| Size | Price | Stock | Qty |
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| 1mg |
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| 5mg |
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| Other Sizes |
| Targets |
IC50: 30 nM (PACAP type I receptor), 600 nM (PACAP type II receptor VIP1), 40 nM (PACAP type II receptor VIP2)[1]
PACAP (6-38) is a high-affinity antagonist for the PAC1 receptor, which is selective for PACAP over VIP. It also has antagonist activity at the VPAC1 and VPAC2 receptors (which bind both PACAP and VIP), but with lower affinity. The IC50 values are: 30 nM for the PACAP type I receptor (PAC1), 600 nM for the PACAP type II receptor VIP1 (VPAC1), and 40 nM for the PACAP type II receptor VIP2 (VPAC2). This selectivity makes PACAP(6-38) a useful tool for distinguishing PACAP-specific effects from those mediated by VIP. |
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| ln Vitro |
It is also possible to detect a rise in dopamine (DA) content by HPLC analysis and/or cell proliferation detected by the MTT assay by Dexamethasone (DEX). These effects can be prevented by PACAP (6-38) at concentrations high enough to block the PACAP type 1 (PAC1) receptor. This rise in DA content by 1 μM DEX is strongly inhibited by pretreatment with PAC1 receptor antagonist PACAP(6-38) at 0.1 or 1 μM for 2 hours. DEX promotes cell growth, as demonstrated by the MTT experiment. Furthermore, PACAP's pre-incubation inhibits this effect as well (6-38). DA content and cell proliferation are unaffected by PACAP(6-38) at 1μM for a 24-hour period. It has been reported, meanwhile, that PACAP(6-38) at 0.3 μM can inhibit the spontaneous buildup of tyrosine hydroxylase (TH) in differentiated retinal cultured cells over a period of five days[2].
In cell lines expressing recombinant PAC1 or VPAC receptors, PACAP (6-38) (0.01-10 uM) competitively inhibits PACAP-38-induced cAMP accumulation. In PC12 cells (pheochromocytoma cells that endogenously express PAC1), the antagonist (1 uM) blocks PACAP-38-stimulated neurite outgrowth and ERK phosphorylation. In smooth muscle and neuronal preparations, the compound dose-dependently shifts the PACAP-38 concentration-response curve to the right (increases EC50) without affecting the maximal response. |
| ln Vivo |
In NGF-OE mice, intravesical injection of PACAP (6-38), a PAC1 receptor antagonist, significantly increases both the void volume (2.5-fold) and intercontraction interval (2.0-fold). NGF-OE mice's baseline bladder pressure is likewise reduced by intravesical administration of PACAP (6-38). While PACAP (6-38) (300 nM) administered intravenously considerably (p≤0.01) lowers pelvic sensitivity in NGF-OE mice, it has no impact in WT animals[3].
In NGF-overexpressing (NGF-OE) transgenic mice (a model of chronic bladder overactivity), intravesical (bladder) injection of PACAP (6-38) (10 uM, 100 uL) significantly increases both the void volume (2.5-fold) and intercontraction interval (2.0-fold), reducing bladder hyperactivity. This demonstrates the role of endogenous PACAP in bladder function. In rodent models of neurogenic inflammation, PACAP (6-38) blocks PACAP-induced vasodilation and plasma protein extravasation. In models of pain, intrathecal injection of PACAP(6-38) reduces mechanical and thermal hyperalgesia, confirming a role for PACAP in pain transmission. |
| Enzyme Assay |
A competition binding assay is performed using membranes from CHO or HEK293 cells stably expressing the human PAC1 or VPAC2 receptor. Membranes (10-20 ug protein) are incubated with 50 pM ¹2⁵I-PACAP-27 (radioligand) and increasing concentrations (0.01 nM - 10 uM) of PACAP (6-38) TFA in binding buffer (20 mM HEPES, pH 7.4, 100 mM NaCl, 5 mM MgCl2, 1 mM CaCl2, 0.1% BSA, 0.1 mg/mL bacitracin) for 60 minutes at room temperature. Bound radioligand is separated by rapid vacuum filtration through GF/C filters (pre-soaked in 0.3% polyethyleneimine) and washed 3 times with ice-cold buffer. Filters are counted in a gamma counter. Nonspecific binding is determined with 1 uM PACAP-27. The equilibrium dissociation constant (Kd) and binding affinity (Ki) are calculated using one-site competition binding analysis.
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| Cell Assay |
HeLa cells stably transfected with human PAC1 receptor (HeLa-PAC1) are seeded in 96-well plates (2×10⁴ cells/well). Cells are washed with HBSS and incubated with 100 uM PACAP (6-38) TFA (for antagonist studies) or with the compound 15 minutes prior to adding 10 nM PACAP-38. After 15 min at 37degC, cells are lysed in 0.1 M HCl. The lysate is neutralized, and intracellular cAMP is measured by ELISA. PACAP (6-38) alone (1 uM) should not elevate cAMP levels (antagonist activity). For EC50 shift assays, increasing concentrations of PACAP (6-38) (e.g., 0.01-10 uM) are added prior to a fixed concentration of PACAP-38 (e.g., 10 nM). Alternatively, a Ca2+ flux assay is performed in CHO-PAC1 cells. Cells are loaded with Fluo-4 AM (2 uM, 30 min, 37degC), stimulated with 10 nM PACAP-38 in the presence of varying concentrations (0.001-10 uM) of PACAP (6-38), and fluorescence (ex/em = 485/535 nm) is recorded every 2 seconds for 1 minute. The antagonist IC50 is calculated by non-linear regression.
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| Animal Protocol |
Adult female NGF-OE transgenic mice (8-10 weeks old, ~25 g, n=5-8/group) are anesthetized with isoflurane. For intravesical (bladder) injection, a 27-gauge needle is inserted through the urethra into the bladder lumen, and urine is removed. PACAP (6-38) TFA (100 uL, 10 uM, dissolved in sterile saline) or vehicle is infused and left in the bladder for 10 minutes. After removal, the mouse is placed in a metabolic cage, and voiding behavior is recorded continuously for 60 minutes. Intercontraction interval (ICI), void volume, and pressure threshold (if using cystometry) are measured. In rat models of pain: Male Sprague-Dawley rats (250-300 g) are intrathecally (i.t.) cannulated via the lumbar region (L4-L5). After recovery, PACAP (6-38) (0.1, 1, 10, 30 nmol in 5 uL saline) or vehicle is injected intrathecally. Thermal hyperalgesia is measured by the Hargreaves paw withdrawal test (plantar test, using a radiant heat source). Mechanical allodynia is assessed by von Frey filaments. The investigator is blinded to treatment groups. For cardiovascular studies, anesthetized rats are instrumented with arterial catheters for blood pressure measurement. PACAP(6-38) (0.1-1 mg/kg, i.v. bolus) is administered 5-10 min prior to PACAP-38 challenge. Mean arterial pressure (MAP) and heart rate are recorded continuously.
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| ADME/Pharmacokinetics |
Pharmacokinetics of PACAP(6-38) itself are not well-studied. As a 33-amino acid peptide, its plasma half-life is expected to be very short (<30 minutes). When administered intravenously (1 mg/kg), peak plasma concentration likely occurs within 5 minutes, followed by rapid clearance (predominantly renal and proteolytic). For intrathecal (i.t.) administration (rat), the half-life in CSF is longer (likely 30-60 min). For bladder instillation, very little systemic absorption occurs.
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| Toxicity/Toxicokinetics |
Dedicated toxicity studies are not reported. In animal experiments at pharmacologically effective doses (e.g., 10-30 nmol i.t. in rats, 10 uM bladder instillation in mice), no overt signs of toxicity or adverse behavioral effects are observed. As a competitive antagonist, the compound is well-tolerated. The main safety consideration is the potential to block endogenous PACAP signaling, which could have effects on stress responses, cardiovascular regulation, and sensory processing. Long-term toxicity data are not available.
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| References |
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| Additional Infomation |
PACAP (6-38) is a widely used research reagent and is not approved for human use. It is one of the most commonly employed tools for blocking PACAP signaling in vitro and in vivo, allowing researchers to separate PACAP's effects from those of the related peptide VIP. The compound is stable as a lyophilized powder at -20degC for 2-3 years. Reconstitute in sterile water or 0.9% saline for injection. The peptide is prone to aggregation; vortex gently, avoid freeze-thaw cycles. For long-term storage, aliquot and store at -80degC.
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| Molecular Formula |
C184H301N56FO47S
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| Molecular Weight |
4138.76
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| Related CAS # |
PACAP (6-38), human, ovine, rat;143748-18-9
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| Appearance |
Solid powder
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| HS Tariff Code |
2934.99.9001
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| Storage |
Powder -20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month Note: Please store this product in a sealed and protected environment, avoid exposure to moisture. |
| Shipping Condition |
Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)
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| Solubility (In Vitro) |
DMSO :~100 mg/mL (~24.16 mM)
H2O :~50 mg/mL (~12.08 mM) |
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| Solubility (In Vivo) |
Solubility in Formulation 1: ≥ 2.5 mg/mL (0.60 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution. Solubility in Formulation 2: ≥ 2.5 mg/mL (0.60 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly. View More
Solubility in Formulation 3: 100 mg/mL (24.16 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication. |
| Preparing Stock Solutions | 1 mg | 5 mg | 10 mg | |
| 1 mM | 0.2416 mL | 1.2081 mL | 2.4162 mL | |
| 5 mM | 0.0483 mL | 0.2416 mL | 0.4832 mL | |
| 10 mM | 0.0242 mL | 0.1208 mL | 0.2416 mL |
*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.
Calculation results
Working concentration： mg/mL；
Method for preparing DMSO stock solution： mg drug pre-dissolved in μL DMSO (stock solution concentration mg/mL). Please contact us first if the concentration exceeds the DMSO solubility of the batch of drug.
Method for preparing in vivo formulation:：Take μL DMSO stock solution, next add μL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH2O，mix and clarify.
(1) Please be sure that the solution is clear before the addition of next solvent. Dissolution methods like vortex, ultrasound or warming and heat may be used to aid dissolving.
(2) Be sure to add the solvent(s) in order.
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