Effects of Subchronic Aluminum Exposure on Amino Acids Neurotransmitters in Chicken Brain

To investigate the effects of aluminium （Al） exposure on amino acid neurotransmitters, the chickens with different levels of subchronic Al poisoning were estabolished by continuous peritoneal injection of fixed volume and different concentrations of gradient of aluminium trichloride （AlCl3）. The levels of amino acid neurotransmitters in chicken brains were determined by high performance liquid chromatography （HPLC） after being exposed of Al for 60 days, and Al levels in serum and brain tissue were determined by atomic absorption spectrophotometry （AAS）. The results showed that Glu levels increased with the increase of Al, but there was no significant difference compared with the control. The levels of Al, Asp, Gly, GABA and Tau were significantly higher in Al-treated groups than those in the control. The results indicated that Al intoxication led to excitatory neurotoxicity.

Relationship Between the Central Hypotensive Effect of Acupuncture or Melatonin and the Changes of Medullary Amino Acid Neurotransmitter

To investigate whether changes of amino acid neurotransmitter releases in the rostral ventrolateral medulla （rVLM） were related to acupuncture and to the antihypertensive effect of melatonin （Mel） microinjected into the anterior hypothalamic area （AHA） of rats with stress-induced hypertension （SIH）, as well as to compare and analyze the relationship between the both antihypertensive mechanisms of acupuncture and of Mel in the AHA. Methods： Animal model of SIHR was made by electric foot shocks combined with noises. Electroacupuncture （EA） was used and “Zusanli” acupoint of both side was selected. The technique of drug microinjection into the brain was used to observe the change of blood pressure （BP）, and synchronously, brain microdialysis was performed for collecting dialysate samples, and then the concentration of amino acid neurotransmitters in the dialysate samples was determined by high performance liquid chromatography combined with fluorescent detection （HPLC-FD）. Results： After the animal received stress treatment, the BP elevated, synchronously, the release of glutamate （Glu） in the rVLM increased, and when EA was performed, the elevated BP of the rats with SIH decreased, simultaneously, the release of Glu in the rVLM decreased also. After Mel was microinjected of into the AHA of the SIHR, the elevated BP attenuated, meanwhile, the release of Glu decreased, and those of γ-aminobutyric acid （GABA） and taurine （Tau） increased in the rVLM.Administration of bicuculline, an antagonist of GABAA receptor, into the rVLMprior to microinjection of Mel imo the AHA could partially block the depressor effect of Mel in the AHA. Conclusion： The decrease in the release of Glu in the rVLM contributes to the antihypertensive effect of both acupuncture and Mel in the AHA in the rats with SIH, and the increase in the release of GABA and Tau in the rVLM is also im0ortam to Mel in the AHA.

Mechanism of the Reversal Effect of Acupuncture on the Fall of Blood Pressure Induced by Angiotensin-(1-7)in the Caudal Ventrolateral Medulla of Rats

Objective：To investigate the mechanism of the reversal effect of acupuncture on the fall of blood pressure induced by angiotensin （1-7）[Ang-（1 7）] in the caudal ventrolateral medulla （CVLM） of rats. Methods： Ang-（1-7） and its selective receptor antagonist （DAla7）, Ang（1-7） and Ang（779） were microinjected into the CVLM respectively to induce the change of blood pressure, during which, the concentrations of amino acid neurotransmitters were detected by means of microdialysis and high performance liquid chromatography （HPLC）combined with fluorescent detector, on the other hand, the effects of electro-acupuncture （EA） on the level of blood pressure and the concentrations of amino acid neurotransmitters were also observed. Results： Unilateral microinjection of Ang（1 7） into the CVLM could decrease the blood pressure （BP）, which was accompanied by an increase in the release of Glu and a decrease in the release of Tau in the same site; Whereas microinjection of Ang-779 into the CVLM could elevate BP, which was accompanied by a decrease in the release of Glu and an increase in the release of Tau; EA at acupoint Zusanli （ST 36） for 20 min could inhibit the fall of blood pressure induced by microinjection of Ang-（1-7） into the CVLM and the elevation of blood pressure induced by microinjection of Ang-779 into the CVLM, and in the meantime, it could inhibit the changes of the release of Glu and Tau induced by microinjection of Ang-（1-7） and Ang-779 into the CVLM. Conclusion： The reversal effect of EA on the fall or elevation of blood pressure induced by microinjection of Ang-（1-7） or Ang-779 into the CVLM might be related to the changes of Glu and Tau release.