitouras ◽  
S. M. Harman
Keyword(s):  
Repeated Measures ◽  
Primary Cultures ◽  
In Vitro Release ◽  
Male Rats ◽  
Pituitary Cells ◽  
Cell Functions ◽  
Alpha Subunits ◽  
Old Rats ◽  
Lh Releasing Hormone

Various in vivo and in vitro pituitary-Leydig cell functions were examined in mature (5-8 mo) vs. old (22-25 mo) male Wistar rats. Old rats exhibited decreased serum concentrations of testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) (P less than 0.0025) but similar levels of prolactin (P less than 0.01) both before and 4 wk after castration. The in vitro release of LH, FSH, and free alpha-subunits was measured in primary cultures of dispersed anterior pituitary cells from both intact and castrated rats. During 48 h of incubation, basal secretion rates of the glycoproteins were decreased (P less than 0.001) from cells of both intact and castrated old rats. After stimulation with LH-releasing hormone (LRH) in single (10(-8) M) or multiple (10(-10) - 10(-7) M) doses, the total amounts of the glycoproteins secreted were also less from cells of both intact and castrated old rats. However, repeated measures analysis of variance revealed age-related hyporesponsivity to LRH stimulation only for LH secretion by cells from intact rats. The basal molar ratios of alpha/(LH + FSH) secreted by cells from intact but not castrated old rats were lower than those from cells of the corresponding mature rats. Moreover, after LRH stimulation (10(-10) - 10(-7) M), molar secretory ratios of alpha/(LH + FSH) decreased from cells of intact mature rats but increased from cells of intact old rats. These in vitro data suggest that the reduced serum LH and FSH levels in intact and castrated old male rats result in part from decreased secretion of these glycoproteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Ionophore A23187 partially reverses LH secretory defect of pituitary cells from old rats

1987 ◽  
Vol 253 (3) ◽  
pp. E233-E237
Author(s):  
R. S. Chuknyiska ◽  
M. R. Blackman ◽  
G. S. Roth
Keyword(s):  
Primary Cultures ◽  
Extracellular Calcium ◽  
Base Line ◽  
Ionophore A23187 ◽  
Pituitary Cells ◽  
Lh Release ◽  
Old Rats ◽  
Lh Releasing Hormone ◽  
Lh Secretion

We measured in vitro release of luteinizing hormone (LH) in the presence of 1.5 mM extracellular calcium, with and without LH-releasing hormone (LHRH; 10(-10) to 10(-7) M) or the ionophore A23187 (10(-7) to 10(-4) M), in primary cultures of anterior pituitary cells from intact mature (6 mo) and old (24 mo) male and intact and ovariectomized mature and old female Wistar rats. Base-line as well as LHRH- and A23187-mediated LH secretion was decreased from cells of old rats. However, exposure to A23187 led to a nearly twofold greater augmentation of LH release from cells of old rats, thus decreasing the apparent age-related LH secretory deficit by approximately one-half. We then measured LHRH-mediated (10(-8) M) vs. A23187-mediated (10(-4) M) LH release with and without extracellular calcium (0.08-1.5 mM). For cells from both mature and old rats, there was a similar calcium dependency for A23187- and LHRH-mediated LH release, with optimal LH secretion at 1.0-1.5 mM extracellular calcium concentrations. Again, both LHRH- and A23187-stimulated LH release was significantly lower and exposure to A23187 led to a greater increase in LH release from cells of old rats. Taken together with similar findings in other systems, these data suggest that the in vitro LH secretory defect of pituitary cells from old rats results in part from one or more defects in calcium mobilization and that such alterations may be a widespread manifestation of aging.

Excess in vitro prolactin secretion by pituitary cells from ovariectomized old rats

1984 ◽  
Vol 247 (4) ◽  
pp. E483-E488
Author(s):  
M. Haji ◽  
G. S. Roth ◽  
M. R. Blackman
Keyword(s):  
In Vitro Release ◽  
Prolactin Secretion ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Serum Prolactin ◽  
Pituitary Cells ◽  
Lh Release ◽  
Old Rats

Various in vivo and in vitro pituitary lactotropic and gonadotropic functions were measured in mature (6-7 mo, normally cycling) and old (24 mo, constant diestrus) female Wistar rats. Serum prolactin (PRL) levels were higher (P less than 0.001), whereas luteinizing hormone (LH) values were similar (P greater than 0.05) in old versus mature rats both before and 3 days after ovariectomy. Serum PRL levels decreased significantly (P less than 0.005) postovariectomy only in the mature rats. The in vitro release of PRL and LH was measured for 4 days in primary adenohypophyseal cell cultures from the ovariectomized rats. Both basal and 17 beta-estradiol (E2)-stimulated PRL release (P less than 0.001) and production (P less than 0.005) were greater by cells from old rats. In contrast, both basal release and E2-stimulated LH release were greater (P less than 0.001) by cells from mature rats. Peak PRL release by cells from both old and mature rats occurred after exposure to E2 doses 1/100th of those required for peak LH release. These data support the hypothesis that intrinsic derangements in anterior pituitary function contribute to the reproductive decline in aging female rats and that different pituitary cell types exhibit discordant age changes in estrogenic sensitivity.

Effects of in vivo gonadal hormone environment on in vitro hGRF-40-stimulated GH release

1985 ◽  
Vol 249 (3) ◽  
pp. E276-E280 ◽  
Author(s):  
W. S. Evans ◽  
R. J. Krieg ◽  
E. R. Limber ◽  
D. L. Kaiser ◽  
M. O. Thorner
Keyword(s):  
Female Rats ◽  
Male Rats ◽  
Gonadal Hormone ◽  
Base Line ◽  
Pituitary Cells ◽  
Intact Male ◽  
Castrate Male ◽  
Basal Release

The effects of gender and the gonadal hormone environment on basal and stimulated growth hormone (GH) release by dispersed and continuously perifused rat anterior pituitary cells were examined. Cells from intact male and diestrus day 2 female rats and from castrate male rats either untreated or treated with testosterone (T) or 17 beta-estradiol (E2) were used. Basal GH release (ng/min per 10(7) cells; mean +/- SE) by cells from diestrus day 2 female rats was less than by cells from castrate rats treated with T (4.3 +/- 0.6 vs. 11.4 +/- 2.7, respectively; P less than 0.025). No other differences in basal release were detected. Concentration-response relationships were documented between human GH-releasing factor 40 (hGRF-40; 0.03-100 nM given as 2.5-min pulses every 27.5 min) and GH release. Mean (+/- SE) overall GH release (ng/min per 10(7) cells) above base line was greater by cells from intact male rats (496 +/- 92) than by cells from castrate (203 +/- 37.3; P less than 0.0001), castrate and T-treated (348 +/- 52.8; P = 0.008), or castrate and E2-treated (58.1 +/- 6.8; P less than 0.001) male rats or by diestrus day 2 rats (68.6 +/- 9.5; P = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Сhanges in intracellular calcium concentration and mitochondrial potential in primary cultures of rat brain cells in acute mechanical injury

2018 ◽  
pp. 124-128
Author(s):  
И.А. Красильникова ◽  
З.В. Бакаева ◽  
В.Г. Пинелис ◽  
О.Ю. Лисина ◽  
А.М. Сурин
Keyword(s):  
Calcium Concentration ◽  
Primary Cultures ◽  
Mechanical Injury ◽  
Ionotropic Glutamate Receptors ◽  
Mitochondrial Potential ◽  
Microscopy Technique ◽  
Nmda Channels ◽  
Old Rats

Актуальность. Моделирование in vitro травматического повреждения мозга помогает выяснить патологические механизмы, ответственные за гибель клеток или их последующую дисфункцию в деталях, труднодостижимых in vivo. Цель. Определить изменения внутриклеточной концентрации свободного Са2+ ([Ca2+]i) и митохондриального потенциала (m) в первичной нейроглиальной культуре непосредственно в момент нанесения механической травмы. Методы и материалы. Методом флуоресцентной микроскопии отслеживали изменения [Ca2+]i) и m в первичной нейроглиальной культуре из коры головного мозга 1-2-дневных крыс. Возраст культуры в момент измерений 11-14 дней. Результаты. Обнаружено, что нейротравма вызывает скачок [Ca2+]i и совпадающее с ним по времени резкое падение m. Эти изменения затрагивали клетки, расположенные не далее 100мкм от границы травмы. Блокирование ионотропных глутаматных рецепторов NMDA-типа с помощью МК-801 снижало в 8,5 раз долю нейронов, имевших высокий подъем [Ca2+]i. Выводы. Поступления Са2+ в клетки при механическом повреждении первичной нейроглиальной культуры происходит преимущественно по NMDA-каналам и отчасти, вероятно, по АТФ-активируемым каналам. Background. In vitro modeling of traumatic brain injury helps clarifying pathological mechanisms responsible for cell death or their subsequent dysfunction in detail, which is difficult to accomplish in vivo. Aim. To determine changes in intracellular free Ca2+ concentration ([Ca2+]i) and mitochondrial potential (m) in a primary neuroglial culture during infliction of a mechanical injury (scratch). Methods and materials. Changes in [Ca2+]i and m in the primary neuroglial culture from the cerebral cortex of 1-2 day old rats were monitored using a fluorescence microscopy technique. Measurements were performed in 11-14-day old cultures. Results. Neurotrauma resulted in a sharp increase in [Ca2+]i and a synchronous profound drop of m. These changes affected cells located not farther than 100 µm from the boundary of the injury. Inhibition of NMDA-type ionotropic glutamate receptors with MK-801 reduced by approximately 8.5 times the proportion of neurons, which indicated a high [Ca2+]i rise. Conclusion. Са2+ influx into cells during mechanical injury of the primary neuroglial culture occurs predominantly through NMDA-channels and perhaps partially through ATP-activated channels.

scholarly journals Obestatin Partially Affects Ghrelin Stimulation of Food Intake and Growth Hormone Secretion in Rodents

Endocrinology ◽  
2007 ◽  
Vol 148 (4) ◽  
pp. 1648-1653 ◽  
Author(s):  
Philippe Zizzari ◽  
Romaine Longchamps ◽  
Jacques Epelbaum ◽  
Marie Thérèse Bluet-Pajot
Keyword(s):  
Food Intake ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Male Rats ◽  
Pituitary Cells ◽  
Gh Secretion ◽  
Freely Moving ◽  
Stimulation Of

Administration of ghrelin, an endogenous ligand for the GH secretagogue receptor 1a (GHSR 1a), induces potent stimulating effects on GH secretion and food intake. However, more than 7 yr after its discovery, the role of endogenous ghrelin remains elusive. Recently, a second peptide, obestatin, also generated from proteolytic cleavage of preproghrelin has been identified. This peptide inhibits food intake and gastrointestinal motility but does not modify in vitro GH release from pituitary cells. In this study, we have reinvestigated obestatin functions by measuring plasma ghrelin and obestatin levels in a period of spontaneous feeding in ad libitum-fed and 24-h fasted mice. Whereas fasting resulted in elevated ghrelin levels, obestatin levels were significantly reduced. Exogenous obestatin per se did not modify food intake in fasted and fed mice. However, it inhibited ghrelin orexigenic effect that were evident in fed mice only. The effects of obestatin on GH secretion were monitored in superfused pituitary explants and in freely moving rats. Obestatin was only effective in vivo to inhibit ghrelin stimulation of GH levels. Finally, the relationship between octanoylated ghrelin, obestatin, and GH secretions was evaluated by iterative blood sampling every 20 min during 6 h in freely moving adult male rats. The half-life of exogenous obestatin (10 μg iv) in plasma was about 22 min. Plasma obestatin levels exhibited an ultradian pulsatility with a frequency slightly lower than octanoylated ghrelin and GH. Ghrelin and obestatin levels were not strictly correlated. In conclusion, these results show that obestatin, like ghrelin, is secreted in a pulsatile manner and that in some conditions; obestatin can modulate exogenous ghrelin action. It remains to be determined whether obestatin modulates endogenous ghrelin actions.

Effects of leptin and neuropeptide-Y on transcript levels of thyrotropin beta and common alpha subunits of rat pituitary cells in vitro

Life Sciences ◽  
2004 ◽  
Vol 75 (24) ◽  
pp. 2897-2909 ◽  
Author(s):  
Indrajit Chowdhury ◽  
Jung-Tsun Chien ◽  
Abhijit Chatterjee ◽  
John Yuh-Lin Yu
Keyword(s):  
Neuropeptide Y ◽  
Pituitary Cells ◽  
Transcript Levels ◽  
Alpha Subunits ◽  
Rat Pituitary ◽  
Rat Pituitary Cells

Effects of crude and highly purified bovine inhibin (Mr 32 000 form) on gonadotrophin production by ovine pituitary cells in vitro: inhibin enhances gonadotrophin-releasing hormone-induced release of LH

1990 ◽  
Vol 127 (1) ◽  
pp. 149-159 ◽  
Author(s):  
S. Muttukrishna ◽  
P. G. Knight
Keyword(s):  
Primary Cultures ◽  
Suppressive Effect ◽  
Pituitary Cells ◽  
Dependent Manner ◽  
Α Subunit ◽  
Releasing Hormone ◽  
Lh Release ◽  
Gonadotrophin Releasing Hormone

ABSTRACT Primary cultures of ovine pituitary cells (from adult ewes) were used to investigate the actions of steroid-free bovine follicular fluid (bFF) and highly-purified Mr 32 000 bovine inhibin on basal and gonadotrophin-releasing hormone (GnRH)-induced release of FSH and LH. Residual cellular contents of each hormone were also determined allowing total gonadotrophin content/well to be calculated. As in rats, both crude and highly purified inhibin preparations promoted a dose (P < 0·001)- and time (P < 0·001)-dependent suppression of basal and GnRH-induced release of FSH as well as an inhibition of FSH synthesis, reflected by a fall in total FSH content/well. However, while neither inhibin preparation affected basal release of LH or total LH content/well, GnRH-induced LH release was significantly (P< 0·001) increased by the presence of either bFF (+ 75%) or highly-purified inhibin (+ 64%) in a dose- and time-dependent manner. This unexpected action of bFF on GnRH-induced LH release was abolished in the presence of 5 μl specific anti-inhibin serum, confirming that the response was indeed mediated by inhibin. Furthermore, neither oestradiol-17β (1 pmol/l–10 nmol/l) nor monomeric α-subunit of bovine inhibin (2·5–40 ng/ml) significantly affected basal or GnRH-induced release of LH. These in-vitro findings for the ewe lend support to a number of recent in-vivo observations and indicate that, in addition to its well-documented suppressive effect on the synthesis and secretion of FSH, inhibin may actually facilitate LH release in this species, in marked contrast to its action in the rat. Journal of Endocrinology (1990) 127, 149–159

Dopamine inhibits in vitro release of VIP and proliferation of VIP-immunoreactive pituitary cells

Neuropeptides ◽  
1996 ◽  
Vol 30 (1) ◽  
pp. 81-86 ◽  
Author(s):  
J Carretero ◽  
R.J Vazquez ◽  
M Santos ◽  
L Cacicedo ◽  
M Rubio ◽  
...  
Keyword(s):  
In Vitro Release ◽  
Pituitary Cells ◽  
Vitro Release

Inhibin-like activity in Sertoli cell culture media and testicular homogenates from rats of various ages

1987 ◽  
Vol 113 (1) ◽  
pp. 103-110 ◽  
Author(s):  
A. M. Ultee-van Gessel ◽  
F. H. de Jong
Keyword(s):  
Sertoli Cells ◽  
Culture Media ◽  
Reciprocal Relationship ◽  
Pituitary Cells ◽  
In Vitro Experiments ◽  
Old Rats ◽  
Lh Secretion

ABSTRACT The influence of age on testicular inhibin in untreated, neonatally hemicastrated and prenatally irradiated rats was studied using in-vivo and in-vitro experiments. In testicular cytosols prepared from 1-, 7-, 14-, 21-, 42- and 63-day-old rats concentrations of testicular inhibin could be measured with an in-vitro bioassay method using dispersed pituitary cells. Preparations of testicular cytosols caused a dose-dependent suppression of pituitary FSH secretion, whereas no effects were found on LH secretion. Testicular content of inhibin increased gradually with age, while after 14 days of age a relatively large increase of peripheral FSH concentrations occurred in all experimental groups. Neonatal hemicastration or prenatal irradiation resulted in decreased inhibin content of the testis and increased plasma FSH levels. The production of inhibin activity by Sertoli cells obtained from 7-, 14-, 21-, 42- and 63-day-old normal rats was measured during a 24-h incubation period on the third day of culture. The inhibin production per 106 plated Sertoli cells decreased rapidly after 14 days of age and the lowest production of inhibin was found in Sertoli cells from rats of 63 days of age. After preincubation with ovine FSH significantly larger amounts of inhibin activity were detected in spent media from 21-day-old rat testes. In contrast, suppression of inhibin production was found after preculture in the presence of testosterone at most of the ages studied. These data from in-vivo and in-vitro experiments indicate that a reciprocal relationship exists between pituitary FSH secretion and inhibin production before the age of 21 days. This relationship supports the concept that inhibin is a physiologically important modulator of FSH secretion before puberty, while the role of the large amount of testicular inhibin present at the older ages remains to be determined. J. Endocr. (1987) 113, 103–110

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