Nitric oxide synthase-containing projections to the ventrobasal thalamus in the rat

Usunoff, Kamen G.; Kharazia, Viktor; Valtschanoff, Juli G.; Schmidt, Harald; Weinberg, Richard J.

doi:10.1007/s004290050278

Cited by 34 publications

(27 citation statements)

References 111 publications

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“…An ipsilateral spinothalamic tract was reported in the rat (Burstein et al 1990;Usunoff et al 1999), and clinical observations indicate that ipsilaterally projecting spinothalamic neurons exist also in humans (reviewed by Nathan et al 2001). In the rat, the ipsilateral spinothalamic projection is significant: according to Burstein et al (1990), the ipsilaterally projecting cells are approximately 10% of the total spinothalamic neuronal population.…”

Section: Discussionmentioning

confidence: 99%

Neurons in the dorsal column nuclei of the rat emit a moderate projection to the ipsilateral ventrobasal thalamus

et al. 2005

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The dorsal column nuclei (DCN; gracile and cuneate nuclei) give rise to the medial lemniscus, the fibre system that provides an organised somatosensory input to the thalamus. Unlike the spinothalamic and trigeminothalamic tracts that project, also to the ipsilateral thalamus, the medial lemniscus system is believed to be entirely crossed. We demonstrate that DCN emit a small number of axons that reach the ipsilateral thalamus. As retrograde fluorescent neuronal tracer Fluoro-gold was stereotaxically injected in the ventrobasal thalamus of nine young adult Wistar rats. The injection foci were voluminous and encroached upon adjacent nuclei, but the periphery of the injection halo never spilled over to the contralateral thalamus. All sections of the contralateral gracile and cuneate nuclei and the midline nucleus of Bischoff contained abundant retrogradely labelled neurons. The comparison with the Nissl-stained parallel sections suggests that approximately 70-80% of the DCN neurons project to the contralateral thalamus. Counting of retrogradely labelled neurons in two cases revealed 4,809 and 4,222 neurons in the contralateral and 265 and 214 in the ipsilateral DCN, respectively. Thus, although less prominent than the ipsilateral spinothalamic tract, the lemniscal system also emits an ipsilateral projection that accounts for about 5% of the neuronal population in DCN that innervates the ventrobasal thalamus.

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Section: Discussionmentioning

confidence: 99%

Neurons in the dorsal column nuclei of the rat emit a moderate projection to the ipsilateral ventrobasal thalamus

et al. 2005

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“…Previous investigations have, however, addressed the coexistence of NOS and Ach within the brainstem parabrachial region. Usunoff et al (1999) reported that ϳ25% of rat LDT/pedunculopontine tegmental (PPN) projection neurons which target VB stain positively for NADPHd. A similar percentage of parabrachial (LDT/PPN) neurons was found to also co-contain Ach and project to the dorsal lateral geniculate nucleus in feline (Bickford et al, 1993).…”

Section: Differential Expression Of Nos and 5ht In Subcortical Dr Promentioning

confidence: 99%

Differential expression of nitric oxide in serotonergic projection neurons: Neurochemical identification of dorsal raphe inputs to rodent trigeminal somatosensory targets

Simpson

Waterhouse

Lin

2003

J of Comparative Neurology

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The dorsal raphe (DR) is invested with nitric oxide synthase (NOS)-expressing profiles. To characterize the connections of NO-containing cells and further assess neurochemical relationships maintained by DR, the transmitter identity of the raphe projection to the trigeminal somatosensory system was examined. Rats were injected with retrograde tracer into vibrissae-related target areas or with anterograde tracer into DR. NADPH-diaphorase (NADPHd) histochemistry or NOS-immunostaining was combined with serotonin (5HT)- or serotonin transporter (SERT)-immunolabeling to examine: 1) the presence of NO in 5HT-containing axons from DR; 2) the distribution of NO-containing fibers with respect to other nitrergic profiles in the somatosensory system; and 3) the propensity for individual projection neurons in specific subdivisions of DR to colocalize 5HT and NO. Results confirm that "barrel-like" patches can be identified in several adult trigeminal relay nuclei by NADPHd histochemistry and demonstrate that fibers from DR contain 5HT and NO. Observations include a high percentage of cortical midline projection neurons which contained NADPHd (70-80%) and coexpressed 5HT. In contrast, approximately 40% of retrogradely labeled DR-thalamus cells in the lateral wing demonstrated NADPHd or 5HT expression, but not both in the same neuron. Colocalization of NADPHd and 5HT within individual DR projection neurons indicates that: i) DR is a source of nitrergic input to trigeminal structures, and ii) NO and 5HT may be simultaneously released to influence information-processing within somatosensory targets. Disparities in NADPHd expression between retrogradely labeled DR neuronal subpopulations further suggest functional differences in the impact of NO on cortical and subcortical targets.

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“…16 and 19). In VP and the somatosensory part of the RTN, the number of similar terminals originating from brainstem fibers is extremely small, and they use transmitters other than glutamate (20,21).…”

Section: Differences In Number Of Glur4 Subunits At Corticothalamic Smentioning

confidence: 99%

Differences in quantal amplitude reflect GluR4- subunit number at corticothalamic synapses on two populations of thalamic neurons

Golshani

Liu

Jones

2001

Proc. Natl. Acad. Sci. U.S.A.

211

151

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Low-frequency thalamocortical oscillations that underlie drowsiness and slow-wave sleep depend on rhythmic inhibition of relay cells by neurons in the reticular nucleus (RTN) under the influence of corticothalamic fibers that branch to innervate RTN neurons and relay neurons. To generate oscillations, input to RTN predictably should be stronger so disynaptic inhibition of relay cells overcomes direct corticothalamic excitation. Amplitudes of excitatory postsynaptic conductances (EPSCs) evoked in RTN neurons by minimal stimulation of corticothalamic fibers were 2.4 times larger than in relay neurons, and quantal size of RTN EPSCs was 2.6 times greater. GluR4-receptor subunits labeled at corticothalamic synapses on RTN neurons outnumbered those on relay cells by 3.7 times, providing a basis for differences in synaptic strength. reticular nucleus ͉ ventral posterior nucleus ͉ dual whole-cell recordings ͉ minimal stimulation ͉ synaptic strength C orticothalamic fibers that arise from layer VI cells in the cerebral cortex branch to innervate neurons in the reticular nucleus (RTN) and thalamocortical relay neurons in the underlying thalamus (1, 2) are a powerful influence in the generation of neuronal synchrony in thalamus and cortex (3). In RTN and relay nuclei, they end in excitatory synapses associated with ␣-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), N-methyl-D-aspartate, and metabotropic glutamate receptors (4-8). Corticothalamic fibers strongly excite inhibitory neurons of the RTN and these in turn inhibit relay neurons. Relay neurons fire bursts of action potentials as they recover from inhibition, re-exciting RTN cells so that the sequence continues (9-11). The capacity of the disynaptic RTN-generated inhibitory postsynaptic potential (IPSP) to overcome the monosynaptic excitatory postsynaptic potential (EPSP) generated by the direct corticothalamic input to the relay neurons is a key element in generation of low-frequency oscillations or spindle waves (10, 12), which are the electroencephalographic hallmarks of drowsiness and early stages of slow-wave sleep. In models in which the strength of corticothalamic input to RTN neurons is set equal to that to relay neurons, the disynaptic IPSP is shunted by the monosynaptic EPSP, and the network does not oscillate (13). Here, we demonstrate that excitatory postsynaptic conductances (EPSCs) elicited by minimal stimulation of corticothalamic fibers are stronger quantitatively in RTN than in ventral posterior thalamic nucleus (VP) neurons, and that the number of GluR4 subunits at corticothalamic synapses on RTN neurons is correspondingly greater than at synapses on relay cells, providing a basis for synaptic heterogeneity. Materials and MethodsWhole-cell recordings were made at 22-25°C from neurons in layer VI of somatosensory cortex, RTN, and VP in brain slices from postnatal day 13 to 24 ICR mice, cut at an angle that preserves corticothalamic and thalamocortical connectivity, and maintained in vitro as described (14). Electrode resistances were 2-5 M...

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Nitric oxide synthase-containing projections to the ventrobasal thalamus in the rat

Cited by 34 publications

References 111 publications

Neurons in the dorsal column nuclei of the rat emit a moderate projection to the ipsilateral ventrobasal thalamus

Neurons in the dorsal column nuclei of the rat emit a moderate projection to the ipsilateral ventrobasal thalamus

Differential expression of nitric oxide in serotonergic projection neurons: Neurochemical identification of dorsal raphe inputs to rodent trigeminal somatosensory targets

Differences in quantal amplitude reflect GluR4- subunit number at corticothalamic synapses on two populations of thalamic neurons

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