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Co-existence of NADPH-diaphorase, fibroblast growth factor-2 and fibroblast growth factor receptor in spinal
C Stapf1, M Shakibaei, D Blottner
1Institute for Anatomy, Freie Universität Berlin, Berlin, Germany.
Abstract:
In the rat spinal cord, we found substantial co-existence of fibroblast growth factor-2, fibroblast growth factor receptor (type-1 or flg) immunoreactivity and reduced nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase activity (a histochemical marker for neuronal nitric oxide synthase) in preganglionic autonomic cell groups of intermediate layers VI, VII and X. Anti-fibroblast growth factor-2 and anti-nitric oxide synthase binding sites were confined to the cytoplasm of reactive neurons as judged by immunogold electron microscopy. Within the major autonomic nucleus, i.e. intermediolateral column, three different populations were identified: (i) fibroblast growth factor and fibroblast growth factor receptor, (ii) fibroblast growth factor/NADPH-diaphorase and (iii) NADPH-diaphorase-only stained cell groups. Sympathoadrenal neurons were prelabelled with fluorescent tracer Fast Blue and co-stained for fibroblast growth factor-like protein and NADPH-diaphorase, suggesting heterologous diversification of neuronal phenotypes and functional organization in the spinal autonomic system. Our findings suggest intriguing roles for nitric oxide and fibroblast growth factor-2 cytokine in the preganglionic sympathetic spinal cord system: The "short-term" diffusible messenger nitric oxide may act as "tonic" and/or "phasic" signal within rostrocaudally oriented function-specific preganglionic units necessary for integrated target control. The "long-term" messenger fibroblast growth factor-2 may be involved in, for example, cytokine-dependent regulation of neuronal NADPH-diaphorase/nitric oxide synthase. Furthermore, co-existence of NADPH-diaphorase, fibroblast growth factor-2 and receptor in sympathoadrenal neurons suggest mutual target-specific regulatory functions, e.g. hormone release and blood perfusion or maintenance of phenotype and plasticity responsiveness of adrenal medullary tissue.
Insights
This study reveals that fibroblast growth factor-2 (FGF-2) and nitric oxide synthase (NOS) coexist in rat spinal cord autonomic neurons, suggesting roles in regulating sympathetic functions and adrenal medullary tissue. These findings highlight FGF-2 and NOS in spinal autonomic system organization.
Area of Science:
- Neuroscience
- Cell Biology
- Molecular Biology
Background:
- The spinal autonomic system regulates vital functions.
- Neuronal nitric oxide synthase (nNOS) and fibroblast growth factor-2 (FGF-2) are implicated in neuronal signaling.
- Understanding their co-expression and roles in preganglionic sympathetic neurons is crucial.
Purpose of the Study:
- To investigate the co-localization of FGF-2 and nNOS in rat spinal cord preganglionic autonomic neurons.
- To explore the functional implications of this co-expression in the spinal autonomic system.
Main Methods:
- Immunohistochemistry and immunogold electron microscopy were used to detect FGF-2 and nNOS.
- Histochemical staining for NADPH-diaphorase activity (a marker for nNOS) was performed.
- Fluorescent tracer techniques were employed to identify specific neuronal populations, including sympathoadrenal neurons.
Main Results:
- Substantial co-existence of FGF-2 immunoreactivity and NADPH-diaphorase activity was found in rat spinal cord autonomic cell groups (layers VI, VII, X).
- Three distinct neuronal populations were identified in the intermediolateral column based on FGF-2 and NADPH-diaphorase staining.
- Sympathoadrenal neurons showed co-expression of FGF-2 and NADPH-diaphorase, indicating phenotypic diversification.
Conclusions:
- Nitric oxide (NO) and FGF-2 play significant roles in the preganglionic sympathetic spinal cord system.
- NO may function as a short-term signal for integrated target control, while FGF-2 might regulate nNOS expression.
- Co-expression suggests mutual regulatory functions in sympathoadrenal neurons, impacting hormone release, blood perfusion, and adrenal tissue plasticity.