The effect of stimulators and blockers of adrenergic receptors on LH secretion and cyclic nucleotide (cAMP and cGMP) production by porcine pituitary cells in vitro

The energy-dependent cyclic nucleotide cellular efflux is operative in numerous eukaryotic cells and could be mediated by multidrug resistance proteins MRP4, MRP5, and MRP8. In pituitary cells, however, the operation of export pumps and their contribution to the control of intracellular cyclic nucleotide levels were not studied previously. Here we show that cellular efflux of cyclic nucleotides was detectable in normal and immortalized GH3 pituitary cells under resting conditions and was enlarged after concurrent stimulation of cAMP and cGMP production with GHRH, corticotropin-releasing factor, vasoactive intestinal peptide, pituitary adenylate cyclase-activating polypeptide, and forskolin. In resting and stimulated cells, the efflux pumps transported the majority of de novo-produced cGMP, limiting its intracellular accumulation in a concentration range of 1–2 μm. In contrast, only a small fraction of cAMP was released and there was a time- and concentration-dependent accumulation of this messenger in the cytosol, ranging from 1–100 μm. Stimulation and inhibition of cGMP production alone did not affect cAMP efflux, suggesting the operation of two different transport pathways in pituitary cells. The rates of cAMP and cGMP effluxes were comparable, and both pathways were blocked by probenecid and progesterone. Pituitary cells expressed mRNA transcripts for MRP4, MRP5, and MRP8, whereas GH3 cells expressed only transcripts for MRP5. Down-regulation of MRP5 expression in GH3 cells decreased cGMP release without affecting cAMP efflux. These results indicate that cyclic nucleotide cellular efflux plays a critical role in elimination of intracellular cGMP but not cAMP in pituitary cells and that such selectivity is achieved by expression of MRP5.

Download Full-text

Intracellular pH on adrenergic-stimulated cAMP and cGMP production in rat pinealocytes

AJP Cell Physiology ◽

10.1152/ajpcell.1991.261.4.c642 ◽

1991 ◽

Vol 261 (4) ◽

pp. C642-C649 ◽

Cited By ~ 35

Author(s):

A. K. Ho ◽

M. Girard ◽

I. Young ◽

C. L. Chik

Keyword(s):

Intracellular Ph ◽

Ammonium Chloride ◽

Adrenergic Receptors ◽

Sodium Propionate ◽

Adrenergic Regulation ◽

Cyclic Monophosphate ◽

Cgmp Production ◽

Camp And Cgmp Production ◽

Camp And Cgmp

In rat pinealocytes, activation of alpha 1-adrenergic receptors leads to increases in intracellular pH (pHi). In this study, the role of pHi on adrenergic regulation of cyclic nucleotide accumulation was investigated using ammonium chloride, which increased pHi, and sodium propionate, which reduced pHi. Ammonium chloride significantly enhanced the norepinephrine-stimulated adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP) responses, while it selectively potentiated the isoproterenol (ISO)-stimulated cGMP response. Reduction of pHi by sodium propionate reduced the norepinephrine-stimulated cGMP accumulation by 70%, and its effect on the ISO-stimulated cGMP response was stimulatory. Treatment with sodium propionate effectively neutralized the enhancing effects of ammonium chloride on the adrenergic-stimulated cAMP and cGMP responses. These effects of sodium propionate and ammonium chloride on cyclic nucleotides appeared to reflect altered rate of synthesis, and they were also in part secondary to changes in intracellular Ca2+. Our findings indicate that the receptor-mediated changes in pHi may play an integral part in the adrenergic regulation of cAMP and cGMP production in rat pinealocytes.

Download Full-text

Steroid hormones regulate cAMP and cGMP production by porcine granulosa cells in vitro

The Journal of Steroid Biochemistry and Molecular Biology ◽

10.1016/0960-0760(93)90184-x ◽

1993 ◽

Vol 46 (5) ◽

pp. 573-577 ◽

Cited By ~ 13

Author(s):

Alexander V. Sirotkin ◽

Jozef Nitray

Keyword(s):

Steroid Hormones ◽

Granulosa Cells ◽

Cgmp Production ◽

Porcine Granulosa Cells ◽

Camp And Cgmp Production ◽

Camp And Cgmp

Download Full-text

Growth hormone and prolactin affect oxytocin, vasopressin, progesterone and cyclic nucleotide secretion by bovine granulosa cells in vitro

Journal of Endocrinology ◽

10.1677/joe.0.1430417 ◽

1994 ◽

Vol 143 (3) ◽

pp. 417-422 ◽

Cited By ~ 10

Author(s):

A V Sirotkin ◽

J Nitray

Keyword(s):

Growth Hormone ◽

Granulosa Cells ◽

Significant Influence ◽

Cyclic Nucleotide ◽

Structural Similarity ◽

High Dose ◽

Cgmp Production ◽

Progesterone Secretion ◽

Camp And Cgmp

Abstract The effects of growth hormone (GH) and prolactin (PRL) (1, 10, 100, 1000 or 10 000 ng/ml medium) on oxytocin, vasopressin, progesterone, cAMP and cGMP release by cultured bovine granulosa cells were studied. It was found that GH significantly stimulated oxytocin, vasopressin and cAMP but suppressed progesterone secretion. PRL tended to have the same pattern of action on nonapeptide, cAMP and steroid release, but its effect was not as great, with only a high supraphysiological dose (10 000 ng/ml) producing a statistically significant effect. No significant influence of GH on cGMP output was observed. Physiological doses of PRL (1, 10, 100 or 1000 ng/ml) significantly inhibited cGMP production whilst a high dose (10 000 ng/ml) resulted in stimulation. These observations suggested that GH may regulate ovarian oxytocin, vasopressin, progesterone and cAMP secretion. The effects of PRL on the release of these substances appeared to be non-specific, possibly resulting from its structural similarity to GH. Journal of Endocrinology (1994) 143, 417–422

Download Full-text

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

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1987.253.3.e233 ◽

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.

Download Full-text

Dependence of Electrical Activity and Calcium Influx-Controlled Prolactin Release on Adenylyl Cyclase Signaling Pathway in Pituitary Lactotrophs

Molecular Endocrinology ◽

10.1210/me.2005-0363 ◽

2006 ◽

Vol 20 (9) ◽

pp. 2231-2246 ◽

Cited By ~ 28

Author(s):

Arturo E. Gonzalez-Iglesias ◽

Yonghua Jiang ◽

Melanija Tomić ◽

Karla Kretschmannova ◽

Silvana A. Andric ◽

...

Keyword(s):

Protein Kinase ◽

Protein Kinase A ◽

Adenylyl Cyclase ◽

Guanylyl Cyclase ◽

Cyclic Nucleotide ◽

Action Potentials ◽

Soluble Guanylyl Cyclase ◽

Cgmp Production ◽

Camp And Cgmp ◽

Kinase A

Abstract Pituitary lactotrophs in vitro fire extracellular Ca2+-dependent action potentials spontaneously through still unidentified pacemaking channels, and the associated voltage-gated Ca2+ influx (VGCI) is sufficient to maintain basal prolactin (PRL) secretion high and steady. Numerous plasma membrane channels have been characterized in these cells, but the mechanism underlying their pacemaking activity is still not known. Here we studied the relevance of cyclic nucleotide signaling pathways in control of pacemaking, VGCI, and PRL release. In mixed anterior pituitary cells, both VGCI-inhibitable and -insensitive adenylyl cyclase (AC) subtypes contributed to the basal cAMP production, and soluble guanylyl cyclase was exclusively responsible for basal cGMP production. Inhibition of basal AC activity, but not soluble guanylyl cyclase activity, reduced PRL release. In contrast, forskolin stimulated cAMP and cGMP production as well as pacemaking, VGCI, and PRL secretion. Elevation in cAMP and cGMP levels by inhibition of phosphodiesterase activity was also accompanied with increased PRL release. The AC inhibitors attenuated forskolin-stimulated cyclic nucleotide production, VGCI, and PRL release. The cell-permeable 8-bromo-cAMP stimulated firing of action potentials and PRL release and rescued hormone secretion in cells with inhibited ACs in an extracellular Ca2+-dependent manner, whereas 8-bromo-cGMP and 8-(4-chlorophenyltio)-2′-O-methyl-cAMP were ineffective. Protein kinase A inhibitors did not stop spontaneous and forskolin-stimulated pacemaking, VGCI, and PRL release. These results indicate that cAMP facilitates pacemaking, VGCI, and PRL release in lactotrophs predominantly in a protein kinase A- and Epac cAMP receptor-independent manner.

Download Full-text

Neurokinin B regulates reproduction via inhibition of kisspeptin in a teleost, the striped bass

Journal of Endocrinology ◽

10.1530/joe-16-0575 ◽

2017 ◽

Vol 233 (2) ◽

pp. 159-174 ◽

Cited By ~ 12

Author(s):

Nilli Zmora ◽

Ten-Tsao Wong ◽

John Stubblefield ◽

Berta Levavi-Sivan ◽

Yonathan Zohar

Keyword(s):

Striped Bass ◽

Brain Slices ◽

Neuronal Population ◽

Minor Effect ◽

Pituitary Cells ◽

Neurokinin B ◽

A Minor ◽

Lh Secretion

Kisspeptin and neurokinin B (NKB) are neuropeptides co-expressed in the mammalian hypothalamus and coordinately control GnRH signaling. We have found that Nkb and kisspeptin neurons are distinct in the teleost, striped bass (STB) and capitalized on this phenomenon to study the mode of action of Nkb and its related neuropeptide-F (Nkf), both of which are encoded by the tac3 gene. In vitro brain slices and in vivo administration studies revealed that Nkb/f consistently downregulated kiss2, whereas antagonist (AntD) administration restored this effect. Overall, a minor effect was noted on gnrh1 expression, whereas Gnrh1 content in the pituitaries was reduced after Nkb/f treatment and increased with AntD. Concomitantly, immunostaining demonstrated that hypothalamic Nkb neurons border and densely innervate the largest kiss2 neuronal population in the hypothalamus, which also coexpresses Nkb receptor. No expression of Nkb receptor or Nkb neuronal projections was detected near/in Gnrh1 soma in the preoptic area. At the level of the pituitary, however, the picture was more complex: both Nkb/f and AntD upregulated lhb and fshb expression and Lh secretion in vivo. Together with the stimulatory effect of Nkb/f on Lh/Fsh secretion from pituitary cells, in vitro, this may indicate an additional independent action of Nkb/f within the pituitary, in which the hypothalamic pathway is more dominant. The current study demonstrates that Nkb/f utilizes multiple pathways to regulate reproduction in the STB and that in the brain, Nkb mainly acts as a negative modulator of kiss2 to regulate the release of Gnrh1.

Download Full-text

The influence of GnRH, oxytocin and vasoactive intestinal peptide on the secretion of β-endorphin and production of cAMP and cGMP by porcine pituitary cells in vitro

Animal Reproduction Science ◽

10.1016/s0378-4320(01)00176-2 ◽

2002 ◽

Vol 69 (1-2) ◽

pp. 125-137 ◽

Cited By ~ 6

Author(s):

I Bogacka ◽

G Siawrys ◽

S Okrasa ◽

T Kaminski ◽

J Przala

Keyword(s):

Vasoactive Intestinal Peptide ◽

Pituitary Cells ◽

Camp And Cgmp

Download Full-text

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

Journal of Endocrinology ◽

10.1677/joe.0.1130103 ◽

1987 ◽

Vol 113 (1) ◽

pp. 103-110 ◽

Cited By ~ 15

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

Download Full-text