Protease activated receptor 2 (PAR2) activation causes migraine-like pain behaviors in mice

BACKGROUND

Pain is the most debilitating symptom of migraine. The cause of migraine pain likely requires activation of meningeal nociceptors. Mast cell degranulation, with subsequent meningeal nociceptor activation, has been implicated in migraine pathophysiology. Degranulating mast cells release serine proteases that can cleave and activate protease activated receptors. The purpose of these studies was to investigate whether protease activated receptor 2 is a potential generator of nociceptive input from the meninges by using selective pharmacological agents and knockout mice.

METHODS

Ratiometric Ca++ imaging was performed on primary trigeminal and dural cell cultures after application of 2at-LIGRL-NH2, a specific protease activated receptor 2 agonist. Cutaneous hypersensitivity and facial grimace was measured in wild-type and protease activated receptor 2-/- mice after dural application of 2at-LIGRL-NH2 or compound 48-80, a mast cell degranulator. Behavioral experiments were also conducted in mice after dural application of 2at-LIGRL-NH2 (2AT) in the presence of either C391, a selective protease activated receptor 2 antagonist, or sumatriptan.

RESULTS

2at-LIGRL-NH2 evoked Ca2+ signaling in mouse trigeminal neurons, dural fibroblasts and in meningeal afferents. Dural application of 2at-LIGRL-NH2 or 48-80 caused dose-dependent grimace behavior and mechanical allodynia that were attenuated by either local or systemic application of C391 as well as in protease activated receptor 2-/- mice. Nociceptive behavior after dural injection of 2at-LIGRL-NH2 was also attenuated by sumatriptan.

CONCLUSIONS

Functional protease activated receptor 2 receptors are expressed on both dural afferents and fibroblasts and activation of dural protease activated receptor 2 produces migraine-like behavioral responses. Protease activated receptor 2 may link resident immune cells to meningeal nociceptor activation, driving migraine-like pain and implicating protease activated receptor 2 as a therapeutic target for migraine in humans.

Effect of galactomannans on the thermal and rheological properties of sago starch

The thermal and rheological properties of sago starch have been studied in the presence of various concentrations of locust bean gum and guar gum of various molecular masses. At the concentrations studied (<1%) the galactomannans gave rise to only a very slight increase in the gelatinization temperature (up to 0.6 degrees C), and the gelatinization enthalpy remained constant within experimental error. For the low molecular mass galactomannans, depending on the concentration, the storage modulus, G', of the mixtures remained constant or actually decreased, and tan delta remained very low (0.01-0.03 at 0.1 Hz), indicating strong elastic gels. For the higher molecular mass samples G' increased significantly; however, the loss modulus, G' ', increased proportionally to a greater extent, and at 1% galactomannan tan delta was approximately 0.20 at 0.1 Hz, indicating a reduction in elastic character. The systems were shown to undergo phase separation, and the variations in rheological properties have been discussed in the context of their phase behavior and the relative rates of the phase separation and gelation processes. The presence of galactomannans significantly improved the freeze-thaw stability.

Effect of sugars on the thermal and rheological properties of sago starch

Studies have been undertaken to investigate the effect of sugars on the thermal and rheological properties of sago starch. Sugars were found to increase the gelatinization temperature T(gel), and gelatinization enthalpy DeltaH. T(gel) and DeltaH increased in the following order: control (water alone) < ribose < fructose < glucose < maltose < sucrose. The increase in DeltaH was greater for 50% starch compared to 10% starch samples. The swelling factors in the presence of sugar were higher compared to the control for sugar concentrations below 25% but were lower at sugar concentration greater than 25%. These effects are discussed in terms of the antiplaticizing effect of the sugars compared to water, the influence of sugar-starch interactions and also the effect of the sugars on water structure. The storage modulus G', the rate constant of gelation k, and the gel strength were significantly reduced in the presence of sugars. Generally G' and k decreased in the following order: control (water alone) > hexose > disaccharide > pentoses. This has been attributed to the reduced proportion of amylose leached following gelatinizatison. In the presence of hexoses the freeze-thaw stability of starch gels decreased while in the presence of disaccharides and pentoses the freeze-thaw stability was slightly improved.

Effect of salts on the gelatinization and rheological properties of sago starch

The effects of various salts on the gelatinization and rheological properties of sago starch have been studied using differential scanning calorimetry, small deformation oscillation, and large deformation techniques. The presence of salts affected the gelatinization peak temperature, T(p), gelatinization enthalpy, DeltaH, swelling properties, storage modulus, G', gel strength, GS, and gelation rate constants, k, depending on the type of salt and the concentration. Their influence followed the Hofmeister series, and the effect of anions was more pronounced than that of cations. Sulfate ions increased T(p), G', GS, and k and reduced the swelling properties, whereas iodide and thiocyanate ions reduced T(p), G', GS, and k but increased the swelling properties. For all of the salts studied except for Na(2)SO(4), T(p) increased to a maximum and then decreased again at higher salt concentrations while DeltaH reduced with concentration. In the presence of MgCl(2), CaCl(2), and LiCl complex behavior was observed such that at approximately 3.5 M MgCl(2) and CaCl(2) and 8 M LiCl the starch samples were gelatinized at room temperature, whereas at much higher concentration T(p) increased again and the transition became exothermic.

Curcumin in a model skin lotion formulation

A lamellar liquid crystalline region was identified in a typical skin lotion formulation system composed of a mixture of isostearic acid and triethanolamine (TEA) at 65:35 (w/w), decane, and water (the temperature was controlled at 30 degrees C). The interlayer spacings were determined by a small-angle X-ray diffraction technique. Incorporation of a natural dye, curcumin, resulted in lower interlayer spacings and higher penetration of water into the layered structure. However, the higher penetration of water was not apparent at all compositions of isostearic acid:TEA, decane, and water.

Relationship of ovarian contents to plasma progesterone concentration in the swamp buffalo (Bubalus bubalis)

Using rectal palpation and laparoscopy, the relationship of ovarian contents to plasma progesterone concentration during the oestrous cycle, early pregnancy and post partum periods in the swamp buffalo (Bubalus bubalis) was studied. During the oestrous cycle, four stages in the lifespan of the corpus luteum were seen laparoscopically. The mean (+/- sd) concentrations of progesterone in plasma in cows with and without a corpus luteum on their ovaries were 1.49 +/- 0.78 ng/ml (n = 31) and 0.14 +/- 0.09 ng/ml (n = 14), respectively. Plasma progesterone levels reflected age-dependent changes occurring in the cyclic corpus luteum. The accuracy of diagnosing ovarian contents was 82 and 91 per cent for rectal palpation and plasma progesterone levels respectively. Approximately 29 per cent follicles (larger than 10 mm) were incorrectly diagnosed as corpora lutea by rectal palpation.

A laparoscopic technique for in vivo observation of ovaries in the water buffalo (Bubalus bubalis)

A technique was developed for observing the ovaries of the water buffalo (Bubalus bubalis) restrained in a standing position using a laparoscope (10 mm diameter, 600 mm length) inserted in the right paralumbar fossa after sedation with xylazine and local infiltration anaesthesia. Insufflation of the abdominal cavity with carbon dioxide was necessary to pass the laparoscope along the body wall to the pelvic inlet where both ovaries could be examined in detail with a manipulating probe inserted ipsilaterally. Twenty-one buffaloes were subjected to 50 laparoscopic examinations without infections or adverse reactions. Laparoscopy was a simple, reliable and rapid technique for repeated observation of the ovaries in the buffalo.