2,5-Hexanedione exposure alters the rat sertoli cell cytoskeleton *1I. Microtubules and seminiferous tubule fluid secretion

Rhodnius prolixus eliminates NaCl-rich urine at high rates following its infrequent but massive blood meals. This diuresis involves stimulation of Malpighian tubule fluid secretion by diuretic hormones released in response to distention of the abdomen during feeding. The precipitous decline in urine flow that occurs several hours after feeding has been thought until now to result from a decline in diuretic hormone release. We suggest here that insect cardioacceleratory peptide 2b (CAP2b) and cyclic GMP are part of a novel mechanism of anti-diuresis. Secretion rates of 5-hydroxytryptamine-stimulated Malpighian tubules are reduced by low doses of CAP2b or cyclic GMP. Maximal secretion rates are restored by exposing tubules to 1 mmol l-1 cyclic AMP. Levels of cyclic GMP in isolated tubules increase in response to CAP2b, consistent with a role for cyclic GMP as an intracellular second messenger. Levels of cyclic GMP in tubules also increase as urine output rates decline in vivo, suggesting a physiological role for this nucleotide in the termination of diuresis.

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Effects of hypophysectomy and subsequent FSH and testosterone treatment on inhibin production by adult rat testes

Journal of Endocrinology ◽

10.1677/joe.0.1050001 ◽

1985 ◽

Vol 105 (1) ◽

pp. 1-6 ◽

Cited By ~ 26

Author(s):

C. L. Au ◽

D. M. Robertson ◽

D. M. de Kretser

Keyword(s):

Seminiferous Tubule ◽

Hormonal Control ◽

Human Chorionic Gonadotrophin ◽

Experimental Conditions ◽

Adult Rats ◽

Adult Rat ◽

Fluid Production ◽

Tubule Fluid

ABSTRACT The hormonal control of inhibin production by adult rat testes was investigated using an in-vitro inhibin bioassay validated for the measurement of inhibin activity in charcoal-treated rat testicular extracts. The effect of hypophysectomy examined at 16 h, 3, 7 and 42 days after surgery showed a decrease in testicular inhibin content and seminiferous tubule fluid production by 7 days and a decrease in inhibin production by 42 days. Serum FSH and LH were suppressed 3 days after surgery. In 30-day chronically hypophysectomized adult rats treated for 3 days with twice daily s.c. injections of (a) human FSH (hFSH, 22 i.u./rat per day), (b) testosterone (5 mg/rat per day), (c) hFSH + testosterone (same doses as a and b), or (d) human chorionic gonadotrophin (hCG, 12 i.u./rat per day), hFSH or hFSH and testosterone stimulated an increase in testicular inhibin content but not in inhibin production or tubule fluid production. Testosterone and hCG had no effect on these parameters. It is concluded that in vivo, FSH alone stimulates an increase in testicular inhibin content. The failure to observe an increase in inhibin production in vivo is attributed to the suppression of seminiferous tubule fluid production under the same experimental conditions. J. Endocr. (1985) 105, 1–6

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CX43 expression, phosphorylation, and distribution in the normal and autoimmune orchitic testis with a look at gap junctions joining germ cell to germ cell

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00500.2010 ◽

2011 ◽

Vol 300 (1) ◽

pp. R121-R139 ◽

Cited By ~ 13

Author(s):

R.-Marc Pelletier ◽

Casimir D. Akpovi ◽

Li Chen ◽

Robert Day ◽

María L. Vitale

Keyword(s):

Cell Differentiation ◽

Gap Junctions ◽

Germ Cell ◽

Sertoli Cell ◽

Sertoli Cells ◽

Seminiferous Tubule ◽

Connexin 43 ◽

Cx43 Expression ◽

Cx43 Protein ◽

Cx43 Mrna

Spermatogenesis requires connexin 43 (Cx43).This study examines normal gene transcription, translation, and phosphorylation of Cx43 to define its role on germ cell growth and Sertoli cell's differentiation, and identifies abnormalities arising from spontaneous autoimmune orchitis (AIO) in mink, a seasonal breeder and a natural model for autoimmunity. Northern blot analysis detected 2.8- and a 3.7-kb Cx43 mRNA bands in seminiferous tubule-enriched fractions. Cx43 mRNA increased in seminiferous tubule-enriched fractions throughout development and then seasonally with the completion of spermatogenesis. Cx43 protein levels increased transiently during the colonization of the tubules by the early-stage spermatocytes. Cx43 phosphorylated (PCx43) and nonphosphorylated (NPCx43) in Ser368 decreased during the periods of completion of meiosis and Sertoli cell differentiation, while Cx43 mRNA remained elevated throughout. PCx43 labeled chiefly the plasma membrane except by stage VII when vesicles were also labeled in Sertoli cells. Vesicles and lysosomes in Sertoli cells and the Golgi apparatus in the round spermatids were NPCx43 positive. A decrease in Cx43 gene expression was matched by a Cx43 protein increase in the early, not the late, phase of AIO. Total Cx43 and PCx43 decreased with the advance of orchitis. The study makes a novel finding of gap junctions connecting germ cells. The data indicate that Cx43 protein expression and phosphorylation in Ser368 are stage-specific events that may locally influence the acquisition of meiotic competence and the Sertoli cell differentiation in normal testis. AIO modifies Cx43 levels, suggesting changes in Cx43-mediated intercommunication and spermatogenic activity in response to cytokines imbalances in Sertoli cells.

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CAP2b, a cardioacceleratory peptide, is present in Drosophila and stimulates tubule fluid secretion via cGMP

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1995.269.6.r1321 ◽

1995 ◽

Vol 269 (6) ◽

pp. R1321-R1326 ◽

Cited By ~ 21

Author(s):

S. A. Davies ◽

G. R. Huesmann ◽

S. H. Maddrell ◽

M. J. O'Donnell ◽

N. J. Skaer ◽

...

Keyword(s):

High Performance Liquid Chromatography ◽

Manduca Sexta ◽

High Performance ◽

Fluid Secretion ◽

Malpighian Tubules ◽

Cyclic Monophosphate ◽

Cgmp Signaling ◽

Camp And Cgmp ◽

Tubule Fluid ◽

Stimulation Of

A cardioacceleratory peptide, CAP2b, identified originally in the lepidopteran Manduca sexta, stimulates fluid secretion by Malpighian tubules of the dipteran Drosophila melanogaster. High-performance liquid chromatography analyses of adult D. melanogaster reveal the presence of a CAP2b-like peptide, that coelutes with M. sexta CAP2b and synthetic CAP2b and that has CAP2b-like effects on the M. sexta heart. CAP2b accelerates fluid secretion in tubules stimulated by adenosine 3',5'-cyclic monophosphate (cAMP) but has no effect on tubules stimulated by guanosine 3',5'-cyclic monophosphate (cGMP), implying that it acts through the latter pathway. By contrast, the action of leucokinin is additive to both cAMP and cGMP but not to thapsigargin, suggesting that leucokinin acts by the elevation of intracellular calcium. CAP2b stimulation elevates tubule cGMP levels but not those of cAMP. By contrast, leucokinin has no effect on levels of either cyclic nucleotide. Both CAP2b and cGMP increase transepithelial potential difference, suggesting that stimulation of vacuolar-adenosinetriphosphatase action underlies the corresponding increases in fluid secretion. Overall, the results show that a Drosophila CAP2b-related peptide acts to stimulate fluid secretion by Malpighian tubules through the cGMP-signaling pathway.

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