The pedunculopontine nucleus (PPN) is located in the dorso-lateral part of the ponto-mesencephalic tegmentum. The PPN is composed of two groups of neurons: one containing acetylcholine, and the other containing non-cholinergic neurotransmitters (GABA, glutamate). The PPN is connected reciprocally with the limbic system, the basal ganglia nuclei (globus pallidus, substantia nigra, subthalamic nucleus), and the brainstem reticular formation. The caudally directed corticolimbic-ventral striatal-ventral pallidal-PPN-pontomedullary reticular nuclei-spinal cord pathway seems to be involved in the initiation, acceleration, deceleration, and termination of locomotion. This pathway is under the control of the deep cerebellar and basal ganglia nuclei at the level of the PPN, particularly via potent inputs from the medial globus pallidus, substantia nigra pars reticulata and subthalamic nucleus. The PPN sends profuse ascending cholinergic efferent fibers to almost all the thalamic nuclei, to mediate phasic events in rapid-eye-movement sleep. Experimental evidence suggests that the PPN, along with other brain stem nuclei, is also involved in anti-nociception and startle reactions. In idiopathic Parkinson's disease (IPD) and parkinson plus syndrome, overactive pallidal and nigral inhibitory inputs to the PPN may cause sequential occurrences of PPN hypofunction, decreased excitatory PPN input to the substantia nigra, and aggravation of striatal dopamine deficiency. In addition, neuronal loss in the PPN itself may cause dopamine-r esistant parkinsonian deficits, including gait disorders, postural instability and sleep disturbances. In patients with IPD, such deficits may improve after posteroventral pallidotomy, but not after thalamotomy. One of the possible explanations for such differences is that dopamine-resistant parkinsonian deficits are mediated to the PPN by the descending pallido-PPN inhibitory fibers, which leave the pallido-thalamic pathways before they reach the thalamic targets.
Animal ; Basal Ganglia/cytology ; Human ; Mesencephalon/physiology* ; Mesencephalon/cytology ; Movement Disorders/etiology* ; Pons/physiology* ; Pons/cytology ; Thalamus/cytology

Sound duration plays important role in acoustic communication. Information of acoustic signal is mainly encoded in the amplitude and frequency spectrum of different durations. Duration selective neurons exist in the central auditory system including inferior colliculus (IC) of frog, bat, mouse and chinchilla, etc., and they are important in signal recognition and feature detection. Two generally accepted models, which are "coincidence detector model" and "anti-coincidence detector model", have been raised to explain the mechanism of neural selective responses to sound durations based on the study of IC neurons in bats. Although they are different in details, they both emphasize the importance of synaptic integration of excitatory and inhibitory inputs, and are able to explain the responses of most duration-selective neurons. However, both of the hypotheses need to be improved since other sound parameters, such as spectral pattern, amplitude and repetition rate, could affect the duration selectivity of the neurons. The dynamic changes of sound parameters are believed to enable the animal to effectively perform recognition of behavior related acoustic signals. Under free field sound stimulation, we analyzed the neural responses in the IC and auditory cortex of mouse and bat to sounds with different duration, frequency and amplitude, using intracellular or extracellular recording techniques. Based on our work and previous studies, this article reviews the properties of duration selectivity in central auditory system and discusses the mechanisms of duration selectivity and the effect of other sound parameters on the duration coding of auditory neurons.
Acoustic Stimulation ; Animals ; Auditory Perception ; physiology ; Echolocation ; physiology ; Evoked Potentials, Auditory ; physiology ; Humans ; Inferior Colliculi ; physiology ; Mesencephalon ; physiology ; Sound Localization ; physiology ; Time Perception ; physiology

OBJECTIVE: To establish an efficient protocol for directed differentiation of human induced pluripotent stem cells (hiPSCs) into functional midbrain dopaminergic progenitor cells (DAPs) in vitro. METHODS: hiPSCs were induced to differentiate into DAPs in two developmental stages. In the first stage (the first 13 days), hiPSCs were induced into intermediate cells morphologically similar to primitive neuroepithelial cells (NECs) in neural induction medium containing a combination of small molecule compounds. In the second stage, the intermediate cells were further induced in neural differentiation medium until day 28 to obtain DAPs. After CM-DiI staining, the induced DAPs were stereotactically transplanted into the right medial forebrain bundle (MFB) of rat models of Parkinson's disease (PD). Eight weeks after transplantation, the motor behaviors of PD rats was evaluated. Immunofluorescence assay of brain sections of the rats was performed at 2 weeks after transplantation to observe the survival, migration and differentiation of the transplanted cells in the host brain microenvironment. RESULTS: hiPSCs passaged stably on Matrigel showed a normal diploid karyotype, expressed the pluripotency markers OCT4, SOX2, and Nanog, and were positive for alkaline phosphatase. The primitive neuroepithelial cells obtained on day 13 formed dense cell colonies in the form of neural rosettes and expressed the neuroepithelial markers (SOX2, Nestin, and PAX6, 91.3%-92.8%). The DAPs on day 28 highly expressed the specific markers (TH, FOXA2, LMX1A and NURR1, 93.3-96.7%). In rat models of PD, the hiPSCs-DAPs survived and differentiated into TH⁺, FOXA2⁺ and Tuj1⁺ neurons at 2 weeks after transplantation. Eight weeks after transplantation, the motor function of PD rats was significantly improved as shown by water maze test (P < 0.0001) and apomorphine-induced rotation test (P < 0.0001) compared with rats receiving vehicle injection. CONCLUSION HiPSCs can be effectively induced to differentiate into DAPs capable of differentiating into functional neurons both in vivo and in vitro. In rat models of PD, the transplanted hiPSCs-DAPs can survive for more than 8 weeks in the MFB and differentiate into multiple functional neurocytes to ameliorate neurological deficits of the rats, suggesting the potential value of hiPSCs-DAPs transplantation for treatment of neurological diseases.
Humans ; Rats ; Animals ; Induced Pluripotent Stem Cells ; Cell Differentiation/physiology* ; Neurons ; Parkinson Disease ; Mesencephalon ; Cells, Cultured

Itch is an unpleasant sensation that provokes the desire to scratch. While acute itch serves as a protective system to warn the body of external irritating agents, chronic itch is a debilitating but poorly-treated clinical disease leading to repetitive scratching and skin lesions. However, the neural mechanisms underlying the pathophysiology of chronic itch remain mysterious. Here, we identified a cell type-dependent role of the anterior cingulate cortex (ACC) in controlling chronic itch-related excessive scratching behaviors in mice. Moreover, we delineated a neural circuit originating from excitatory neurons of the ACC to the ventral tegmental area (VTA) that was critically involved in chronic itch. Furthermore, we demonstrate that the ACC→VTA circuit also selectively modulated histaminergic acute itch. Finally, the ACC neurons were shown to predominantly innervate the non-dopaminergic neurons of the VTA. Taken together, our findings uncover a cortex-midbrain circuit for chronic itch-evoked scratching behaviors and shed novel insights on therapeutic intervention.
Mice ; Animals ; Gyrus Cinguli/physiology* ; Pruritus/pathology* ; Mesencephalon ; Cerebral Cortex/pathology* ; Neurons/pathology*

OBJECTIVETo observe the effect of oxysophoridine (OSR) on the EEG and its power spectrum of reticulum formation in mesencephalon of anaesthetized rat.

METHODUtilizing the technique of brain stereotactic apparatus, electrodes were implanted into reticulum formation of mesencephalon. Monopolar lead and computerized FFT technique were employed to record and analyse the index of EEG, power spectrum and frequency distribution in order to study the effect of oxysophoridine on the bioelectricity change of mesencephalon reticulum formation in rats.

RESULTAfter administrating(icy) with oxysophoridine at the dose of 2.5,5, 10 mg/rat, the EEG of mesencephalon reticulum formation mainly characterized with low amplitude and slow waves accompanied by spindle-formed sleeping waves with a significant decrease of total power of EEG (P < 0.05) while the ratio of theta, alpha waves increased in total frequency of rats (P < 0.05).

CONCLUSIONOxysophoridine possesses central inhibitory effects and its inhibitory mechanism may associate with the reduction of bioelectricity in mesencephalon reticulum formation. Mesencephalon reticulum formation may serve as one part of the structure serving as the circuit conducting the central inhibitory effect of oxysophoridine. [Key words] oxysophoridine; reticulum formation; electroencephalogram (EEG) ; rats

Alkaloids ; administration & dosage ; Animals ; Electroencephalography ; Male ; Mesencephalon ; drug effects ; physiology ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Reticular Formation ; drug effects ; physiology

The transplantation of dopaminergic neurons in the brain has been attempted in experimental animals and humans as the new treatment modality of Parkinson's disease. Before the trial of dopaminergic neuronal transplantation in human, the authors proceeded with the animal experiment of fetal dopaminergic cell transplantation in a rat Parkinson's disease model. The aims of this experiment were to confirm the availability of fetal mesencephalic cells as the donor, to compare the viability of cells according to different cell manipulation methods, and to follow up the functional recovery in the transplanted Parkinson's disease model. As a result, the authors concluded that the simple enzyme digestion method had a better cell survival rate than the multiple enzyme digestion method. Also, the transplanted mesencephalic cells could not only survive in the host animal but also promote functional recovery.
Animal ; Corpus Striatum/*physiology ; Dopamine/*metabolism ; *Fetal Tissue Transplantation ; Male ; Mesencephalon/cytology/*embryology/metabolism ; Neurons/metabolism/*transplantation ; Parkinson Disease/*surgery ; Rats ; Rats, Sprague-Dawley ; Support, Non-U.S. Gov't

To observe the influence of tumor necrosis factor-alpha (TNF-alpha) on differentiation of rat mesencephalic neural stem cells (NSCs), the numbers of neurons, astrocytes and oligodendrocytes generated from NSCs were analyzed after differentiation for 3 days by using immunocytochemistry technique. The results show that: (1) TNF-alpha enhanced the proportions of neurons and oligodendrocytes in progeny of NSCs; and (2) TNF-alpha induced the proliferation of oligodendrocytes derived from NSCs, but the proliferation of astrocytes was not influenced by TNF-alpha. We conclude that the TNF-alpha could influence the application of NSCs.
Animals ; Animals, Newborn ; Astrocytes ; cytology ; Cell Differentiation ; physiology ; Cell Proliferation ; Mesencephalon ; cytology ; Neural Stem Cells ; cytology ; Neurons ; cytology ; Oligodendroglia ; cytology ; Rats ; Rats, Sprague-Dawley ; Tumor Necrosis Factor-alpha ; physiology

The distribution of the nerve growth factor (NGF), the glial fibrillary acidic protein (GFAP) and the ciliary neurotrohic factor (CNTF) was performed in coronal sections of the mesencephalon, rhombencephalon and spinal cord in the developing Mongolian gerbils. Generally, NGF specifically recognizes neurons with the NGF receptor, whereas GFAP does the glia, and CNTF does the motor neurons. The receptor expression was examined separately in gerbils between embryonic days 15 (E15) and postnatal weeks 3 (PNW 3). The NGF-IR was first observed in the spinal cord at E21, which might be related to the maturation. The GFAP reactivity was peaked at the postnatal days 2 (PND2), while the highest CNTF-reaction was expressed at PNW 2. The GFAP stains were observed in the aqueduct and the spinal cord, which appeared to project laterally at E19. The CNTF was observed only after the birth and found in both the neurons and neuroglia of the substantia nigra, mesencephalon, cerebellum and the spinal cord from PND1 to PNW3. These results suggest that NGF, GFAP and CNTF are important for the development of the neurons and the neuroglia in the central nervous system at the late prenatal and postnatal stages.
Animals ; Brain Stem/enzymology/*metabolism ; Ciliary Neurotrophic Factor/*metabolism ; Embryonic and Fetal Development/physiology ; Female ; Gerbillinae/*embryology ; Glial Fibrillary Acidic Protein/*metabolism ; Immunohistochemistry/veterinary ; Mesencephalon/embryology/metabolism ; Nerve Growth Factor/*metabolism ; Pregnancy ; Rhombencephalon/embryology/metabolism ; Spinal Cord/embryology/*metabolism

In the experiment, we designed and synthesized two siRNAs based on the sequence of nuclear receptor-related factor 1 (Nurr1) mRNA. They were separately subcloned into the plasmid of pSilenCircle (pSC) containing U6 promoter. The pSC-Nurr1 vectors (pSC-N1 and pSC-N2) specific to Nurr1 gene and the negative control vector of short-hairpin RNA (shRNA) eukaryotic expression vector were constructed. We cultured the dopaminergic cell line MN9D and the verified vectors were transfected with LipofectamineTM 2000 in vitro. The positive cell clones transfected with pSC were obtained after being screened with 500 mug/ml G418. After that, the silencing effects of Nurr1 and TH mRNA or protein were detected by real time RT-PCR and Western blot. The neurite extension of MN9D cells was observed and photographed by inverted microscope. The results showed that Nurr1 mRNA expression in MN9D cells was specifically down-regulated by the vectors of pSC-N1 and pSC-N2, and the silencing effects were 62.3% and 45.6%, respectively. The dopaminergic phenotype of TH mRNA was also suppressed significantly and the silencing effects were 76.3% and 62.6%, respectively. Meanwhile, the expressions of Nurr1 and TH proteins were also significantly suppressed, and the silencing effects of Nurr1 and TH protein were 57.4%, 72.0% and 79.1%, 70.1% respectively. The negative control and liposome groups had no effect on the two genes. In conclusion, Nurr1 shRNA expressing vectors can inhibit the expressions of Nurr1 and TH mRNA or protein in MN9D cells, and Nurr1 might play a role in neurite extension of MN9D cells. Nurr1 shRNA expressing vector may provide a novel applicable strategy for the study on the function of the genes associated with Parkinson disease and the development of dopaminergic neuron.
Cell Line ; Dopaminergic Neurons ; cytology ; metabolism ; Down-Regulation ; Fetus ; Humans ; Mesencephalon ; cytology ; Neurites ; physiology ; Nuclear Receptor Subfamily 4, Group A, Member 2 ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; RNA, Small Interfering ; genetics ; Transfection ; Tyrosine 3-Monooxygenase ; genetics ; metabolism