Identification of Morphine and Heroin-Treatment in Mice Using Metabonomics.

Although heroin and morphine are structural analogues and morphine is a metabolite of heroin, it is not known how the effect of each substance on metabolites in vivo differs. Heroin and morphine were administered to C57BL/6J mice in increasing doses from 2 to 25 and 3 to 9 mg kg-1 (twice a day, i.p.), respectively, for 20 days. The animals underwent withdrawal for 5 days and were readministered the drugs after 10 days. Serum and urine analytes were profiled using gas chromatography-mass spectrometry (GC-MS), and metabolic patterns were evaluated based on metabonomics data. Metabonomics data showed that heroin administration changed metabolic pattern, and heroin withdrawal did not quickly restore it to baseline levels. A relapse of heroin exposure changed metabolic pattern again. In contrast, although the administration of morphine changed metabolic pattern, whether from morphine withdrawal or relapse, metabolic pattern was similar to control levels. The analysis of metabolites showed that both heroin and morphine interfered with lipid metabolism, the tricarboxylic acid (TCA) cycle and amino acid metabolism. In addition, both heroin and morphine increased the levels of 3-hydroxybutyric acid and citric acid but decreased the serum levels of 2-ketoglutaric acid and tryptophan. Moreover, heroin and morphine reduced the levels of aconitic acid, cysteine, glycine, and oxalic acid in urine. The results show 3-Hydroxybutyric acid, tryptophan, citric acid and 2-ketoglutaric acid can be used as potential markers of opiate abuse in serum, while oxalic acid, aconitic acid, cysteine, and glycine can be used as potential markers in urine.

Reduced Neuronal cAMP in the Nucleus Accumbens Damages Blood-Brain Barrier Integrity and Promotes Stress Vulnerability.

BACKGROUND: Studies have suggested that chronic social stress specifically downregulates endothelial tight junction protein expression in the nucleus accumbens (NAc), thus increasing blood-brain barrier (BBB) permeability and promoting depression-like behaviors. However, the molecular mechanism underlying the reduction in tight junction protein, particularly in the NAc, is largely uncharacterized. METHODS: We performed comparative metabolomic profiling of the nucleus accumbens, prefrontal cortex, and hippocampus of social defeat-stressed mice to identify the molecular events that mediate BBB breakdown. RESULTS: We identified the levels of cyclic adenosine monophosphate (cAMP) that were specifically reduced in the NAc and positively correlated with the degree of social avoidance. Replenishing cAMP in the NAc was sufficient to improve BBB integrity and depression-like behaviors. We further found that cAMP levels were markedly decreased in neurons of the NAc, rather than in endothelial cells, astrocytes, or microglia. RNA-sequencing data showed that adenylate cyclase 5 (Adcy5), an enzyme responsible for the synthesis of cAMP from adenosine triphosphate (ATP), was predominantly expressed in the NAc; it also resided exclusively in neurons. Endogenous modulation of cAMP synthesis in neurons through the knockdown of Adcy5 in the NAc regulated the sensitivity to social stress. Moreover, deficient neuronal cAMP production in the NAc decreased the expression of reelin, while supplementary injection of exogenous reelin into the NAc promoted BBB integrity and ameliorated depression-like behaviors. CONCLUSIONS: Chronic social stress diminished cAMP synthesis in neurons, thus damaging BBB integrity in the NAc and promoting stress vulnerability. These results characterize neuron-produced cAMP in the NAc as a biological mechanism of neurovascular pathology in social stress.

pH-sensitive ZnO/carboxymethyl cellulose/chitosan bio-nanocomposite beads for colon-specific release of 5-fluorouracil.

To develop relatively green and ecofriendly smart vehicles for colon-specific drug delivery, carboxymethyl cellulose (CMC) and chitosan (CS) pH-sensitive biopolymers were used in this study. To overcome the weaknesses of CMC carriers, such as poor mechanical performance and an explosive drug release, zinc oxide (ZnO) nanoparticles were incorporated into CMC beads and then coated with a CS layer via a self-assembly technique to form core-shell polyelectrolyte complexes. An anticancer drug, 5-fluorouracil (5-FU), used as a model drug, was loaded into ZnO/CMC/CS bio-nanocomposite beads. Fourier transform infrared spectroscopy, scanning and transmission electron microscopy, and thermogravimetric analysis were used to characterize the chemical structure, morphological changes, and thermal properties of the developed drug carrier, respectively. By studying their swelling and in vitro 5-FU release profiles under simulated gastrointestinal conditions, the pH sensitivity of the developed bio-nanocomposite hydrogel beads could be investigated. The obtained beads with reduced porosity could effectively encapsulate 5-FU and showed self-sustained release behavior depending on the concentrations of CMC, CS, and ZnO nanoparticles. The developed beads also demonstrated a capacity for biodegradation. The results indicated that the ZnO/CMC/CS bio-nanocomposite beads exhibited pH-sensitivity and could be applied efficiently as biodegradable carriers for colon-specific 5-FU delivery.