Orthodontic tooth separation activates the hypothalamic area in the human brain

OBJECTIVES： An animal experiment clarified that insertion of an orthodontic apparatus activated the trigeminal neurons of the medulla oblongata. Orthodontic tooth movement is known to be associated with the sympathetic nervous system and controlled by the nucleus of the hypothalamus. However, the transmission of both has not been demonstrated in humans. The purpose of this study were to examine the activated cerebral areas using brain functional magnetic resonance imaging（MRI）, when orthodontic tooth separators were inserted, and to confirm the possibility of the transmission route from the medulla oblongata to the hypothalamus.METHODS： Two types of alternative orthodontic tooth separators（brass contact gauge and floss） were inserted into the right upper premolars of 10 healthy volunteers. Brain functional T2＊-weighted images and anatomical T1-weighted images were taken.RESULTS： The blood oxygenation level dependent（BOLD） signals following insertion of a brass contact gauge and floss significantly increased in the somatosensory association cortex and hypothalamic area.CONCLUSION： Our findings suggest the possibility of a transmission route from the medulla oblongata to the hypothalamus.

Lateral Hypothalamic Area Glutamatergic Neurons and Their Projections to the Lateral Habenula Modulate the Anesthetic Potency of Isoflurane in Mice

The lateral hypothalamic area(LHA)plays a pivotal role in regulating consciousness transition,in which orexinergic neurons,GABAergic neurons,and melanin-concentrating hormone neurons are involved.Glutamatergic neurons have a large population in the LHA,but their anesthesia-related effect has not been explored.Here,we found that genetic ablation of LHA glutamatergic neurons shortened the induction time and prolonged the recovery time of isoflurane anesthesia in mice.In contrast,chemogenetic activation of LHA glutamatergic neurons increased the time to anesthesia and decreased the time to recovery.Optogenetic activation of LHA glutamatergic neurons during the maintenance of anesthesia reduced the burst suppression pattern of the electroencephalogram(EEG)and shifted EEG features to an arousal pattern.Photostimulation of LHA glutamatergic projections to the lateral habenula(LHb)also facilitated the emergence from anesthesia and the transition of anesthesia depth to a lighter level.Collectively,LHA glutamatergic neurons and their projections to the LHb regulate anesthetic potency and EEG features.

Effect of Acupuncture on Monoamines and Adenosine Triphosphatase Activityin Lateral Hypothalamic Area of ObeseRats

Objective: To study the mechanism of acupuncture in treating simple obesity. Methods: Central nerve push-pull perfusion and biochemical technique were used to observe the effect of acupuncture on the obese parameters, changes of monoamine transmitters and activity of ATPase in the lateral hypothalamic area (LHA) of obese rats. Results: Noradrenaline (NA) level in LHA of obese rats was higher but serotonin (5-HT) level and ATPase activity were lower than those in normal rats. After acupuncture treatment, in the same time of reducing body weight, NA level in LHA of rats was reduced, and 5-HT level and ATPase activity in it were increased.(P<0.05 and P<0.01). Conclusion:The effective regulation on LHA of obese rats is possibly one of the key factors in anti-obesity effect of acupuncture.

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.