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Anatomical and functional gonadotrope networks in the teleost pituitary.

Golan M, Martin AO, Mollard P, Levavi-Sivan B - Sci Rep (2016)

Bottom Line: We found that in two fish species, namely tilapia and zebrafish, LH cells exhibit close cell-cell contacts and form a continuous network throughout the gland.These anatomical differences also manifest themselves at the functional level as evidenced by the effect of gap-junction uncouplers on gonadotropin release.The two gonadotropins were also found to be differently packaged within their corresponding cell types.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal Sciences, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.

ABSTRACT
Mammalian pituitaries exhibit a high degree of intercellular coordination; this enables them to mount large-scale coordinated responses to various physiological stimuli. This type of communication has not been adequately demonstrated in teleost pituitaries, which exhibit direct hypothalamic innervation and expression of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in distinct cell types. We found that in two fish species, namely tilapia and zebrafish, LH cells exhibit close cell-cell contacts and form a continuous network throughout the gland. FSH cells were more loosely distributed but maintained some degree of cell-cell contact by virtue of cytoplasmic processes. These anatomical differences also manifest themselves at the functional level as evidenced by the effect of gap-junction uncouplers on gonadotropin release. These substances abolished the LH response to gonadotropin-releasing hormone stimulation but did not affect the FSH response to the same stimuli. Dye transfer between neighboring LH cells provides further evidence for functional coupling. The two gonadotropins were also found to be differently packaged within their corresponding cell types. Our findings highlight the evolutionary origin of pituitary cell networks and demonstrate how the different levels of cell-cell coordination within the LH and FSH cell populations are reflected in their distinct secretion patterns.

No MeSH data available.


Related in: MedlinePlus

Large-scale structural gonadotrope networks in the zebrafish pituitary.Imaging of transgenic zebrafish pituitaries reveals that LH (a, LH:tagRFP line) and FSH (b,c, FSH:EGFP line) gonadotropes are arranged in three-dimensional networks. LH cells form a continuous population throughout the PPD (a). FSH cells are more loosely distributed throughout the PPD (b). A closer observation reveals that FSH cells form small aggregations in which cells contact each other (c). Both fish are adult females. Dorsal view, anterior-up, white line marks pituitary borders, PI – pars intermedia, RPD – rostral pars distalis. Bars in (a,b) −100 μm, (c) −20 μm.
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f2: Large-scale structural gonadotrope networks in the zebrafish pituitary.Imaging of transgenic zebrafish pituitaries reveals that LH (a, LH:tagRFP line) and FSH (b,c, FSH:EGFP line) gonadotropes are arranged in three-dimensional networks. LH cells form a continuous population throughout the PPD (a). FSH cells are more loosely distributed throughout the PPD (b). A closer observation reveals that FSH cells form small aggregations in which cells contact each other (c). Both fish are adult females. Dorsal view, anterior-up, white line marks pituitary borders, PI – pars intermedia, RPD – rostral pars distalis. Bars in (a,b) −100 μm, (c) −20 μm.

Mentions: In the zebrafish pituitary, similar trends were observed for the two gonadotrope types. Due to the small size of zebrafish pituitary we could perform imaging of the whole gland. Our transgenic models reveal that, as in tilapia, zebrafish LH cells form a continuous population throughout the gland (Fig. 2a) whereas FSH cells are more isolated from each other (Fig. 2b), although many of the membranes of FSH cells do contact neighboring cells (Fig. 2c).


Anatomical and functional gonadotrope networks in the teleost pituitary.

Golan M, Martin AO, Mollard P, Levavi-Sivan B - Sci Rep (2016)

Large-scale structural gonadotrope networks in the zebrafish pituitary.Imaging of transgenic zebrafish pituitaries reveals that LH (a, LH:tagRFP line) and FSH (b,c, FSH:EGFP line) gonadotropes are arranged in three-dimensional networks. LH cells form a continuous population throughout the PPD (a). FSH cells are more loosely distributed throughout the PPD (b). A closer observation reveals that FSH cells form small aggregations in which cells contact each other (c). Both fish are adult females. Dorsal view, anterior-up, white line marks pituitary borders, PI – pars intermedia, RPD – rostral pars distalis. Bars in (a,b) −100 μm, (c) −20 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4815020&req=5

f2: Large-scale structural gonadotrope networks in the zebrafish pituitary.Imaging of transgenic zebrafish pituitaries reveals that LH (a, LH:tagRFP line) and FSH (b,c, FSH:EGFP line) gonadotropes are arranged in three-dimensional networks. LH cells form a continuous population throughout the PPD (a). FSH cells are more loosely distributed throughout the PPD (b). A closer observation reveals that FSH cells form small aggregations in which cells contact each other (c). Both fish are adult females. Dorsal view, anterior-up, white line marks pituitary borders, PI – pars intermedia, RPD – rostral pars distalis. Bars in (a,b) −100 μm, (c) −20 μm.
Mentions: In the zebrafish pituitary, similar trends were observed for the two gonadotrope types. Due to the small size of zebrafish pituitary we could perform imaging of the whole gland. Our transgenic models reveal that, as in tilapia, zebrafish LH cells form a continuous population throughout the gland (Fig. 2a) whereas FSH cells are more isolated from each other (Fig. 2b), although many of the membranes of FSH cells do contact neighboring cells (Fig. 2c).

Bottom Line: We found that in two fish species, namely tilapia and zebrafish, LH cells exhibit close cell-cell contacts and form a continuous network throughout the gland.These anatomical differences also manifest themselves at the functional level as evidenced by the effect of gap-junction uncouplers on gonadotropin release.The two gonadotropins were also found to be differently packaged within their corresponding cell types.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal Sciences, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.

ABSTRACT
Mammalian pituitaries exhibit a high degree of intercellular coordination; this enables them to mount large-scale coordinated responses to various physiological stimuli. This type of communication has not been adequately demonstrated in teleost pituitaries, which exhibit direct hypothalamic innervation and expression of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in distinct cell types. We found that in two fish species, namely tilapia and zebrafish, LH cells exhibit close cell-cell contacts and form a continuous network throughout the gland. FSH cells were more loosely distributed but maintained some degree of cell-cell contact by virtue of cytoplasmic processes. These anatomical differences also manifest themselves at the functional level as evidenced by the effect of gap-junction uncouplers on gonadotropin release. These substances abolished the LH response to gonadotropin-releasing hormone stimulation but did not affect the FSH response to the same stimuli. Dye transfer between neighboring LH cells provides further evidence for functional coupling. The two gonadotropins were also found to be differently packaged within their corresponding cell types. Our findings highlight the evolutionary origin of pituitary cell networks and demonstrate how the different levels of cell-cell coordination within the LH and FSH cell populations are reflected in their distinct secretion patterns.

No MeSH data available.


Related in: MedlinePlus