Renal Nerves and Blood Pressure

Role of Calcitonin gene-related peptide (CGRP)

CGRP is a potent vasodilator so it is not surprising our CGRP Antibody was used in this study. Custódio AH, de Lima MC, Vaccari B, Boer PA, Gontijo JAR (2017) Renal sodium handling and blood pressure changes in gestational protein-restricted offspring: Role of renal nerves and ganglia neurokinin expression. PLoS ONE 12(6): e0179499. https://doi.org/10.1371/journal.pone.0179499

Figure. Comparative expression of SP and CGRP in the renal pelvis of 16-week-old rats. The pictures show a normal distribution of these neurokinins in NP (A and D). In LP offspring, no difference was observed in SP immunoreactivity (A, B, and C), but CGRP immunoreactivity was significantly more intense in NP (D, E, and F) compared with age-matched LP offspring.

We are always honored when our solutions are referenced in publications and will continue to post new findings here.

Epidermal Nerve Fibers in Neuropathic Pain Model

Re-innervation in spared nerve injury (SNI) vs normal rats
Neuromics' Pain and Inflammation Research Antibodies are frequently used to help researchers find root causes of neuropathic pain. This is a fascinating study of re-innervation patterns of epidermal and dermal nerve fibers in a rat neuropathic pain model (Note: our Guinea Pig Polyclonal P2X3 Antibody was used in this study): Liron S. Durakua, Mehdi Hossaini, Barthold N. Schüttenhelm, b, Joan C. Holstege, Martijn Baas, Tom J.H. Ruigrok, Erik T. Walbeehm. Re-innervation patterns by peptidergic Substance-P, non-peptidergic P2X3, and myelinated NF-200 nerve fibers in epidermis and dermis of rats with neuropathic pain. Experimental Neurology Volume 241, March 2013, Pages 13–24. doi.org/10.1016/j.expneurol.2012.11.029.

Non-footpad area vs. footpad.The distribution pattern between the center non-footpad area and footpad is compared for the different subgroups of sensory skin fibers. For epidermal Sub P-IR and upper dermal NF-200-IR fibers there is an equal density of fibers in the center and footpad area suggesting a homogenous distribution over the foot sole of a rat. Whereas for epidermal P2X3-IR fibers there is a significant lower number of P2X3-IR fibers in the footpads as compared to the center non-footpad area, suggesting a heterogeneous distribution in the foot sole for this type of sensory fibers. N = 5 per group. Unpaired t-test. ***: p < 0,001. Scale bar: 250 μm. doi.org/10.1016/j.expneurol.2012.11.029

Illustration of the skin innervation in normal and SNI situation.Illustration showing the innervation pattern of subgroups of sensory skin fibers in the normal situation and in the SNI model 10 weeks PO. In the naïve animals the peptidergic CGRP and non-peptidergic P2X3 fibers have a lower density in the footpads as compared to the non-footpad areas, while the Substance P and NF-200 fibers have an equal distribution over the complete foot sole. In the SNI model there is a significant increase of CGRP epidermal fibers in the medial and lateral area of the foot sole and there is a complete re-innervation of the center area. In addition the footpads in the SNI model are hyper-innervated with CGRP fibers. Substance P and P2X3 and NF-200 fibers show no increased density in the uninjured medial and lateral area after 10 weeks PO. In addition, Substance P and P2X3 fibers hardly re-innervate the center area; however, the NF-200 fibers have the same density of fibers in the denervated area as in the normal situation. In the SNI model the medial, center and lateral area have all an increase in LC's, with the center area being the most prominent one. In addition the epidermis thickness of the SNI model has decreased significantly in all the three areas after 10 weeks PO.
Related Postings: http://neuromics.blogspot.com/search/label/Neuropathic%20Pain.

P2X3 Receptor and CGRP Antibodies Immunostaining

Dr. Alfredo Ribeiro-da-Silva, McGill University, is a serial publisher of studies using our pain and inflammation research antibodies.

Here, use of our rabbit anti-CGRP and guinea pig anti-P2X3 is referenced. Please note the high titer of these antibodies (dilution is 1:25,000): Abeer W Saeed, Alfredo Ribeiro-da-Silva. Non-peptidergic primary afferents are presynaptic to neurokinin-1 receptor immunoreactive lamina I projection neurons in rat spinal cord. Molecular Pain 2012, 8:64 doi:10.1186/1744-8069-8-64.

Images: CGRP, IB4 and P2X3 staining in transverse spinal cord sections. A and B show low magnification confocal images of CGRP-IR and IB4 positive (A) or P2X3-IR (B) fibers. C and D represent high magnification confocal images from the middle third of the lateromedial extent of the superficial dorsal horn. In C, note that there is limited co-localization of IB4 and CGRP (in yellow). Arrowheads show axonal varicosities (boutons) from nonpeptidergic fibers in lamina I, which do not co-localize CGRP immunoreactivity. The framed regions in A and B indicate the approximate regions from where C and D, respectively, were obtained (the latter originate from other sections). CGRP (in green); IB4 (in red); P2X3 (in red). Scale bar (A, B) = 200 μm; scale bar (C, D) = 20 μm

Tissue processing: The injection site at the level of the parabrachial nucleus was examined by cutting serial, 100 μm-thick coronal sections of the relevant brain region. The dorsal aspect of the L4-L5 spinal cord segment was cut into serial, 50 μm-thick horizontal sections (n = 10), 50 μm-thick parasagittal sections (n = 4) or 50 μm-thick transverse sections (n = 4). All sections were cut using a freezing sledge microtome (Leica, Richmond Hill, Ontario) and collected as freefloating in phosphate-buffered saline (PBS) with 0.2% Triton-X 100 (PBS + T). To block unspecific staining, all spinal cord sections were incubated, for one hour, in 10% normal donkey serum (NDS) (Jackson, West Grove, PA) in PBS + T at room temperature. Subsequently, the sections were placed in primary antibodies (or conjugated lectin IB4 - see below) for 48 hours at 4 °C. We used a mixture of 2 or 4 primary antibodies (each raised in a different species), or IB4, in PBS + T containing 5% NDS. Next, the sections were washed in PBS + T and then incubated in species-specific secondary antibodies that were raised in donkey and conjugated to either AlexaFluor 488, AlexaFluor 405, Rhodamine RedX or biotin. The sections were incubated in 3 different cocktails: #1) rabbit anti-CGRP at a 1:200 dilution (Sigma, St Louis, MO) and lectin IB4 conjugated to AlexaFluor 568 at a 1:200 dilution (Molecular Probes); #2) rabbit anti-CGRP and guinea pig anti-P2X3 at a 1:25,000 dilution (Neuromics, Edina, MN); #3) goat anti-CTb at a 1:5000 dilution (List Biological), rabbit anti-NK-1r at a 1:10000 dilution (Sigma, St Louis, MO), guinea pig anti-CGRP at a 1:8000 dilution (Peninsula, San Carlos, CA) and lectin IB4 conjugated to AlexaFluor 647 at a 1:200 dilution (Molecular Probes). All the sections were washed with PBS + T and then (for #1) incubated for 2 hours at room temperature with donkey anti-rabbit AlexaFluor 488; (for #2) incubated for 90 minutes in a biotin conjugated donkey anti-guinea pig IgG (Jackson Immunoresearch, West Grove, PA, 1:200). Further signal amplification was achieved by treating the sections with 1 hour incubation in an avidin-biotin (A + B) complex (Vectastain Elite ABC kit, Vector Laboratories) followed by tyramide (Perkin-Elmer, Norwalk, CT, 1:75) for 7 minutes. Sections were then incubated in streptavidin conjugated to AlexaFluor 568 (Molecular Probes, Eugene, OR, 1:200) and donkey anti-rabbit AlexaFluor 488; or (for #3) incubated for 2 hours at room temperature with secondary antibodies: donkey anti-goat Rhodamine Red X, donkey anti-rabbit AlexaFluor 488, and donkey anti-guinea pig AlexaFluor 405. Finally, sections were washed with PBS, mounted on gelatin-subbed slides and coverslipped with an anti-fading mounting medium (Aqua Polymount; Polysciences, Warrington, PA). Slides were stored at −4 °C pending further processing.

I will continue to publish outstanding customer data/images using our natibodies/markers.

TLR3s and the Synaptic Transmission of Itch

Synaptic Transmission Markers Trifecta

Itch, also known as pruritus, is a common, intractable symptom of several skin diseases, such as atopic dermatitis and xerosis. This chronic condition erodes quality of life.

The authors of this publication have made an important discovery that could prove a target for treating chronic itch. They also used 3 of our markers to confirm this discovery-guinea pig anti-TRPV1, guinea pig anti-SP antibody and rabbit anti-CGRP antibodies: Tong Liu, Temugin Berta, Zhen-Zhong Xu,Chul-Kyu and Ru-Rong Ji. TLR3 deficiency impairs spinal cord synaptic transmission, central sensitization, and pruritus in mice. J Clin Invest. 2012 June 1; 122(6): 2195–2207. Published online 2012 May 8. doi:10.1172/JCI45414.

Highlights: Scratching behaviors induced by histamine-dependent and -independent pruritogens are markedly reduced in mice lacking the Tlr3 gene. TLR3 is expressed mainly by small-sized primary sensory neurons in dorsal root ganglions (DRGs) that coexpress the itch signaling pathway components transient receptor potential subtype V1 and gastrin-releasing peptide. Ttreatment with a TLR3 agonist induces inward currents and action potentials in DRG neurons and elicited scratching in WT mice but not Tlr3–/– mice. Furthermore, excitatory synaptic transmission in spinal cord slices and long-term potentiation in the intact spinal cord were impaired in Tlr3–/– mice but not Tlr7–/– mice. Consequently, central sensitization–driven pain hypersensitivity, but not acute pain, was impaired in Tlr3–/– mice. In addition, TLR3 knockdown in DRGs also attenuated pruritus in WT mice. Finally, chronic itch in a dry skin condition was substantially reduced in Tlr3–/– mice. This demonstrates a critical role of TLR3 in regulating sensory neuronal excitability, spinal cord synaptic transmission, and central sensitization.

Images: Impaired scratching behaviors and reduced c-Fos expression in the spinal cords in Tlr3–/– mice. (A and B) Scratches in every 5 minutes (left) and 0–30 minutes (right) induced by intradermal injection of 50 μl compound 48/80 (100 μg) and CQ (200 μg). Note a reduction of both histaminergic (compound 48/80) and nonhistaminergic (CQ) itch in Tlr3–/– mice. *P < 0.05, Student’s t test; n = 11–13 mice for each group. Mean ± SEM. Two-way repeated-measures ANOVA analysis also shows a significant difference in the time course of compound 48/80– and CQ-induced scratching between the 2 groups (P < 0.05). (C) c-Fos–like immunoreactivity in the dorsal horn of the cervical spinal cord in WT and Tlr3–/– mice 2 hours after intradermal injection of compound 48/80 (48/80) or CQ. Right panels show the number of c-Fos–positive neurons in the dorsal horn. Scale bars, 100 μm. *P < 0.05, Student’s t test; n = 4–6 mice. All the data are mean ± SEM.

Images: Expression of TLR3 in a subset of small-sized DRG neurons. (A) Single-cell RT-PCR analysis from dissociated small-sized DRG neurons showing the distinct and overlapped distribution patterns of TLR3 and TLR7 in DRG neurons. The lanes were run on the same gel but were noncontiguous. M, marker; NC, negative control. (B) Single-cell RT-PCR analysis from dissociated small-sized DRG neurons showing colocalization of TLR3 with TPRV1 and GRP. Similar results were obtained from 3 independent experiments in 30 cells collected from different animals. (C) Double immunostaining in DRGs showing co-colocalization of TLR3 and GRP. Red and yellow arrows indicate GRP+ only and double-labeled neurons, respectively. Scale bars: 50 μm. (D) Cell size distribution frequency of TLR3+ and GRP+ neurons. (E) Double immunostaining in cultured DRG neurons showing co-colocalization of TLR3 with TRPV1 but not with NF200. Green arrows indicate NF200+ or TRPV1+ neurons, red arrows indicate TLR3+ neurons, and yellow allows indicate double-labeled neurons. Scale bars: 50 μm. (F) A Venn diagram showing the relationship of TLR3+, GRP+, and TRPV1+ populations in a DRG. Note that all TLR3+ cells also express GRP and TRPV1.

Nociceptive DRG neurons are involved in itch. TRPV1 and CGRP are indispensible for itch sensation. Given that all TRL3+ cells express these proteins, TRL3 could be a viable target for treating itch. 

Arthritic Pain, Nerve Sprouting and Neuroma Formation

Our friends, Drs Mantyh and Jimenez Andrade, have published important findings on the potential root cuases of age related Arthritic Pain: Juan M Jimenez-Andrade and Patrick W Mantyh. Sensory and sympathetic nerve fibers undergo sprouting and neuroma formation in the painful arthritic joint of geriatric mice. Note: our Chicken Polyclonal NF200 Antibody was used to label primary afferent sensory nerve fibers.

Overview: Introduction: Although the prevalence of arthritis dramatically increases with age, the great majority of preclinical studies concerning the mechanisms that drive arthritic joint pain have been performed in young animals. One mechanism hypothesized to contribute to arthritic pain is ectopic nerve sprouting; however, neuroplasticity is generally thought to be greater in young versus old nerves. Here we explore whether sensory and sympathetic nerve fibers can undergo a significant ectopic nerve remodeling in the painful arthritic knee joint of geriatric mice.

In other words, there is a clear root reason that the pain arthritis sufferers experience increases overtime. Here's some related data. Notice the increase in labeled nerves:

Images. Sensory nerve fiber sprouting and formation of neuroma-like structures in the painful geriatric arthritic knee joint. Schematic of a frontal view of a cross-sectioned mouse knee joint (A). The red square illustrates the synovial region from which the confocal images were obtained. Representative confocal images of calcitonin gene-related peptide (CGRP+), neurofilament 200 kDa (NF200+) sensory nerve fibers (yellow/orange) and growth associated protein (GAP43; marker of fibers undergo regeneration, yellow/orange) and DAPI labeled nuclei (blue) in knee joint sections (20 μm thick) of vehicle-injected (B,D,F) and CFA-injected (C,E,G ) mice. In vehicle-injected mice, a low level, regular pattern of innervation by CGRP+ and NF200+ fibers is observed in the synovial space of the knee joint. Twenty-eight days following the initial CFA injection, a significant number of CGRP+ and NF200+ nerve fibers have sprouted and have a disorganized appearance as compared to vehicle-injected mice. Note that, CGRP+ and NF200+ sprouted nerve fibers are localized in the synovium and are not observed in the meniscus of the joint. Furthermore, there was formation of neuroma-like structures in the synovium of the geriatric mice injected with CFA (G).

Related Reagents: Neuronal-Glial Markers-Astrocytes, Glia, Microglia, Olidogodendrocytes, Progenitors and Schwann Cell Markers.

P2X3 Receptors and Cool Science

Our P2X3 Receptor Antibodies are widely used and frequently published. This publication references use of our P2X3 Guinea Pig Antibody.

I like the "cool factor" in this study: Ji Z-G , Ito S , Honjoh T , Ohta H , Ishizuka T , et al. 2012 Light-evoked Somatosensory Perception of Transgenic Rats That Express Channelrhodopsin-2 in Dorsal Root Ganglion Cells. PLoS ONE 7(3): e32699. doi:10.1371/journal.pone.0032699.-"We have recently generated several transgenic lines of rat in which channelrhodopsin-2 (ChR2) transgene is driven by the Thy-1.2 promoter. In one of them, W-TChR2V4, some neurons were endowed with photosensitivity by the introduction of the ChR2 gene, coding an algal photoreceptor molecule. The DRG neurons expressing ChR2 were immunohistochemically identified using specific antibodies to the markers of mechanoreceptive or nociceptive neurons. Their peripheral nerve endings in the plantar skin as well as the central endings in the spinal cord were also examined. We identified that ChR2 is expressed in a certain population of large neurons in the DRG of W-TChR2V4. On the basis of their morphology and molecular markers, these neurons were classified as mechanoreceptive but not nociceptive. ChR2 was also distributed in their peripheral sensory nerve endings, some of which were closely associated with CK20-positive cells to form Merkel cell-neurite complexes or with S-100-positive cells to form structures like Meissner's corpuscles. These nerve endings are thus suggested to be involved in the sensing of touch. Each W-TChR2V4 rat showed a sensory-evoked behavior in response to blue LED flashes on the plantar skin. It is thus suggested that each rat acquired an unusual sensory modality of sensing blue light through the skin as touch-pressure. This light-evoked somatosensory perception should facilitate study of how the complex tactile sense emerges in the brain."

The researchers used Blue LED light to fire neurons involved somatosensory or tactile response!

Images. Distribution of ChR2V in the dorsal part of the spinal cord. A–C. Immunohistochemical localizationof ChR2V with the cell-type specific markers, NF200 (A), CGRP (B) or P2X3 (C). Scale bars indicate 40 µm.

Note that the receptors involved in Nociceptive Pain Sensing do not overlap with ChR2V. From this the authors conclude that ChR2V is involved in mechanoreception. This rat model should facilitate future study of how complex tactile perception, such as for texture, size and shape, is generated. We will keep you posted.

In the meantime check out our markers and antibodies for studying Neurotransmission and Synaptic Mechanisms.