Stimulating GABAergic Neurons in the Nucleus Accumbens Core Alters the Trigeminal Neuropathic Pain Responses in a Rat Model of Infraorbital Nerve Injury

The nucleus accumbens core (NAcc) is an important component of brain reward circuitry, but studies have revealed its involvement in pain circuitry also. However, its effect on trigeminal neuralgia (TN) and the mechanism underlying it are yet to be fully understood. Therefore, this study aimed to examine the outcomes of optogenetic stimulation of NAcc GABAergic neurons in an animal model of TN. Animals were allocated into TN, sham, and control groups. TN was generated by infraorbital nerve constriction and the optogenetic virus was injected into the NAcc. In vivo extracellular recordings were acquired from the ventral posteromedial nucleus of the thalamus. Alterations of behavioral responses during stimulation “ON” and “OFF” conditions were evaluated. In vivo microdialysis was performed in the NAcc of TN and sham animals. During optogenetic stimulation, electrophysiological recordings revealed a reduction of both tonic and burst firing activity in TN animals, and significantly improved behavioral responses were observed as well. Microdialysis coupled with liquid chromatography/tandem mass spectrometry analysis revealed significant alterations in extracellular concentration levels of GABA, glutamate, acetylcholine, dopamine, and citrulline in NAcc upon optic stimulation. In fine, our results suggested that NAcc stimulation could modulate the transmission of trigeminal pain signals in the TN animal model.     

Effects of modified atmosphere packaging conditions on quality preservation of powdered infant formula

The effect of different modified atmospheres (100% N₂, 100% CO₂, 70% N₂/30% CO₂, 50% N₂/50% CO₂, and air) on the quality preservation of powdered infant formula was investigated by a storage test at 30°C. Metal can packages of 400 g per unit were stored for 493 days with periodic measurements of package gas composition and product quality attributes, which included peroxide value (POV), pH, titratable acidity, bifidobacteria count, hydroxymethylfurfural content, surface colour, and solubility. In the air package, POV as an oxidative quality index increased highly along with oxygen concentration decrease, reaching a maximum of 58.7 meq/kg lipid at 350 days. Compared with the air package, POV increase of the product was significantly lower, with all the O₂‐excluded modified atmosphere packages showing a maximum of 28.5 to 29.3 meq/kg at 350 days. Packages of high CO₂ concentration experienced a pH decrease and an acidity increase of the stored product caused by dissolution of CO₂. The count of bifidobacteria in the product was maintained higher after 119 days in the package of 100% CO₂ than in the other packages. Hydroxymethylfurfural content showed a slight increase after an initial period of slight decrease, with little difference among the package treatments. There were no significant changes in product solubility and surface colour during storage. Considering that the high CO₂ atmosphere helps the survival of bifidobacteria and protects the product from oxidation without negative effects on the other quality attributes, it is suggested for use in packaging of powdered infant formula.