Differential modulation of electrical stimulation of periaqueductal gray and thalamus on nociceptive behaviors of rats / 生理学报

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.

Neurophysiological mechanisms and effects of emotional regulation on time perception / 生理学报

Time is an important element for cognitive processes. Timing and time perception have been investigated by neuroscientists and psychologists for many years. It is well accepted that emotions could alter our experience of time. Previous studies of the emotional modulation on temporal perception focus primarily on behavioral and psychological experiments. In recent years, studies about the neurophysiological mechanisms of time perception have made some progress. Therefore, researchers started to explore how emotions influence our sense of time on the aspects of neural networks, neurotransmitters and synaptic plasticity. In this paper, we tried to review current studies about the effects of emotional regulation on time perception and the relevant neurophysiological mechanisms. This review will help us to deeply understand the neural mechanisms of time perception.

Multiple analysis of the difference in intestinal absorption between the main components and the extract of Glycyrrhiza uralensis / 药学学报

The aim of this study is to investigate the rat intestinal absorption behavior of two main active components, liquiritin, glycyrrhizin and the extract of Glycyrrhiza uralensis. The rat intestinal perfusion model was employed. Concentrations of the compounds of the interest in the intestinal perfusate, bile and plasma samples were determined by HPLC and UPLC. At the same time, the intestinal enzymes incubation test and the partition coefficient determination, the absorption of liquiritin and glycyrrhizin alone and the extract were multiple analyzed. The results showed that the P(eff) (effective permeability) of liquiritin or glycyrrhizin alone or the extract was less than 0.3, which suggested their poor absorption in the intestine. The P(eff) of the two main active components or the extract was not significantly different in duodenum, jejunum, colon and ileum segment. The P(eff) of the glycyrrhizin in the extract had no significant difference in the four intestinal segments compared with the glycyrrhizin alone. The absorption of the liquiritin displayed significant difference (P < 0.05) at ileum segment compared with the liquiritin alone, while it had no markedly change in the other three segments. This phenomenon indicated that some ingredients in the extract might improve the absorption of liquiritin. Moreover, no parent compounds and their metabolites were found in the intestinal perfusate, bile and the plasma samples. The results demonstrated that the influence of the other ingredients in the extract on the two components might not increase the amount of liquiritin and glycyrrhizin in the bile and plasma within the duration of the test.

Democratic organization of the thalamocortical neural ensembles in nociceptive signal processing / 生理学报

Acute pain is a warning protective sensation for any impending harm. However, chronic pain syndromes are often resistant diseases that may consume large amount of health care costs. It has been suggested by recent studies that pain perception may be formed in central neural networks via large-scale coding processes, which involves sensory, affective, and cognitive dimensions. Many central areas are involved in these processes, including structures from the spinal cord, the brain stem, the limbic system, to the cortices. Thus, chronic painful diseases may be the result of some abnormal coding within this network. A thorough investigation of coding mechanism of pain within the central neuromatrix will bring us great insight into the mechanisms responsible for the development of chronic pain, hence leading to novel therapeutic interventions for pain management.