Engineering the Staple Oil Crop Brassica napus Enriched with α-Linolenic Acid Using the Perilla FAD2-FAD3 Fusion Gene

Modern people generally suffer from α-linolenic acid (ALA) deficiency, since most staple food oils are low in ALA content. Thus, the enhancement of ALA in staple oil crops is of importance. In this study, the FAD2 and FAD3 coding regions from the ALA-king species Perilla frutescens were fused using a newly designed double linker LP4-2A, driven by a seed-specific promoter P_NAP, and engineered into a rapeseed elite cultivar ZS10 with canola quality background. The mean ALA content in the seed oil of P_NAP:PfFAD2-PfFAD3 (N23) T5 lines was 3.34-fold that of the control (32.08 vs 9.59%), with the best line being up to 37.47%. There are no significant side effects of the engineered constructs on the background traits including oil content. In fatty acid biosynthesis pathways, the expression levels of structural genes as well as regulatory genes were significantly upregulated in N23 lines. On the other hand, the expression levels of genes encoding the positive regulators of flavonoid-proanthocyanidin biosynthesis but negative regulators of oil accumulation were significantly downregulated. Surprisingly, the ALA level in PfFAD2-PfFAD3 transgenic rapeseed lines driven by the constitutive promoter P_D35S was not increased or even showed a slight decrease due to the lower level of foreign gene expression and downregulation of the endogenous orthologous genes BnFAD2 and BnFAD3.

Growth factor for therapeutic angiogenesis in ischemic heart disease: A meta-analysis of randomized controlled trials

Aim: This study was designed to systematically evaluate the effects of growth factor (GF) for therapeutic angiogenesis on ischemic heart disease (IHD) by pooling the results of randomized controlled trials (RCTs). Methods and Results: PubMed, EMBASE, and CENTRAL databases were searched from inception to October 2022. RCTs, investigating the effects of GF therapy on IHD, were included. The risk bias of included study was assessed according to Cochrane tool. Weighted mean difference (WMD), calculated with fixed effect model or random effect model, was used to evaluate the effects of GF therapy on left ventricular ejection fraction (LVEF) and Canadian Cardiovascular Society (CCS) angina class. Relative risk (RR) was used to evaluate the effects of GF therapy on all-cause mortality, major adverse cardiovascular events (MACE) and revascularization. Meta-analysis, meta-regression analysis and publication bias analysis were performed by RevMan 5.3 or Stata 15.1 software. Twenty-nine studies involving 2899 IHD patients (1,577 patients in GF group and 1,322 patients in control group) were included. Compared with the control group, GF therapy did not reduce all-cause mortality (RR: 0.82; 95% CI: 0.54-1.24; p = 0.341), MACE [(RR: 0.83; 95% CI: 0.61-1.12; p = 0.227), revascularization (RR: 1.27, 95% CI: 0.82-1.96, p = 0.290) and CCS angina class (WMD: -0.08, 95% CI: -0.36 to 0.20, p = 0.560). However, GF therapy could increase LVEF during short-term follow-up (<1 year). Conclusion: GF for therapeutic angiogenesis was beneficial for increasing LVEF during short-term follow-up (<1 year), however, the therapy was not efficacious in decreasing all-cause mortality, MACE and revascularization.

Sciatic nerve block downregulates the BDNF pathway to alleviate the neonatal incision-induced exaggeration of incisional pain via decreasing microglial activation

Sciatic nerve block is under investigation as a possible therapeutic strategy for neonatal injury-induced exaggeration of pain responses to reinjury. Spinal microglial priming, brain-derived neurotrophic factor (BDNF) and Src homology-2 domain-containing protein tyrosine phosphatase-2 (SHP2) participate in exaggerated incisional pain induced by neonatal incision. However, effects of sciatic nerve block on exacerbated incisional pain and underlying mechanisms remain unclear. Here, we demonstrated that sciatic nerve block alleviates pain hypersensitivity and microglial activation in rats subjected to neonatal incision and adult incision (nIN-IN). Chemogenetic activation or inhibition of spinal microglia attenuates or mimics effects of sciatic nerve block on pain hypersensitivity, respectively. Moreover, α-amino-3-hydroxy- 5-methy- 4-isoxazole propionate (AMPA) receptor subunit GluA1 contributes to the exaggeration of incisional pain. The inhibition of BDNF or SHP2 blocks upregulations of downstream molecules in nIN-IN rats. Knockdown of SHP2 attenuates the increase of GluA1 induced by injection of BDNF in adult rats with only neonatal incision. The inhibition of microglia or ablation of microglial BDNF attenuates upregulations of SHP2 and GluA1. Additionally, sciatic nerve block downregulates the expression of these three molecules. Upregulation of BDNF, SHP2 or AMPA receptor attenuates sciatic nerve block-induced reductions of downstream molecules and pain hypersensitivity. Microglial activation abrogates reductions of these three molecules induced by sciatic nerve block. These results suggest that decreased activation of spinal microglia contributes to beneficial effects of sciatic nerve block on the neonatal incision-induced exaggeration of incisional pain via downregulating BDNF/SHP2/GluA1-containing AMPA receptor signaling. Thus, sciatic nerve block may be a promising therapy.

Development of a CRISPR-SaCas9 system for projection- and function-specific gene editing in the rat brain

A genome editing technique based on the clustered regularly interspaced short palindromic repeats (CRISPR)-associated endonuclease Cas9 enables efficient modification of genes in various cell types, including neurons. However, neuronal ensembles even in the same brain region are not anatomically or functionally uniform but divide into distinct subpopulations. Such heterogeneity requires gene editing in specific neuronal populations. We developed a CRISPR-SaCas9 system-based technique, and its combined application with anterograde/retrograde AAV vectors and activity-dependent cell-labeling techniques achieved projection- and function-specific gene editing in the rat brain. As a proof-of-principle application, we knocked down the cbp (CREB-binding protein), a sample target gene, in specific neuronal subpopulations in the medial prefrontal cortex, and demonstrated the significance of the projection- and function-specific CRISPR-SaCas9 system in revealing neuronal and circuit basis of memory. The high efficiency and specificity of our projection- and function-specific CRISPR-SaCas9 system could be widely applied in neural circuitry studies.

Increased expression of CaV3.2 T-type calcium channels in damaged DRG neurons contributes to neuropathic pain in rats with spared nerve injury

Ion channels are very important in the peripheral sensitization in neuropathic pain. Our present study aims to investigate the possible contribution of Ca_V3.2 T-type calcium channels in damaged dorsal root ganglion neurons in neuropathic pain. We established a neuropathic pain model of rats with spared nerve injury. In these model rats, it was easy to distinguish damaged dorsal root ganglion neurons (of tibial nerve and common peroneal nerve) from intact dorsal root ganglion neurons (of sural nerves). Our results showed that Ca_V3.2 protein expression increased in medium-sized neurons from the damaged dorsal root ganglions but not in the intact ones. With whole cell patch clamp recording technique, it was found that after-depolarizing amplitudes of the damaged medium-sized dorsal root ganglion neurons increased significantly at membrane potentials of −85 mV and −95 mV. These results indicate a functional up-regulation of Ca_V3.2 T-type calcium channels in the damaged medium-sized neurons after spared nerve injury. Behaviorally, blockade of Ca_V3.2 with antisense oligodeoxynucleotides could significantly reverse mechanical allodynia. These results suggest that Ca_V3.2 T-type calcium channels in damaged medium-sized dorsal root ganglion neurons might contribute to neuropathic pain after peripheral nerve injury.

BDNF contributes to the neonatal incision-induced facilitation of spinal long-term potentiation and the exacerbation of incisional pain in adult rats

Neonatal surgical injury exacerbates spinal microglial reactivity, modifies spinal synaptic function, leading to exaggerated pain hypersensitivity after adult repeated incision. Whether and how the alteration in microglial reactivity and synaptic plasticity are functionally related remain unclear. Previously, we and others have documented that spinal brain-derived neurotrophic factor (BDNF), secreted from microglia, contributes to long-term potentiation (LTP) in adult rodents with neuropathic pain. Here, we demonstrated that the mRNA and protein expression of spinal BDNF are significantly upregulated in adult rats subjected to neonatal incision and adult repeated incision (nIN-IN). Neonatal incision facilitates spinal LTP induced by BDNF or high frequency electrical stimulation after adult incision, including a decreased induction threshold and an increased magnitude of LTP. Coincidently, inhibition of spinal BDNF abrogates the LTP facilitation, alleviates the mechanical allodynia and thermal hyperalgesia in nIN-IN rats. By contrast, spinal application of exogenous BDNF in the adult rats with a single neonatal incision mimics the LTP facilitation and pain hypersensitivity, which have been found in nIN-IN rats. Exogenous BDNF-induced exacerbation of pain hypersensitivity could be blocked by BDNF inhibitor. In addition, blockade of microglial reactivity by intrathecal application of minocycline attenuates the elevation of BDNF and the LTP facilitation, and also, alleviates pain hypersensitivity in nIN-IN rats. In conclusion, spinal BDNF, at least partly derived from microglia, contributes to the neonatal incision-induced facilitation of spinal LTP and to the exacerbation of incisional pain in adult rats. Thus, spinal BDNF may combine the changes of microglial reactivity and synaptic plasticity in nIN-IN rats.

Accumulation of Cav3.2 T-type Calcium Channels in the Uninjured Sural Nerve Contributes to Neuropathic Pain in Rats with Spared Nerve Injury

Injuries to peripheral nerve fibers induce neuropathic pain. But the involvement of adjacent uninjured fibers to pain is not fully understood. The present study aims to investigate the possible contribution of Ca_v3.2 T-type calcium channels in uninjured afferent nerve fibers to neuropathic pain in rats with spared nerve injury (SNI). Aβ-, Aδ- and C-fibers of the uninjured sural nerve were sensitized revealed by in vivo single-unit recording, which were accompanied by accumulation of Ca_v3.2 T-type calcium channel proteins shown by Western blotting. Application of mibefradil, a T-type calcium channel blocker, to sural nerve receptive fields increased mechanical thresholds of Aβ-, Aδ- and C-fibers, confirming the functional involvement of accumulated channels in the sural nerve in SNI rats. Finally, perineural application of mibefradil or TTA-P2 to the uninjured sural nerve alleviated mechanical allodynia in SNI rats. These results suggest that axonal accumulation of Ca_v3.2 T-type calcium channels plays an important role in the uninjured sural nerve sensitization and contributes to neuropathic pain.

Reduced GABAergic transmission in the ventrobasal thalamus contributes to thermal hyperalgesia in chronic inflammatory pain

The ventrobasal (VB) thalamus is innervated by GABAergic afferents from the thalamic reticular nucleus (TRN) and participates in nociception. But how the TRN-VB pathway regulates pain is not fully understood. In the present study, we reported decreased extracellular GABA levels in the VB of rats with CFA-induced chronic inflammatory pain, measured by microdialysis with HPLC analysis. In vitro whole-cell patch-clamp recording showed decreased amplitudes of tonic currents, increased frequencies of mIPSCs, and increased paired-pulse ratios in thalamic slices from chronic inflammatory rats (7 days). Microinjection of the GABA_AR agonist muscimol and optogenetic activation of the TRN-VB pathway relieved thermal hyperalgesia in chronic inflammatory pain. By contrast, microinjecting the extrasynaptic GABA_AR agonist THIP or selective knockout of synaptic GABA_AR γ2 subunits aggravated thermal hyperalgesia in the chronic stage of inflammatory pain. Our findings indicate that reduced GABAergic transmission in the VB contributes to thermal hyperalgesia in chronic inflammatory pain, which could be a synaptic target for pharmacotherapy.

Exacerbation of tonic but not phasic pain by entorhinal cortex lesions

The hippocampus is actively involved in pain modulation. Previous studies have shown that inhibition, resection or pharmacological interference of the hippocampus or its subcortical afferent sources such as the medial septum and amygdala produce anti-nociceptive effects. But how the cortical connections of the hippocampus modulate pain remains unexplored. The entorhinal cortex (EC) constitutes the major gateway between the hippocampus and the neocortex. In the present study, rats with medial (MEC), lateral (LEC) or sham EC lesions and received the hot plate and the intra-plantar formalin injection tests. Neither MEC nor LEC lesions affected the hot plate test and the first phase of the formalin test. In contrast, paw licking responses in the second phase of the formalin test significantly increased with both MEC and LEC lesions. These results suggested that that the hippocampal-cortical interactions channeled by the EC were involved in tonic but not phasic pain conditions, and that cortical and sub-cortical connections of the hippocampus played independent roles in pain modulation.

Lysine-specific demethylase 1 in breast cancer cells contributes to the production of endogenous formaldehyde in the metastatic bone cancer pain model of rats

Background

Bone cancer pain seriously affects the quality of life of cancer patients. Our previous study found that endogenous formaldehyde was produced by cancer cells metastasized into bone marrows and played an important role in bone cancer pain. However, the mechanism of production of this endogenous formaldehyde by metastatic cancer cells was unknown in bone cancer pain rats. Lysine-specific demethylase 1 (LSD1) is one of the major enzymes catalyzing the production of formaldehyde. The expression of LSD1 and the concentration of formaldehyde were up-regulated in many high-risk tumors.

Objective

This study aimed to investigate whether LSD1 in metastasized MRMT-1 breast cancer cells in bone marrows participated in the production of endogenous formaldehyde in bone cancer pain rats.

Methodology/Principal Findings

Concentration of the endogenous formaldehyde was measured by high performance liquid chromatography (HPLC). Endogenous formaldehyde dramatically increased in cultured MRMT-1 breast cancer cells in vitro, in bone marrows and sera of bone cancer pain rats, in tumor tissues and sera of MRMT-1 subcutaneous vaccination model rats in vivo. Formaldehyde at a concentration as low as the above measured (3 mM) induced pain behaviors in normal rats. The expression of LSD1 which mainly located in nuclei of cancer cells significantly increased in bone marrows of bone cancer pain rats from 14 d to 21 d after inoculation. Furthermore, inhibition of LSD1 decreased the production of formaldehyde in MRMT-1 cells in vitro. Intraperitoneal injection of LSD1 inhibitor pargyline from 3 d to 14 d after inoculation of MRMT-1 cancer cells reduced bone cancer pain behaviors.

Conclusion

Our data in the present study, combing our previous report, suggested that in the endogenous formaldehyde-induced pain in bone cancer pain rats, LSD1 in metastasized cancer cells contributed to the production of the endogenous formaldehyde.

Role of the spinal cord NR2B-containing NMDA receptors in the development of neuropathic pain

Activation of N-methyl-d-aspartate (NMDA) receptors in the spinal dorsal horn has been shown to be essential for the initiation of central sensitization and the hyperexcitability of dorsal horn neurons in chronic pain. However, whether the spinal NR2B-containing NMDA (NMDA-2B) receptors are involved still remains largely unclear. Using behavioral test and in vivo extracellular electrophysiological recording in L5 spinal nerve-ligated (SNL) neuropathic rats, we investigate the roles of spinal cord NMDA-2B receptors in the development of neuropathic pain. Our study showed that intrathecal (i.t.) injection of Ro 25-6981, a selective NMDA-2B receptor antagonist, had a dose-dependent anti-allodynic effect without causing motor dysfunction. Furthermore, i.t. application of another NMDA-2B receptor antagonist ifenprodil prior to SNL also significantly inhibited the mechanical allodynia but not the thermal hyperalgesia. These data suggest that NMDA-2B receptors at the spinal cord level play an important role in the development of neuropathic pain, especially at the early stage following nerve injury. In addition, spinal administration of Ro 25-6981 not only had a dose-dependent inhibitory effect on the C-fiber responses of dorsal horn wide dynamic range (WDR) neurons in both normal and SNL rats, but also significantly inhibited the long-term potentiation (LTP) in the C-fiber responses of WDR neurons induced by high-frequency stimulation (HFS) applied to the sciatic nerve. These results indicate that activation of the dorsal horn NMDA-2B receptors may be crucial for the spinal nociceptive synaptic transmission and for the development of long-lasting spinal hyperexcitability following nerve injury. In conclusion, the spinal cord NMDA-2B receptors play a role in the development of central sensitization and neuropathic pain via the induction of LTP in dorsal horn nociceptive synaptic transmission. Therefore, the spinal cord NMDA-2B receptor is likely to be a target for clinical pain therapy.