No abstract available.
Goats* ; Mesencephalon* ; Periaqueductal Gray* ; Somatostatin*

The periaqueductal gray (PAG) is a complex mesencephalic structure involved in the integration and execution of active and passive self-protective behaviors against imminent threats, such as immobility or flight from a predator. PAG activity is also associated with the integration of responses against physical discomfort (e.g., anxiety, fear, pain, and disgust) which occurs prior an imminent attack, but also during withdrawal from drugs such as morphine and cocaine. The PAG sends and receives projections to and from other well-documented nuclei linked to the phenomenon of drug addiction including: (i) the ventral tegmental area; (ii) extended amygdala; (iii) medial prefrontal cortex; (iv) pontine nucleus; (v) bed nucleus of the stria terminalis; and (vi) hypothalamus. Preclinical models have suggested that the PAG contributes to the modulation of anxiety, fear, and nociception (all of which may produce physical discomfort) linked with chronic exposure to drugs of abuse. Withdrawal produced by the major pharmacological classes of drugs of abuse is mediated through actions that include participation of the PAG. In support of this, there is evidence of functional, pharmacological, molecular. And/or genetic alterations in the PAG during the impulsive/compulsive intake or withdrawal from a drug. Due to its small size, it is difficult to assess the anatomical participation of the PAG when using classical neuroimaging techniques, so its physiopathology in drug addiction has been underestimated and poorly documented. In this theoretical review, we discuss the involvement of the PAG in drug addiction mainly via its role as an integrator of responses to the physical discomfort associated with drug withdrawal.
Amygdala ; Humans ; Morphine ; Nociception ; Periaqueductal Gray ; Substance-Related Disorders

OBJECTIVE: The periaqueductal gray matter (PAG), a small midbrain structure, presents dysfunction in migraine. However, the precise neurological mechanism is still not well understood. Herein, the aim of this study was to investigate the texture characteristics of altered PAG in episodic migraine (EM) patients based on high resolution brain structural magnetic resonance (MR) images. MATERIALS AND METHODS: The brain structural MR images were obtained from 18 normal controls (NC), 18 EM patients and 16 chronic migraine (CM) patients using a 3T MR system. A PAG template was created using the International Consortium Brain Mapping 152 gray matter model, and the individual PAG segment was developed by applying the deformation field from the structural image segment to the PAG template. A grey level co-occurrence matrix was used to calculate the texture parameters including the angular second moment (ASM), contrast, correlation, inverse difference moment (IDM) and entropy. RESULTS: There was a significant difference for ASM, IDM and entropy in the EM group (998.629 ± 0.162 × 10−3, 999.311 ± 0.073 × 10−3, 916.354 ± 0.947 × 10−5) compared to that found in the NC group (998.760 ± 0.110 × 10−3, 999.358 ± 0.037 × 10−3 and 841.198 ± 0.575 × 10−5) (p < 0.05). The entropy was significantly lower among the patients with CM (864.116 ± 0.571 × 10−5) than that found among patients with EM (p < 0.05). The area under the receiver operating characteristic curve was 0.776 and 0.750 for ASM and entropy in the distinction of the EM from NC groups, respectively. ASM was negatively related to disease duration (DD) and the Migraine Disability Assessment Scale (MIDAS) scores in the EM group, and entropy was positively related to DD and MIDAS in the EM group (p < 0.05). CONCLUSION: The present study identified altered MR image texture characteristics of the PAG in EM. The identified texture characteristics could be considered as imaging biomarkers for EM.
Biomarkers ; Brain ; Brain Mapping ; Entropy ; Gray Matter ; Humans ; Magnetic Resonance Imaging ; Mesencephalon ; Migraine Disorders ; Periaqueductal Gray ; ROC Curve

Amygdalin is known as vitamain B17, and it was called laetrile. Amygdalin is composed of two molecules of glucose, one molecule of benzaldehyde which induces an analgesic action, and one molecule of hydrocyanic acid which is an anti-neoplastic compound. Amygdalin had been used to treat cancers and relieve pain. In order to evaluate whether the analgesic action of amygdalin is related with descending pain control system, we performed patch clamp study. In the present study, the modulatory effects of amygdalin on glycine- and glutamate-induced ion currents in periaqueductal gray (PAG) neurons were investigated using the nystatin-perforated patch clamp method. Continuous application of lipopolysaccharides (LPS) on PAG neurons resulted in increased glycine-induced ion current, and in decreased glutamate-induced ion current. In contrast, continuous application of amygdalin with LPS resulted in decreased glycine-induced ion current increased by LPS, and increased glutamate- induced ion current decreased by LPS in concentration- and time-dependent fashion. These results demonstrate that amygdalin modulates neuronal activity of PAG by modulation of glycine and glutamate. Based on the present results, it can be suggested that amygdalin participates in the regulation of the descending pain control system in the level of PAG neurons. The present study demonstrated that activation of the descending pain control system is one of the possible analgesic mechanisms of amygdalin.
Amygdalin ; Animals ; Benzaldehydes ; Cyclooxygenase 2 ; Glucose ; Glutamic Acid ; Glycine ; Hydrogen Cyanide ; Lipopolysaccharides ; Neurons ; Periaqueductal Gray ; Rats

We report a case of acute Wernicke encephalopathy in which diffusion-weighted imagings (DWI) revealed symmetrical high signal intensities in the medial thalamus, bilateral hemispheres of the cerebellum and periaqueductal gray matter. Calculation of the apparent diffusion coefficient demonstrated a mildly decreased diffusion on the affected regions. The high signal lesions were slowly resolved on the acute phase follow-up images with the administration of thimaine. We propose DWI should be included in the imaging protocols of patients suspected to suffer from Wernicke encephalopathy.
Cerebellum ; Diffusion* ; Follow-Up Studies ; Humans ; Magnetic Resonance Imaging* ; Periaqueductal Gray ; Thalamus ; Wernicke Encephalopathy*

OBJECTIVES: We attempted to compartmentalize the periaqueductal gray (PAG) of the rabbit in terms of the different distribution patterns between NADPH-diaphorase (NADPHd)- and calbindin D28K (CB)-positive neurons. METHODS: Immunohistochemistry and immunofluorescent labelling for CB and histochemistry for NADPHd were carried out on coronally-sectioned midbrain slices of the rabbit. RESULTS: NADPHd-positive neurons were selectively localized in the dorsolateral (DL), the middle one-third of the lateral (L), the dorsal half of the ventrolateral (VLd) PAG, and the supraoculomotor cap nucleus (Su3C). Clusters of CB-immunoreactive perikarya marked the dorsal half of DL (DLd), Su3C, the ventral one-third of L, and the ventral half of the ventrolateral (VLv) PAG. Double labelling for NADPHd and CB revealed that two markers labelled different neuronal groups in DLd and Su3C subdivisions. CONCLUSION: The present data suggest that NADPHd and CB can be regarded as reliable neurochemical markers to reveal the longitudinally-columnar organization within the PAG and to subdivide each columnar area.
Calcium-Binding Protein, Vitamin D-Dependent ; Immunohistochemistry ; Mesencephalon ; Neurons ; Periaqueductal Gray

Rodents exposed to a 15-min pretest swim in the forced swimming test (FST) exhibit prolonged immobility in a subsequent 5-min test swim, and antidepressant treatment before the test swim reduces immobility. At present, neuronal circuits recruited by antidepressant before the test swim remain unclear, and also less is known about whether antidepressants with different mechanisms of action could influence neural circuits differentially. To reveal the neural circuits associated with antidepressant effect in the FST, we injected desipramine or citalopram 0.5 h, 19 h, and 23 h after the pretest swim and observed changes in c-Fos expression in rats before the test swim, namely 24 h after the pretest swim. Desipramine treatment alone in the absence of pretest swim was without effect, whereas citalopram treatment alone significantly increased the number of c-Fos-like immunoreactive cells in the central nucleus of the amygdala and bed nucleus of the stria terminalis, where this pattern of increase appears to be maintained after the pretest swim. Both desipramine and citalopram treatment after the pretest swim significantly increased the number of c-Fos-like immunoreactive cells in the ventral lateral septum and ventrolateral periaqueductal gray before the test swim. These results suggest that citalopram may affect c-Fos expression in the central nucleus of the amygdala and bed nucleus of the stria terminalis distinctively and raise the possibility that upregulation of c-Fos in the ventral lateral septum and ventrolateral periaqueductal gray before the test swim may be one of the probable common mechanisms underlying antidepressant effect in the FST.
Amygdala ; Animals ; Antidepressive Agents ; Brain ; Citalopram ; Desipramine ; Neurons ; Periaqueductal Gray ; Rats ; Rodentia ; Swimming ; Up-Regulation

Pain is a multi-dimensional emotional experience, and pain sensation and pain emotion are the two main components. As for pain, previous studies only focused on a certain link of the pain transmission pathway or a certain key brain region, and there is a lack of evidence that connectivity of brain regions is involved in pain or pain regulation in the overall state. The establishment of new experimental tools and techniques has brought light to the study of neural pathways of pain sensation and pain emotion. In this paper, the structure and functional basis of the neural pathways involved in the formation of pain sensation and the regulation of pain emotion in the nervous system above the spinal cord level, including thalamus, amygdala, midbrain periaqueductal gray (PAG), parabrachial nucleus (PB) and medial prefrontal cortex (mPFC), are reviewed in recent years, providing clues for the in-depth study of pain.
Humans ; Pain ; Neural Pathways/physiology* ; Periaqueductal Gray/physiology* ; Brain ; Spinal Cord/physiology* ; Magnetic Resonance Imaging

A 41-year-old man was admitted due to altered mentality and confusion. He had showed progressive cerebellar ataxia, dysarthria, gait disturbance from his age of 33 years old. Brain MRI revealed high signal lesions in periaqueductal gray matter, mammillary bodies, median thalami and postcentral gyri bilaterally on T2-weighted images. Severe cerebellar atrophy was noted, too. We report a case of Wernicke's encephalopathy in a patient with probable multiple system atrophy. As far as we know, there have been no published report on this kind of case.
Adult ; Atrophy ; Brain ; Cerebellar Ataxia ; Dysarthria ; Gait ; Humans ; Magnetic Resonance Imaging ; Mamillary Bodies ; Multiple System Atrophy* ; Periaqueductal Gray ; Wernicke Encephalopathy*

Deep brain stimulation (DBS) is a surgical treatment which has shown remarkable therapeutic benefits for patients with a variety of neurologic conditions. As an important application, DBS has been used to treat intractable pain for over 60 years. Clinical studies have revealed that the selection of the stimulation sites depended on the types of pain. In this study, we selected ventrolateral periaqueductal gray (vlPAG) and ventral posterior lateral nucleus (VPL) as the target brain areas, which were widely used in clinical treatment of refractory pain, to clarify and compare the effects of vlPAG and VPL stimulation on different models of pain. Acute pain was evoked by thermal stimulation. The chronic inflammatory pain was produced by complete Freund's adjuvant (CFA) injection, while neuropathic pain was induced by spinal nerve ligation (SNL) surgery. Some important results emerged from this study: (1) in the experiment of normal rats, we found that unilateral vlPAG stimulation could lead to a significant increase of the thermal withdrawal threshold in bilateral hindpaws of rats, which means a significant bilateral analgesic action; (2) in the CFA test, both contralateral vlPAG and VPL stimulation significantly alleviated the thermal hyperalgesia, which exhibited analgesic effects to the chronic inflammatory pain; (3) in the SNL experiment, the results revealed that contralateral VPL stimulation could significantly abolish the mechanical allodynia induced by SNL, indicating remarkable analgesic effect to neuropathic pain. But the vlPAG stimulation did not have any effect on the mechanical allodynia. These results suggest that the electrical stimulation of the PAG works more effectively on nociceptive pain, including acute pain and chronic inflammatory pain. Besides, the VPL stimulation is much more sensitive for chronic pain, including chronic inflammatory pain and neuropathic pain.
Animals ; Behavior, Animal ; Chronic Pain ; Electric Stimulation ; Hyperalgesia ; Neuralgia ; Pain Measurement ; Periaqueductal Gray ; Rats ; Spinal Nerves ; Ventral Thalamic Nuclei