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The central medial nucleus (CM), a prominent cell group of the intralaminar nuclei (ILN) of the thalamus, and the ventrolateral periaqueductal gray matter (vlPAG) are two major components of the medial pain system. Whether vlPAG and CM are input sources of nociceptive information to the basolateral amygdala (BLA) and whether they are involved in neuropathic pain regulation remain unclear. Clarifying the hierarchical organization of these subcortical nuclei (vlPAG, CM, and BLA) can enhance our understanding on the neural circuits for pain regulation. Behavioral test results showed that a CM lesion made by kainic acid (KA) injection could effectively alleviate mechanical hyperalgesia 4, 6, and 8 days after spared nerve injury (SNI) surgery, with the symptoms returning after 10 days. Morphological studies revealed that: (1) the CM received afferents from vlPAG and sent efferents to BLA, indicating that an indirect vlPAG–CM–BLA pathway exists; (2) such CM–BLA projections were primarily excitatory glutamatergic neurons as revealed by fluorescence in situ hybridization; (3) the fibers originated from the CM-formed close contacts with both excitatory and inhibitory neurons in the BLA; and (4) BLA-projecting CM neurons expressed Fos induced by SNI and formed close contacts with fibers from vlPAG, suggesting that the vlPAG–CM–BLA indirect pathway was activated in neuropathic pain conditions. Finally, the vlPAG–CM–BLA indirect pathway was further confirmed using anterograde and monosynaptic virus tracing investigation. In summary, our present results provide behavioral and morphological evidence that the indirect vlPAG–CM–BLA pathway might be a novel pain pathway involved in neuropathic pain regulation.

By taking the public welfare forest land in Jiangshan City of Zhejiang Province as the research object, based on the measured data of fixed sample plots and sublot of public welfare forest, the water conservation capacity and value of litter layer and soil layer in different forest stands were quantitatively measured and analyzed. The results showed that the effective interception amount of litter in different forest types of public welfare forest in Jiangshan City was coniferous and broad-leaved mixed forest>broad-leaved forest>Chinese fir forest>pine forest>moso bamboo forest. In the same depth of soil layer, the difference of soil physical properties and water holding capacity was not obvious. The soil layer contributed more than 99 % of the water conservation quantity of forest land. The order of water conservation ability was coniferous and broad-leaved mixed forest>broad-leaved forest>moso bamboo forest> Chinese fir forest>coniferous mixed forest>pine forest>shrub forest. The total annual water conservation quantity of public welfare forests in the whole city was 18 7,7869 million tons, with the value quantity of 1.979 billion yuan. The water conservation quantity per unit area was about 2813 t ⋅ hm-2, and the value quantity per unit area was about 29,700 yuan ⋅ hm-2. In Jiangshan City, the water conservation capacity of public welfare forest was stronger in the east, while the water conservation capacity of public welfare forest in the north was relatively weak. [ABSTRACT FROM AUTHOR]

The dorsal medial prefrontal cortex (dmPFC) has been recognized as a key cortical area for nociceptive modulation. However, the underlying neural pathway and the function of specific cell types remain largely unclear. Here, we show that lesions in the dmPFC induced an algesic and anxious state. Using multiple tracing methods including a rabies-based transsynaptic tracing method, we outlined an excitatory descending neural pathway from the dmPFC to the ventrolateral periaqueductal gray (vlPAG). Specific activation of the dmPFC/vlPAG neural pathway by optogenetic manipulation produced analgesic and antianxiety effects in a mouse model of chronic pain. Inhibitory neurons in the dmPFC were specifically activated using a chemogenetic approach, which logically produced an algesic and anxious state under both normal and chronic pain conditions. Antagonists of the GABAA receptor (GABAAR) or mGluR1 were applied to the dmPFC, which produced analgesic and antianxiety effects. In summary, the results of our study suggest that the dmPFC/vlPAG neural pathway might participate in the maintenance of pain thresholds and antianxiety behaviors under normal conditions, while silencing or suppressing the dmPFC/vlPAG pathway might be involved in the initial stages and maintenance of chronic pain and the emergence of anxiety-like behaviors. [ABSTRACT FROM AUTHOR]

Objective: Paraventricular thalamic nucleus (PVT) belongs to the midline nuclei of thalamus, whose function has attracted more and more attention. It has been reported that PVT is involved in a series of activities, such as fear, anxiety, feeding behavior and drug-seeking. Recent study has demonstrated that the PVT is implicated in acute visceral pain response, but it is unclear whether the PVT plays a critical role in central processing of chronic pain. Methods: Here, an integrative approach of behavioral tests, electrophysiology, and immunohistochemistry was used to advance the novel concept that the activation of the posterior portion of the PVT (pPVT)-central nucleus of amygdala (CeA) pathway causes facilitatory effect on neuropathic pain processing. Results: We first identified the parabrachial nucleus (PBN)- pPVT-central nucleus of amygdala (CeA) pathway, a brain stemthalamus- limbic system, is important for nociceptive transmission and modulation on the supraspinal level. Lesion or inhibition of pPVT neurons alleviated the mechanical allodynia induced by spared nerve injury (SNI). The excitability of pPVTS-CeA projection neurons were significantly increased in SNI rats. Importantly, selective optogenetic activation of the pPVT-CeA pathway induced obvious mechanical allodynia in naïve rats. In addition, we used rabies virus-based and cell-type-specific retrograde transsynaptic tracing techniques to define a novel neuronal circuit, in which the glutamatergic neurons in the vlPAG were the target of the pPVT-CeA descending projection facilitating pathway. Conclusion: Our data suggest that this pPVT-CeA-vlPAG circuit mediates central mechanisms of the descending pain facilitation underlying persistent pain conditions. [ABSTRACT FROM AUTHOR]