Journal of chemical neuroanatomy
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J. Chem. Neuroanat. · Jun 2006
The role of phosphodiesterase isoforms 2, 5, and 9 in the regulation of NO-dependent and NO-independent cGMP production in the rat cervical spinal cord.
NO-responsive, cGMP-producing structures are abundantly present in the cervical spinal cord. NO-mediated cGMP synthesis has been implicated in nociceptive signaling and it has been demonstrated that cGMP has a role establishing synaptic connections in the spinal cord during development. As cGMP levels are controlled by the activity of soluble guanylyl cyclase (synthesis) and the phosphodiesterase (PDE) activity (breakdown), we studied the influence of PDE activity on NO-stimulated cGMP levels in the rat cervical spinal cord. cGMP-immunoreactivity (cGMP-IR) was localized in sections prepared from slices incubated in vitro. ⋯ Incubation of the slices in the presence of IBMX, DEANO in combination with BAY 41-2272, a NO-independent activator of soluble guanylyl cyclase, provided evidence for endogenous NO synthesis in the slice preparations and enhanced cGMP-IR in all lamina. Under these conditions cGMP-IR colocalized with substance P in a subpopulation of substance P-IR fibers. It is concluded that NO functions as a retrograde neurotransmitter in the spinal cord but that also postsynaptic structures are NO-responsive by producing cGMP. cGMP-IR in a subpopulation of isolectin B4 positive fibers and boutons is indicative for a role of NO-cGMP signaling in nociceptive processing. cGMP levels in the spinal cord are controlled by the concerted action of a number of PDE isoforms, which can be present in the same cell.
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J. Chem. Neuroanat. · Jul 2012
VGF peptides upon osmotic stimuli: changes in neuroendocrine regulatory peptides 1 and 2 in the hypothalamic-pituitary-axis and plasma.
VGF or VGF nerve growth factor inducible is a protein that has been found to play a role in regulating energy homeostasis and metabolism. From VGF precursor derive two neuroendocrine regulatory peptides NERP-1 and NERP-2 that, intracerebroventricular (icv) injected, modulate the antidiuretic hormone (ADH) release. Thus, we investigated possible modulations of the NERPs and other VGF peptides (namely VGF C-terminus, TLQP and PGH) in the hypothalamic-pituitary-axis, adrenal gland and plasma upon osmotic stimuli. ⋯ By immunohistochemistry, the VGF peptides studied (apart from the TLQP peptides) were present in the hypothalamic and pituitary ADH containing neurons of the control rats, while using WD and SL rats, an immunostaining increase was selectively revealed for VGF C-terminus peptides in the hypothalamic neurons that produce ADH. All VGF changes found using SL rats disappeared after only 1h of rehydration. In conclusion, we hypothesize that NERPs may be involved in both autocrine and endocrine mechanisms important for the fluid balance.
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J. Chem. Neuroanat. · Dec 2006
Projections from the mesopontine tegmental anesthesia area to regions involved in pain modulation.
Pentobarbital microinjected into a restricted locus in the upper brainstem induces a general anesthesia-like state characterized by atonia, loss of consciousness, and pain suppression as assessed by loss of nocifensive response to noxious stimuli. This locus is the mesopontine tegmental anesthesia area (MPTA). Although anesthetic agents directly influence spinal cord nociceptive processing, antinociception during intracerebral microinjection indicates that they can also act supraspinally. ⋯ The MPTA also has modest direct projections to the trigeminal nuclear complex and to superficial layers of the dorsal horn. Double anterograde and retrograde labeling at the light and electron microscopic levels shows that MPTA neurons with descending projections synapse directly on spinally projecting cells of rostromedial medulla. The prominence of the MPTA's projection to the rostromedial medulla suggests that, like the PAG, it may exert antinociceptive actions via this bulbospinal relay.
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J. Chem. Neuroanat. · Mar 2001
Nitric oxide synthase neurons in the rodent spinal cord: distribution, relation to Substance P fibers, and effects of dorsal rhizotomy.
The indirect immunofluorescent method was employed to investigate the distribution of neuronal nitric oxide synthase-like immunoreactivity(nNOS-LI) in the spinal cord of the golden hamster and to compare it to data obtained from rats. Immunoreactive neurons were found throughout the cervico-sacral extent in the dorsal horn (mainly in laminae I-III) and in the preganglionic autonomic regions, i.e., the sympathetic intermediolateral nucleus (IML), lateral funicle (LF), intercalated region (IC), the area surrounding the central canal (CA), and the sacral preganglionic parasympathetic cell group. While the distribution of immunoreactive cells was generally similar in both species, some differences were observed. ⋯ Numbers of nNOS-LI cell bodies in the autonomic regions were not altered following dorsal root transection. The present study provides data on the widespread distribution of nNOS in the spinal cord of golden hamster and describes the partial coincidence of the enzyme in PSN. The effects of dorsal rhizotomy on nNOS-LI neurons in the dorsal horn reveal that primary-afferent fibers provide a stimulatory influence on neurons of the dorsal horn to generate the gaseous neuroactive substance, nitric oxide.
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J. Chem. Neuroanat. · Apr 2011
Evidence for cellular injury in the midbrain of rats following chronic constriction injury of the sciatic nerve.
Complex behavioural disabilities, as well as pain, characterise neuropathic pain conditions for which clinical treatment is sought. In rats, chronic constriction injury (CCI) of the sciatic nerve evokes, allodynia and hyperalgesia as well as three distinct patterns of disability, characterised by changes in social and sleep-wake behaviours: (i) Pain & Disability; (ii) Pain & Transient Disability and (iii) Pain alone. Importantly, the degree of allodynia and hyperalgesia is identical for each of these groups. ⋯ The anatomical location of TUNEL and cleaved-caspase-3 immunoreactive profiles in the midbrain was also identified. Rats with Pain & Disability showed: (i) pro-apoptotic ratios of Bax:Bcl-2 mRNAs; (ii) decreased HSP60 mRNA; (iii) increased iNOS and MEK2 mRNAs; (iv) TUNEL-positive profiles in the lateral and ventrolateral PAG; and (v) caspase-3 immunoreactive neurons in the mesencephalic nucleus of the trigeminal nerve. Cell death in these specific midbrain regions may underlie the disabilities characterising this subgroup of nerve-injured rats.