Galanin receptors (GAL1, GAL2, GAL3). Galanin (1-29) is a non-selective endogenous agonist of the galanin receptor family, which consists of three G protein-coupled receptor subtypes: GAL1, GAL2, and GAL3. Upon binding to these receptors, galanin activates different intracellular signaling pathways depending on the receptor subtype and cell type. GAL1 and GAL3 preferentially couple to the Gi/o family of G proteins, leading to inhibition of adenylyl cyclase (decreased cAMP), activation of G protein-gated inwardly rectifying K+ channels (GIRK, causing hyperpolarization), and inhibition of voltage-gated Ca2+ channels. GAL2 couples to Gq/11, leading to activation of phospholipase C (PLC), increased inositol trisphosphate (IP3), and mobilization of intracellular Ca2+. Galanin (1-29) has high affinity for all three rodent galanin receptor subtypes, with Ki values of 0.98 nM (GAL1), 1.48 nM (GAL2), and 1.47 nM (GAL3). Through these receptors, galanin regulates feeding behavior, energy homeostasis, pain perception, neuroendocrine hormone release (e.g., growth hormone, prolactin, luteinizing hormone), seizure susceptibility, and cognition.

In vitro, Galanin (1-29) (rat, mouse) TFA is a non-selective galanin receptor agonist with high affinity for GAL1, GAL2, and GAL3 receptors. In receptor binding studies using rat brain or hypothalamic membranes or CHO cells expressing recombinant rat galanin receptors, galanin (1-29) displaces 125I-galanin with Ki values of 0.98 nM (GAL1), 1.48 nM (GAL2), and 1.47 nM (GAL3). In functional assays, galanin (1-29) (0.1-1000 nM) activates GIRK K+ currents in electrophysiological recordings from locus coeruleus neurons, dorsal raphe neurons, and hypothalamic arcuate nucleus neurons. In CHO cells expressing GAL1 or GAL3, galanin (1-29) inhibits forskolin-stimulated cAMP accumulation with IC50 in the low nM range (1-5 nM). In cells expressing GAL2, galanin (1-29) mobilizes intracellular Ca2+, measured by Fluo-4 fluorescence. In hypothalamic and pituitary cell cultures, galanin (1-29) stimulates the release of growth hormone (GH), prolactin (PRL), and luteinizing hormone (LH) in a concentration-dependent manner. In isolated pancreatic islets, galanin (1-29) inhibits glucose-stimulated insulin secretion (GSIS), contributing to its role in glucose homeostasis. Galanin (1-29) also modulates the release of neurotransmitters such as norepinephrine, dopamine, and serotonin in brain slice preparations. The TFA salt does not affect bioactivity.

In vivo, Galanin (1-29) (rat, mouse) TFA exerts potent central and peripheral effects. In rodents, intracerebroventricular (i.c.v.) or intrahypothalamic administration of galanin (1-29) (0.1-10 nmol) potently increases food intake (hyperphagia), particularly in the dark cycle and in response to high-fat diets. Galanin stimulates feeding by acting on GAL1 and GAL5 receptors in the paraventricular nucleus (PVN) and other hypothalamic nuclei. Galanin (1-29) also inhibits glucose-stimulated insulin secretion when administered intravenously or intraperitoneally. In models of neuropathic pain, intrathecal (i.t.) administration of galanin (1-29) (0.1-3 ug) produces antinociceptive effects, reducing thermal and mechanical hyperalgesia. In models of epilepsy, galanin (1-29) (i.c.v. or i.t.) has anticonvulsant effects, raising the seizure threshold and reducing seizure severity in pentylenetetrazole (PTZ) and kainate models. Galanin (1-29) modulates stress responses and depression-like behavior in the forced swim test (FST) and tail suspension test (TST). In the reproductive system, galanin (1-29) regulates luteinizing hormone (LH) and prolactin (PRL) secretion in ovariectomized and intact female rats. Galanin (1-29) also regulates body temperature and anxiety-like behaviors. In the periphery, galanin (1-29) inhibits gastrointestinal motility and secretion. These effects are mediated by the three galanin receptor subtypes with distinct tissue distributions. Galanin (1-29) is a research tool and is not a therapeutic drug.

For non-cellular binding assays, a radioligand binding assay can be performed. Membranes are prepared from rat hypothalamus, hippocampus, or transfected cells expressing specific galanin receptors (e.g., CHO cells expressing GAL1, GAL2, or GAL3). Tissues are homogenized in ice-cold buffer (50 mM Tris-HCl pH 7.4, 5 mM MgCl2, 0.1% BSA, 0.1% bacitracin, 0.1 mg/mL soybean trypsin inhibitor). Protein concentration is quantified (Bradford or BCA assay). In 96-well polypropylene plates, membranes (10-50 ug protein/well) are incubated with 0.05-0.1 nM 125I-galanin (porcine or rat) and varying concentrations of unlabeled Galanin (1-29) (0.01-10,000 nM) in binding buffer (total volume 200 uL/well). Non-specific binding is determined in the presence of 1 uM unlabeled galanin (1-29). After incubation for 60-90 minutes at 25degC with gentle shaking, bound and free radioligand are separated by rapid filtration through GF/B glass fiber filters pre-soaked in 0.3% polyethyleneimine (PEI) using a cell harvester. Filters are washed 3-4 times with ice-cold binding buffer, and filter-bound radioactivity is quantified in a gamma counter. IC50 values are determined using nonlinear regression (sigmoidal dose-response curve), and Ki values are calculated using the Cheng-Prusoff equation. For SPR, galanin receptors (e.g., GAL2) reconstituted in lipid nanodiscs can be immobilized on a sensor chip, and Galanin (1-29) (0.1-100 nM) is flowed over to determine binding affinity (KD). For competitive binding, a constant concentration of 125I-galanin and increasing cold galanin are used to determine IC50. The Ki values for galanin (1-29) at GAL1, GAL2, GAL3 are in the 1-5 nM range.

For cellular functional assays, CHO-K1 cells stably expressing rat GAL1, GAL2, or GAL3 receptors are used (or primary neuronal cultures from rat brain). Cells are seeded in 96-well plates at 2-5 × 10^4 cells/well in DMEM/F-12 with 10% FBS and incubated for 24 hours at 37degC, 5% CO2. For cAMP accumulation assays (GAL1/GAL3): On the assay day, medium is replaced with serum-free DMEM containing 0.5 mM IBMX (phosphodiesterase inhibitor) and pre-incubated for 20 minutes at 37degC. Cells are then treated with 20 uM forskolin (to stimulate cAMP production) plus Galanin (1-29) at concentrations 0.01-1000 nM for 30 minutes at 37degC. Cells are lysed, and intracellular cAMP levels are quantified using a homogeneous time-resolved fluorescence (HTRF) cAMP kit (Cisbio) or a chemiluminescence-based AlphaScreen kit. Percent inhibition of cAMP accumulation is calculated (maximal inhibition typically 60-80%). The EC50 or IC50 is derived from a sigmoidal dose-response curve. For Ca2+ mobilization assays (GAL2): Cells are loaded with Fluo-4 AM (2-5 uM in HBSS with 0.02% Pluronic F-127, 2.5 mM probenecid) for 30-60 minutes at 37degC. After loading, cells are washed twice with HBSS and resuspended in HBSS containing 0.1% BSA. The plate is placed in a fluorescence plate reader (FlexStation 3, FLIPR Tetra). Baseline fluorescence (excitation 494 nm, emission 516 nm) is recorded for 30 seconds. Galanin (1-29) (0.1-1000 nM) is injected automatically, and fluorescence is measured for 2-5 minutes. Peak fluorescence minus baseline (deltaF) is plotted against log10(concentration) to generate a concentration-response curve, and EC50 is calculated. For GIRK channel activation assays (GAL1/GAL3): Xenopus oocytes are co-injected with cRNAs encoding rat GIRK1/GIRK2 channels and rat GAL1 or GAL3 receptor. After 2-5 days of expression, two-electrode voltage clamp recordings are performed. Galanin (1-29) (0.1-1000 nM) is applied to activate GIRK channels, and the induced K+ current is measured. The EC50 is typically in the low nM range. For each assay condition, at least three independent experiments are performed in triplicate.

For in vivo studies, adult male or female Sprague-Dawley rats (200-300 g) or C57BL/6J mice (20-30 g) are used. Galanin (1-29) (rat, mouse) TFA is dissolved in sterile artificial cerebrospinal fluid (aCSF), 0.9% saline, or PBS (pH 7.4) at concentrations of 0.1-5 ug/uL, and stored in aliquots at -80degC to avoid repeated freeze-thaw cycles. For intracerebroventricular (i.c.v.) administration: Rats or mice are anesthetized with isoflurane or ketamine/xylazine and placed in a stereotaxic frame. A 26-gauge guide cannula is implanted into the lateral ventricle (rat: AP -0.9 mm, ML +1.5 mm, DV -3.5 mm from bregma; mouse: AP -0.5 mm, ML +1.0 mm, DV -2.5 mm). After 5-7 days of recovery, animals are fasted overnight (for feeding studies) or used without fasting. Galanin (1-29) (0.1-5 nmol in 1-5 uL volume) is injected i.c.v. over 1-2 minutes using a microinfusion pump (0.5-1 uL/min), and the injector is left in place for an additional 1-2 minutes to prevent backflow. Control animals receive aCSF or scrambled peptide. For food intake measurement: Immediately after i.c.v. injection, pre-weighed food pellets are placed in the cage, and cumulative food intake is measured at 1, 2, 4, and 24 hours (for rats) or at 0.5, 1, 2, 4, and 24 hours (for mice). For pain studies (intrathecal (i.t.) administration): Under isoflurane anesthesia, a PE-10 catheter is inserted into the subarachnoid space between L4 and L5 vertebrae and advanced 1-2 cm (mice) or 3-5 cm (rats) toward the lumbar enlargement. The external part is externalized at the back of the neck, and the wound is sutured. After 5-7 days recovery, Galanin (1-29) (0.1-10 ug in 5-10 uL volume) is injected i.t., followed by 10 uL saline flush. Pain sensitivity is assessed using tail-flick (radiant heat), hot plate (55degC), or von Frey filaments (mechanical allodynia) before and at 15, 30, 60, 90, and 120 minutes post-injection. For neuroendocrine studies: Blood samples (100-200 uL) are collected from the tail vein at various time points before and after i.c.v. or i.p. injection of galanin (1-29) (0.5-10 nmol i.c.v.; 0.1-1 mg/kg i.p.). Plasma is separated and stored at -80degC. Growth hormone (GH), prolactin (PRL), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and corticosterone are measured by specific radioimmunoassays (RIA) or ELISAs. For studies of glucose homeostasis and insulin secretion: Galanin (1-29) is administered intravenously (10-100 ug/kg) or intraperitoneally (0.1-1 mg/kg) 10-15 minutes prior to an intraperitoneal glucose tolerance test (IPGTT) (glucose 1-2 g/kg i.p.). Blood glucose is measured at 0, 15, 30, 60, 90, 120 min post-glucose, and plasma insulin is measured by ELISA. Galanin (1-29) should reduce glucose-stimulated insulin secretion, leading to elevated blood glucose levels compared to vehicle controls. For anticonvulsant studies: Mice or rats are injected i.c.v. with galanin (1-29) (0.1-5 nmol) 15-30 minutes prior to pentylenetetrazole (PTZ, 40-60 mg/kg i.p.) or kainate (15-30 mg/kg i.p.). Seizure activity (latency to first seizure, seizure severity score, number of seizures) and mortality are recorded. Galanin is expected to reduce seizure severity and increase survival. In all studies, appropriate controls (vehicle, scrambled peptide) must be included. Galanin (1-29) is generally well-tolerated at the doses described, with no reports of overt acute toxicity. The experiments must comply with institutional animal care and use committee (IACUC) guidelines.

No specific pharmacokinetic data are available for Galanin (1-29), rat/mouse TFA. As a 29-amino acid neuropeptide (MW ~3.2 kDa), galanin (1-29) is rapidly cleared from the systemic circulation when administered peripherally (i.v., i.p.). Its plasma half-life is on the order of a few minutes (2-10 minutes) due to renal clearance (glomerular filtration) and proteolytic degradation (by neutral endopeptidases, dipeptidyl peptidases, and other tissue peptidases). For central effects, galanin (1-29) is typically administered directly into the CSF (i.c.v., i.t.) or locally into brain parenchyma to bypass the blood-brain barrier (BBB). Following i.c.v. administration, the peptide distributes within the ventricular system, diffuses into brain parenchyma (e.g., hypothalamus, hippocampus, brainstem), and is cleared from the CSF by bulk flow and enzymatic degradation. The half-life in CSF is estimated to be 30-60 minutes in rodents. Galanin (1-29) binds to plasma proteins (albumin) with low-to-moderate affinity, which may extend its half-life slightly. The TFA salt form does not affect the PK properties. Galanin (1-29) is not a therapeutic drug; it is a research tool. Detailed PK parameters (AUC, Cmax, Tmax, t1/2, CL, Vd) are not routinely determined for this peptide in research contexts, but can be measured using radiolabeled (125I-galanin) or fluorescently labeled galanin (e.g., FITC-galanin). In such studies, galanin (1-29) is found to distribute widely in the brain after i.c.v. administration, with highest levels in the hypothalamus, hippocampus, and brainstem. Galanin (1-29) is rapidly cleared from the blood (t1/2 ~2-5 min) after i.v. administration in rodents.

No specific toxicity data are available for Galanin (1-29) (rat, mouse) TFA. Galanin (1-29) is an endogenous neuropeptide found in many species, including rodents and humans. As an endogenous substance, it is generally well-tolerated and has a low inherent toxicity at physiological concentrations. In research studies, acute administration of galanin (1-29) at doses up to 10 nmol (i.c.v., ~30 ug/rat) or 1 mg/kg (i.p., ~200-300 ug/rat) does not cause overt signs of toxicity (e.g., mortality, severe weight loss, seizures, organ dysfunction) in rodents. However, pharmacological effects (e.g., increased food intake, reduced pain sensitivity, reduced insulin secretion) are observed at lower doses (0.1-1 nmol i.c.v. or 0.1-1 mg/kg i.p.). At very high doses (>10 nmol i.c.v. or >5 mg/kg i.p.), non-specific effects (e.g., sedation, hypothermia, motor impairment) may occur, but such doses are rarely used. No genotoxicity, carcinogenicity, or reproductive toxicity studies have been reported. The TFA salt (trifluoroacetate) is present in small, stoichiometric amounts and is generally considered non-toxic. Galanin (1-29) TFA is for research use only and is not intended for human or therapeutic use. Standard laboratory safety precautions (gloves, lab coat, eye protection) should be used when handling the powder or solutions.

[1]. Cloning and expressional characterization of a novel galanin receptor. Identification of different pharmacophores within galanin for the three galanin receptor subtypes. J Biol Chem. 1997;272(51):31949-31952.

[2]. Regulation of kindling epileptogenesis by hippocampal galanin type 1 and type 2 receptors: The effects of subtype-selective agonists and the role of G-protein-mediated signaling. J Pharmacol Exp Ther. 2006;318(2):700-708.

In rats and mice, galanin is a 29-amino acid neuropeptide (Galanin-29), while in humans, it is a 30-amino acid peptide (Galanin-30) with a different C-terminal extension. Galanin (1-29) (rat, mouse) is the full-length endogenous peptide sequence found in rodents and is widely used in pharmacological studies because it recapitulates the biological activity of endogenous galanin. The peptide is derived from preprogalanin, which is processed to produce galanin (1-29) and a galanin message-associated peptide (GMAP). Galanin is widely distributed in the central and peripheral nervous systems, especially in the hypothalamus, brainstem, spinal cord, and enteric nervous system. Galanin regulates diverse functions including appetite, energy homeostasis, pain, memory and cognition, stress and anxiety, neuroendocrine secretion, and seizure activity. In particular, galanin plays a dual role in metabolic control: centrally, it stimulates food intake, while peripherally, it inhibits insulin secretion, thereby promoting hyperglycemia. The TFA salt is used to improve peptide solubility and stability. Galanin (1-29) (rat, mouse) TFA is for research use only; it is not an approved therapeutic drug. It is widely used as a tool to study galaninergic signaling and receptor pharmacology, as well as to validate the effects of galanin receptor antagonists. The peptide is also used to evaluate galanin levels in tissues by radioimmunoassay (RIA) or enzyme immunoassay (EIA). For receptor subtype selectivity studies, more selective agonists (e.g., Gal(2-11) for GAL1, Gal(B2) for GAL2) are available, but the full-length 1-29 peptide is still the standard for non-selective activation of galanin receptors.

C143H212F3N43O43

3278.47

Galanin (1-29)(rat, mouse);114547-31-8

Solid powder

2934.99.9001

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 (e.g. under nitrogen), avoid exposure to moisture and light.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*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.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)