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Central cholinergic signal-mediated neuroendocrine regulation of vasopressin and oxytocin in ovine fetuses.

Shi L, Mao C, Zeng F, Zhang Y, Xu Z - BMC Dev. Biol. (2008)

Bottom Line: I.c.v. carbachol significantly increased fetal plasma AVP and OT concentrations.The results indicate that the central cholinergic mechanism is established and functional in the regulation of the hypothalamic neuropeptides during the final trimester of pregnancy.This provides evidence for a functional link between the development of central cholinergic mechanisms and hypothalamic neuropeptide systems in the fetus.

View Article: PubMed Central - HTML - PubMed

Affiliation: Perinatal Biology Center, Soochow University School of Medicine, Suzhou 215007, PR China. lshi@llu.edu

ABSTRACT

Background: The hypothalamic-neurohypophysial system plays a fundamental role in the maintenance of body fluid homeostasis by secreting arginine vasopressin (AVP) and oxytocin (OT) in response to a variety of signals, including osmotic and nonosmotic stimuli. It is well established that central cholinergic mechanisms are critical in the regulation of cardiovascular responses and maintenance of body fluid homeostasis in adults. Our recent study demonstrated that intracerebroventricular (i.c.v.) injection of carbachol elicited an increase of blood pressure in the near-term ovine fetuses. However, in utero development of brain cholinergic mechanisms in the regulation of the hypothalamic neuropeptides is largely unknown. This study investigated AVP and OT neural activation in the fetal hypothalamus induced by central carbachol.

Results: Chronically prepared near-term ovine fetuses (0.9 gestation) received an i.c.v. carbachol (3 microg/kg). Fetal blood samples were collected for AVP and OT assay, and brains were used for c-fos mapping studies. I.c.v. carbachol significantly increased fetal plasma AVP and OT concentrations. Intense FOS immunoreactivity (FOS-ir) was observed in the fetal supraoptic nuclei (SON) and paraventricular nuclei (PVN) in the hypothalamus. Double labeling demonstrated that a number of AVP- and OT-containing neurons in the fetal SON and PVN were expressing c-fos in response to central carbachol.

Conclusion: The results indicate that the central cholinergic mechanism is established and functional in the regulation of the hypothalamic neuropeptides during the final trimester of pregnancy. This provides evidence for a functional link between the development of central cholinergic mechanisms and hypothalamic neuropeptide systems in the fetus.

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FOS-ir and AVP-ir (or OT-ir) in the SON and PVN following i.c.v. carbachol. A: double labeling of FOS-ir and AVP-ir in the SON. B: double labeling of FOS-ir and OT-ir in the PVN. Solid arrows indicate co-localization of FOS-ir and AVP-ir (or OT-ir). Open arrows indicate AVP-ir (or OT-ir) positive cells without FOS-ir. Dash arrows indicate positive FOS-ir outside of AVP- (or OT-ir) containing cells. Scale bar = 10 μm.
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Figure 5: FOS-ir and AVP-ir (or OT-ir) in the SON and PVN following i.c.v. carbachol. A: double labeling of FOS-ir and AVP-ir in the SON. B: double labeling of FOS-ir and OT-ir in the PVN. Solid arrows indicate co-localization of FOS-ir and AVP-ir (or OT-ir). Open arrows indicate AVP-ir (or OT-ir) positive cells without FOS-ir. Dash arrows indicate positive FOS-ir outside of AVP- (or OT-ir) containing cells. Scale bar = 10 μm.

Mentions: Double labeling showed that there was no FOS-ir in AVP-containing and OT-containing cells in the brain of control fetuses. However, co-localization of FOS-ir in many AVP and OT neurons was detected in both sides of the SON and PVN following i.c.v. carbachol in the fetal hypothalamus (Figure 5). Although many AVP and OT neurons were co-localized with positive FOS-ir, there were some AVP and OT cells not labeled with FOS-ir. There was no difference in the total counting of AVP-ir and OT-ir in the SON and PVN between the control and the treated fetuses (all P > 0.05). Double labeling of FOS-ir and AVP-ir in the SON was significantly higher in the carbachol-treated fetuses than in the control animals (t = 6.78, P < 0.01). 82% of the AVP (+) neurons in the SON were FOS (+) in the carbachol treated fetuses. However, very few of FOS (+) cells in the SON (about 6%) were not AVP-containing neurons. Also, double labeling of FOS-ir and OT-ir in the PVN was significantly higher in the carbachol-treated fetuses than in the control animals (t = 5.66, P < 0.01). 54% of the OT (+) neurons in the PVN were FOS (+) in the carbachol treated fetuses, and only 8% of FOS (+) cells in the PVN were not OT-containing neurons.


Central cholinergic signal-mediated neuroendocrine regulation of vasopressin and oxytocin in ovine fetuses.

Shi L, Mao C, Zeng F, Zhang Y, Xu Z - BMC Dev. Biol. (2008)

FOS-ir and AVP-ir (or OT-ir) in the SON and PVN following i.c.v. carbachol. A: double labeling of FOS-ir and AVP-ir in the SON. B: double labeling of FOS-ir and OT-ir in the PVN. Solid arrows indicate co-localization of FOS-ir and AVP-ir (or OT-ir). Open arrows indicate AVP-ir (or OT-ir) positive cells without FOS-ir. Dash arrows indicate positive FOS-ir outside of AVP- (or OT-ir) containing cells. Scale bar = 10 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
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Figure 5: FOS-ir and AVP-ir (or OT-ir) in the SON and PVN following i.c.v. carbachol. A: double labeling of FOS-ir and AVP-ir in the SON. B: double labeling of FOS-ir and OT-ir in the PVN. Solid arrows indicate co-localization of FOS-ir and AVP-ir (or OT-ir). Open arrows indicate AVP-ir (or OT-ir) positive cells without FOS-ir. Dash arrows indicate positive FOS-ir outside of AVP- (or OT-ir) containing cells. Scale bar = 10 μm.
Mentions: Double labeling showed that there was no FOS-ir in AVP-containing and OT-containing cells in the brain of control fetuses. However, co-localization of FOS-ir in many AVP and OT neurons was detected in both sides of the SON and PVN following i.c.v. carbachol in the fetal hypothalamus (Figure 5). Although many AVP and OT neurons were co-localized with positive FOS-ir, there were some AVP and OT cells not labeled with FOS-ir. There was no difference in the total counting of AVP-ir and OT-ir in the SON and PVN between the control and the treated fetuses (all P > 0.05). Double labeling of FOS-ir and AVP-ir in the SON was significantly higher in the carbachol-treated fetuses than in the control animals (t = 6.78, P < 0.01). 82% of the AVP (+) neurons in the SON were FOS (+) in the carbachol treated fetuses. However, very few of FOS (+) cells in the SON (about 6%) were not AVP-containing neurons. Also, double labeling of FOS-ir and OT-ir in the PVN was significantly higher in the carbachol-treated fetuses than in the control animals (t = 5.66, P < 0.01). 54% of the OT (+) neurons in the PVN were FOS (+) in the carbachol treated fetuses, and only 8% of FOS (+) cells in the PVN were not OT-containing neurons.

Bottom Line: I.c.v. carbachol significantly increased fetal plasma AVP and OT concentrations.The results indicate that the central cholinergic mechanism is established and functional in the regulation of the hypothalamic neuropeptides during the final trimester of pregnancy.This provides evidence for a functional link between the development of central cholinergic mechanisms and hypothalamic neuropeptide systems in the fetus.

View Article: PubMed Central - HTML - PubMed

Affiliation: Perinatal Biology Center, Soochow University School of Medicine, Suzhou 215007, PR China. lshi@llu.edu

ABSTRACT

Background: The hypothalamic-neurohypophysial system plays a fundamental role in the maintenance of body fluid homeostasis by secreting arginine vasopressin (AVP) and oxytocin (OT) in response to a variety of signals, including osmotic and nonosmotic stimuli. It is well established that central cholinergic mechanisms are critical in the regulation of cardiovascular responses and maintenance of body fluid homeostasis in adults. Our recent study demonstrated that intracerebroventricular (i.c.v.) injection of carbachol elicited an increase of blood pressure in the near-term ovine fetuses. However, in utero development of brain cholinergic mechanisms in the regulation of the hypothalamic neuropeptides is largely unknown. This study investigated AVP and OT neural activation in the fetal hypothalamus induced by central carbachol.

Results: Chronically prepared near-term ovine fetuses (0.9 gestation) received an i.c.v. carbachol (3 microg/kg). Fetal blood samples were collected for AVP and OT assay, and brains were used for c-fos mapping studies. I.c.v. carbachol significantly increased fetal plasma AVP and OT concentrations. Intense FOS immunoreactivity (FOS-ir) was observed in the fetal supraoptic nuclei (SON) and paraventricular nuclei (PVN) in the hypothalamus. Double labeling demonstrated that a number of AVP- and OT-containing neurons in the fetal SON and PVN were expressing c-fos in response to central carbachol.

Conclusion: The results indicate that the central cholinergic mechanism is established and functional in the regulation of the hypothalamic neuropeptides during the final trimester of pregnancy. This provides evidence for a functional link between the development of central cholinergic mechanisms and hypothalamic neuropeptide systems in the fetus.

Show MeSH