Zoccal DB, Silva JN, Barnett WH, Lemes EV, Falquetto B, Colombari E, Molkov YI, Moreira TS, Takakura AC (2018) Interaction between the retrotrapezoid nucleus and the parafacial respiratory group to regulate active expiration and sympathetic activity in rats. Am J Physiol Lung Cell Mol Physiol 315(5):L891-L909. doi: 10.1152/ajplung.00011.2018

Objective: To investigate the microcircuitry responsible for the distribution of the excitatory signals to the the parafacial respiratory group (pFRG) and the the respiratory central pattern generator (rCPG) in conditions of high CO2.

Summary: The activation of the pFRG late-E neurons during hypercapnia require glutamatergic inputs from the RTN neurons that intrinsically detect changes in CO2/pH.

Usage: Bilateral injections of SSP-SAP (0.6 ng in 100 nL of saline per side).

Related Products: SSP-SAP (Cat. #IT-11)

Lénárd L, László K, Kertes E, Ollmann T, Péczely L, Kovács A, Kállai V, Zagorácz O, Gálosi R, Karádi Z (2018) Substance P and neurotensin in the limbic system: Their roles in reinforcement and memory consolidation. Neurosci Biobehav Rev 85:1-20. doi: 10.1016/j.neubiorev.2017.09.003

Summary: A specific neurotoxin, SSP-SAP can cause selective ablation of NK1 receptor expressing cells. This lesion in the BLA of rats resulted in anxiogenic effect, while in the CeA had no effect in EPM test.

See: Truitt WA et al. Anxiety-like behavior is modulated by a discrete subpopulation of interneurons in the basolateral amygdala. Neuroscience 160:284-294, 2009.

Related Products: SSP-SAP (Cat. #IT-11)

Souza GMPR, Kanbar R, Stornetta DS, Abbott SBG, Stornetta RL, Guyenet PG (2018) Breathing regulation and blood gas homeostasis after near complete lesions of the retrotrapezoid nucleus in adult rats. J Physiol 596(13):2521-2545. doi: 10.1113/JP275866

Objective: To test how important the retrotrapezoid nucleus (RTN) is to PCO2 homeostasis and breathing during sleep or wake.

Summary: Near complete RTN destruction in rats virtually eliminates the CRC but HVR persists and sighing and the state-dependence of breathing are unchanged. Under normoxia, RTN lesions cause no change in VE but alveolar ventilation is reduced by at least 21%, probably because of increased physiological dead volume. RTN lesions do not cause sleep apnea during SWS, even under hyperoxia.

Usage: A total of 6 microinjections (120 nl/injection; 3 rostrocaudally aligned injections per side) were made 100-200 μm below the lower edge of the facial motor nucleus 2 mm lateral to the midline. Experimental rats received either 0.6 ng, 1.2 ng, or 2.4 ng of SSP-SAP per injection.

Related Products: SSP-SAP (Cat. #IT-11)

Araldi D, Ferrari LF, Levine JD (2018) Role of GPCR (mu-opioid)-receptor tyrosine kinase (epidermal growth factor) crosstalk in opioid-induced hyperalgesic priming (type II). Pain 159(5):864-875. doi: 10.1097/j.pain.0000000000001155

Objective: To determine the the mechanisms mediating the induction of opioid-induced hyperalgesia and the prolongation of prostaglandinE2-induced hyperalgesia in type II hyperalgesic priming.

Summary: Understanding the mechanisms responsible for the induction of type II hyperalgesic priming, a form of neuroplasticity in the peripheral terminal of the primary afferent nociceptor, may provide useful information for the design of drugs with improved therapeutic profiles to treat neuroplasticity induced by chronic use of opioids.

Usage: SSP-SAP was prepared in saline (5 ng/mL), and 20 mL was injected intrathecally into rats, 14 days before nociceptive tests.

Related Products: SSP-SAP (Cat. #IT-11)

Vetter I (2018) Toxins in Neurobiology: New tools from old molecules. Neurosci Lett 679:1-3. doi: 10.1016/j.neulet.2018.05.008

Summary: The selective ablation of neurokinin-1 receptor-expressing neurons by SP-SAP revealed a key role for the preBötzinger complex in the generation of respiratory rhythm. Toxin-mediated neuronal ablation may also find therapeutic applications, such as the treatment of severe refractory pain in terminally ill patients by intrathecal SP-SAP which causes selective loss of neurokinin-1 receptor-expressing neurons in the spinal cord dorsal horn.

Related Products: SSP-SAP (Cat. #IT-11)

Strichartz G, Khasabov S, Barr T, Wang J, Simone D (2018) Modulation of chronic post-thoracotomy pain by NK-1 neurons in the rostral ventromedial medulla is not paralleled by changes spinal MAPKinase activation. J Pain 19:S14. doi: 10.1016/j.jpain.2017.12.065

Objective: To evaluate SSP-SAP in treatment of tactile hypersensitivity for Chronic Post-Thoractotomy Pain (CPTP).

Summary: SSP-SAP 3 weeks before thoracotomy and rib retraction (TRR) was able to completely prevent CPTP, assayed by tactile hypersensitivity.

Usage: Ablation of Neurokinin-1 receptor (NK-1R)- expressing neurons in the rat rostral ventromedial medulla (RVM), by micro-injection of the specific neurotoxin SSP-SAP.  No effect with treatment of control, Blank-SAP (IT-21).

Related Products: SSP-SAP (Cat. #IT-11), Blank-SAP (Cat. #IT-21)

Park HW, Kim H-L, Park YS, Kim I-B (2018) The transient intermediate plexiform layer, a plexiform layer-like structure temporarily existing in the inner nuclear layer in developing rat retina. Exp Neurobiol 27:28-33. doi: 10.5607/en.2018.27.1.28

Related Products: SSP-SAP (Cat. #IT-11)

Ferrari LF, Khomula EV, Araldi D, Levine JD (2018) CD44 signaling mediates high molecular weight hyaluronan-induced antihyperalgesia. J Neurosci 38(2):308-321. doi: 10.1523/JNEUROSCI.2695-17.2017

Objective: To study the role of the cognate hyaluronan receptor, CD44, signaling in anti-hyperalgesia induced by high molecular weight hyaluronan (HMWH).

Summary: These results demonstrate the central role of CD44 signaling in HMWH-induced anti-hyperalgesia, and establish it as a therapeutic target against inflammatory and neuropathic pain.

Usage: Both IB4-SAP and SSP-SAP were diluted in saline to doses previously shown to deplete nonpeptidergic (3.2 mcg/rat for IB4-SAP) and peptidergic (100 ng/rat for SSP-SAP) fibers. The toxins were administered intrathecally, in a volume of 20 mcl, 14 d before intradermal injection of LMWH on the dorsum of the hindpaw. Treatment with either conjugate, or a combination of the two, did not significantly affect mechanical nociceptive threshold.

Related Products: IB4-SAP (Cat. #IT-10), SSP-SAP (Cat. #IT-11), Anti-CD44-SAP (Cat. #IT-72)

Barnett WH, Molkov YI, Lemes E, Falqueto B, Colombari E, Takakura AT, Moreira TS, Zoccal DB (2017) Local glutamatergic transmission in the RTN/pFRG is critical for active expiration and sympathetic overactivity during hypercapnia. Neuroscience 2017 Abstracts 233.1 / FF22. Society for Neuroscience, Washington, DC.

Summary: The retrotrapezoid nucleus (RTN) contains chemosensitive cells that distribute CO -dependent excitatory drive to the brainstem respiratory network. This drive facilitates the function of the respiratory central pattern generator (CPG), modulates sympathetic activity and determines the emergence of active expiration during hypercapnia via activation of the late expiratory (late-E) oscillator in the parafacial respiratory group (pFRG). However, the microcircuitry responsible for distribution of the chemoreflex signal to the pFRG and the respiratory CPG is not well understood. Previously, we developed a computational model of the brainstem respiratory network, which was subsequently extended to include the central and peripheral chemoreflexes as well as presympathetic circuits. We present here experiments performed on the decerebrated, arterially-perfused in situ rat, aimed to test a key assumption of this model that chemosensitive and late-E neurons in the RTN/pFRG are two distinct populations, and the latter receives local glutamatergic input from the former. The model predicts: (1) suppression of RTN chemosensitive neurons will diminish the changes to the respiratory pattern and the emergence of active expiration associated with hypercapnia; (2) the disruption of local glutamatergic neurotransmission in the RTN will specifically suppress active expiration and the appearance of late-E discharges in the sympathetic motor output. To test prediction (1) we lesioned NK1 -positive chemosensitive neurons of the RTN with microinjections of substance P-saporin (SSP-SAP) conjugate. This suppressed the emergence of late-E activity in abdominal (AbN) and sympathetic nerves, and attenuated the increase in phrenic burst amplitude during hypercapnia. However, SSP-SAP and control animals exhibited late-E AbN activity in response to peripheral chemoreflex activation. Prediction (2) was tested with bilateral microinjections of kynurenic acid (Kyn, 100 mM) in the RTN/pFRG, which suppressed the emergence of late-E AbN activity but not the change in phrenic nerve amplitude during hypercapnia. Our results support the notion that RTN chemosensitive neurons are critical for inspiratory and expiratory reflex responses to hypercapnia. Our findings indicate that activation of late-E neurons in the pFRG during hypercapnia requires glutamatergic inputs from a separate neuronal population in the RTN that intrinsically detects changes in CO . During peripheral chemoreflex stimulation, pFRG late-E neurons are activated via excitatory pathways bypassing the RTN central chemoreceptors. We recapitulate these results in our computational model.

Related Products: SSP-SAP (Cat. #IT-11)

Fu C, Xue J, Wang R, Chen J, Ma L, Liu Y, Wang X, Guo F, Zhang Y, Zhang X, Wang S (2017) Chemosensitive Phox2b-expressing neurons are crucial for hypercapnic ventilatory response in the nucleus tractus solitarius. J Physiol 595:4973-4989.. doi: 10.1113/JP274437

Objective: To investigate whether paired-like homeobox 2b  (Phox2b)-expressing NTS neurons are recruited in hypercapnic ventilatory response (HCVR)  and whether these neurons exhibit intrinsic chemosensitivity.

Summary: Respiratory deficits caused by injection of SSP-SAP into the NTS are attributable to proportional lesions of CO2/H+-sensitive Phox2b-expressing neurons.

Usage: Two protocols were applied for SSP-SAP injections. In immunostaining experiments, to determine how many Phox2b-containing cells were destroyed, a total volume of 100 nl of PBS containing 6 ng of SSP-SAP (3 ng in 50 nl; 2 injections) was injected into one side of the NTS and the contralateral NTS was used as a control (no injection).  For in vivo experiments, to determine whether loss of Phox2b cells led to impaired HCVR, bilateral injections with a total volume of 200 nl of PBS containing 6 ng (1.5 ng in 50 nl per injection; 2 injections per side) or 12 ng (3 ng in 50 nl per injection; two injections per side) of toxin into NTS.  Breathing was studied in conscious, freely moving mice treated with SSP-SAP and Blank-SAP.

Related Products: SSP-SAP (Cat. #IT-11), Blank-SAP (Cat. #IT-21)