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Cortical nNOS neurons co-express the NK1 receptor and are depolarized by Substance P in multiple mammalian species.

Dittrich L, Heiss JE, Warrier DR, Perez XA, Quik M, Kilduff TS - Front Neural Circuits (2012)

Bottom Line: These neurons are known to be GABAergic, to express Neuropeptide Y (NPY) and, in rats, to co-express the Substance P (SP) receptor NK1, suggesting a possible role for SP in sleep/wake regulation.Type I nNOS neurons co-expressed NK1 in all three species although the anatomical distribution within the cortex was species-specific.These results suggest a conserved role for SP in the regulation of cortical sleep-active neurons in mammals.

View Article: PubMed Central - PubMed

Affiliation: Biosciences Division, Center for Neuroscience, SRI International, Menlo Park CA, USA.

ABSTRACT
We have previously demonstrated that Type I neuronal nitric oxide synthase (nNOS)-expressing neurons are sleep-active in the cortex of mice, rats, and hamsters. These neurons are known to be GABAergic, to express Neuropeptide Y (NPY) and, in rats, to co-express the Substance P (SP) receptor NK1, suggesting a possible role for SP in sleep/wake regulation. To evaluate the degree of co-expression of nNOS and NK1 in the cortex among mammals, we used double immunofluorescence for nNOS and NK1 and determined the anatomical distribution in mouse, rat, and squirrel monkey cortex. Type I nNOS neurons co-expressed NK1 in all three species although the anatomical distribution within the cortex was species-specific. We then performed in vitro patch clamp recordings in cortical neurons in mouse and rat slices using the SP conjugate tetramethylrhodamine-SP (TMR-SP) to identify NK1-expressing cells and evaluated the effects of SP on these neurons. Bath application of SP (0.03-1 μM) resulted in a sustained increase in firing rate of these neurons; depolarization persisted in the presence of tetrodotoxin. These results suggest a conserved role for SP in the regulation of cortical sleep-active neurons in mammals.

No MeSH data available.


Related in: MedlinePlus

SP depolarizes cortical NK1+ neurons. (A) Application of 50 nM SP to the bath depolarizes an NK1+ neuron in the mouse cortex and generates an increase in firing rate that persists for about 10 min. (B) Successive applications of 50 nM SP elicit similar responses during blockade of voltage-dependent Na+ channels with TTX. (C) SP increases the firing rate of cortical NK1+ neurons in the rat. (D) Under TTX blockade, rat NK1+ cortical neurons can be depolarized for a prolonged period despite the short duration of SP bath application.
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Figure 4: SP depolarizes cortical NK1+ neurons. (A) Application of 50 nM SP to the bath depolarizes an NK1+ neuron in the mouse cortex and generates an increase in firing rate that persists for about 10 min. (B) Successive applications of 50 nM SP elicit similar responses during blockade of voltage-dependent Na+ channels with TTX. (C) SP increases the firing rate of cortical NK1+ neurons in the rat. (D) Under TTX blockade, rat NK1+ cortical neurons can be depolarized for a prolonged period despite the short duration of SP bath application.

Mentions: To evaluate the effect of SP on neuronal firing rate, mouse cortical neurons were initially hyperpolarized with 0–10 pA to reduce spontaneous firing. Application of 0.03–1 μM SP induced on average (all values correspond to mean ± standard deviation) an increase in firing rate of 10.2 ± 4.9 spikes/s (N = 11). Blockade of voltage-dependent sodium channels by >5 min of bath application of 1 μM TTX was tested in seven cells. Addition of 0.03–0.3 μM SP induced a depolarization of 11.9 ± 4.6 mV (N = 7). SP-induced depolarization in the presence of TTX was found in all cells tested, indicating that the action of SP is most likely direct. Figure 4A shows an example of SP-induced depolarization of a neuron in mouse cortex. Figure 4B shows the membrane potential of a different neuron under TTX and its response to two successive applications of SP. The large variability observed in both the amplitude and the duration of the SP-induced depolarization for a given SP concentration precludes the elaboration of a dose response curve at the present time. Similar results were obtained for TMR-SP fluorescent neurons selected for recording in rat cortical slices, where bath application of 0.1–0.3 μM SP induced an increase of 5 ± 2 spikes/s (N = 9) in firing rate and, under 1 μM TTX, a depolarization of 8.1 ± 3.6 mV (N = 5 out of 5 neurons tested). Figure 4C shows an example of an SP-induced increase in firing rate of a TMR-SP-responsive cell in a rat cortical slice. Figure 4D shows a different neuron exhibiting a prolonged depolarization after 1 min application of SP.


Cortical nNOS neurons co-express the NK1 receptor and are depolarized by Substance P in multiple mammalian species.

Dittrich L, Heiss JE, Warrier DR, Perez XA, Quik M, Kilduff TS - Front Neural Circuits (2012)

SP depolarizes cortical NK1+ neurons. (A) Application of 50 nM SP to the bath depolarizes an NK1+ neuron in the mouse cortex and generates an increase in firing rate that persists for about 10 min. (B) Successive applications of 50 nM SP elicit similar responses during blockade of voltage-dependent Na+ channels with TTX. (C) SP increases the firing rate of cortical NK1+ neurons in the rat. (D) Under TTX blockade, rat NK1+ cortical neurons can be depolarized for a prolonged period despite the short duration of SP bath application.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3367498&req=5

Figure 4: SP depolarizes cortical NK1+ neurons. (A) Application of 50 nM SP to the bath depolarizes an NK1+ neuron in the mouse cortex and generates an increase in firing rate that persists for about 10 min. (B) Successive applications of 50 nM SP elicit similar responses during blockade of voltage-dependent Na+ channels with TTX. (C) SP increases the firing rate of cortical NK1+ neurons in the rat. (D) Under TTX blockade, rat NK1+ cortical neurons can be depolarized for a prolonged period despite the short duration of SP bath application.
Mentions: To evaluate the effect of SP on neuronal firing rate, mouse cortical neurons were initially hyperpolarized with 0–10 pA to reduce spontaneous firing. Application of 0.03–1 μM SP induced on average (all values correspond to mean ± standard deviation) an increase in firing rate of 10.2 ± 4.9 spikes/s (N = 11). Blockade of voltage-dependent sodium channels by >5 min of bath application of 1 μM TTX was tested in seven cells. Addition of 0.03–0.3 μM SP induced a depolarization of 11.9 ± 4.6 mV (N = 7). SP-induced depolarization in the presence of TTX was found in all cells tested, indicating that the action of SP is most likely direct. Figure 4A shows an example of SP-induced depolarization of a neuron in mouse cortex. Figure 4B shows the membrane potential of a different neuron under TTX and its response to two successive applications of SP. The large variability observed in both the amplitude and the duration of the SP-induced depolarization for a given SP concentration precludes the elaboration of a dose response curve at the present time. Similar results were obtained for TMR-SP fluorescent neurons selected for recording in rat cortical slices, where bath application of 0.1–0.3 μM SP induced an increase of 5 ± 2 spikes/s (N = 9) in firing rate and, under 1 μM TTX, a depolarization of 8.1 ± 3.6 mV (N = 5 out of 5 neurons tested). Figure 4C shows an example of an SP-induced increase in firing rate of a TMR-SP-responsive cell in a rat cortical slice. Figure 4D shows a different neuron exhibiting a prolonged depolarization after 1 min application of SP.

Bottom Line: These neurons are known to be GABAergic, to express Neuropeptide Y (NPY) and, in rats, to co-express the Substance P (SP) receptor NK1, suggesting a possible role for SP in sleep/wake regulation.Type I nNOS neurons co-expressed NK1 in all three species although the anatomical distribution within the cortex was species-specific.These results suggest a conserved role for SP in the regulation of cortical sleep-active neurons in mammals.

View Article: PubMed Central - PubMed

Affiliation: Biosciences Division, Center for Neuroscience, SRI International, Menlo Park CA, USA.

ABSTRACT
We have previously demonstrated that Type I neuronal nitric oxide synthase (nNOS)-expressing neurons are sleep-active in the cortex of mice, rats, and hamsters. These neurons are known to be GABAergic, to express Neuropeptide Y (NPY) and, in rats, to co-express the Substance P (SP) receptor NK1, suggesting a possible role for SP in sleep/wake regulation. To evaluate the degree of co-expression of nNOS and NK1 in the cortex among mammals, we used double immunofluorescence for nNOS and NK1 and determined the anatomical distribution in mouse, rat, and squirrel monkey cortex. Type I nNOS neurons co-expressed NK1 in all three species although the anatomical distribution within the cortex was species-specific. We then performed in vitro patch clamp recordings in cortical neurons in mouse and rat slices using the SP conjugate tetramethylrhodamine-SP (TMR-SP) to identify NK1-expressing cells and evaluated the effects of SP on these neurons. Bath application of SP (0.03-1 μM) resulted in a sustained increase in firing rate of these neurons; depolarization persisted in the presence of tetrodotoxin. These results suggest a conserved role for SP in the regulation of cortical sleep-active neurons in mammals.

No MeSH data available.


Related in: MedlinePlus