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Molecular Neurobiology Jul 2022The role of damaging factors in the prenatal period as a basis for drug addiction in offspring is of great interest. In this study, we aim at deciphering the effects and...
The role of damaging factors in the prenatal period as a basis for drug addiction in offspring is of great interest. In this study, we aim at deciphering the effects and possible mechanisms of prenatal severe hypoxia (PSH) on predisposition to nicotine addiction in adult rats. In PSH rats, we found an increasing tendency to nicotine consumption in the two-bottle choice test. After 2 weeks of chronic treatment with nicotine via osmotic minipump (9 mg/kg per day), we assessed the symptoms of withdrawal in the conditioned place aversion test after mecamylamine (an antagonist of nicotinic acetylcholine receptors, nAChR) treatment. We showed that the mecamylamine-precipitated withdrawal aversion was stronger in the PSH group than in the control group. This suggests that PSH acts as a predisposing factor for developing nicotine addiction in adulthood. PSH rats also demonstrated an increased level of phosphorylated DARPP-32 protein (known as the relay for dopamine and glutamate signaling) at 34 threonine (pThr34DARPP-32) in relation to its total amount in the nucleus accumbens of the striatum (NAc). Meanwhile, no changes in both the content of dopamine in the mesolimbic pathway and the first type of dopamine receptors (DAR1) in NAc were found. The increased rate of DARPP-32 phosphorylation in adult PSH rats might result from excessive glutamatergic stimulation of the dopaminergic (DA) neurons of the ventral tegmental area (VTA) caused by activation of presynaptic nAChR by nicotine. This hypothesis is supported by the observed increase in VGluT2-positive terminals to Nurr1-positive neuronal bodies in VTA in PSH animals. Thus, the altered glutamate signaling phenotype might play a significant role in the development of PSH-related nicotine addiction.
Topics: Animals; Dopamine; Glutamic Acid; Hypoxia; Mecamylamine; Nicotine; Nicotinic Antagonists; Nucleus Accumbens; Rats; Rats, Wistar; Receptors, Nicotinic; Tobacco Use Disorder; Ventral Tegmental Area
PubMed: 35581520
DOI: 10.1007/s12035-022-02866-8 -
ELife May 2022Striatal spiny projection neurons (SPNs) transform convergent excitatory corticostriatal inputs into an inhibitory signal that shapes basal ganglia output. This process...
Striatal spiny projection neurons (SPNs) transform convergent excitatory corticostriatal inputs into an inhibitory signal that shapes basal ganglia output. This process is fine-tuned by striatal GABAergic interneurons (GINs), which receive overlapping cortical inputs and mediate rapid corticostriatal feedforward inhibition of SPNs. Adding another level of control, cholinergic interneurons (CINs), which are also vigorously activated by corticostriatal excitation, can disynaptically inhibit SPNs by activating α4β2 nicotinic acetylcholine receptors (nAChRs) on various GINs. Measurements of this disynaptic inhibitory pathway, however, indicate that it is too slow to compete with direct GIN-mediated feedforward inhibition. Moreover, functional nAChRs are also present on populations of GINs that respond only weakly to phasic activation of CINs, such as parvalbumin-positive fast-spiking interneurons (PV-FSIs), making the overall role of nAChRs in shaping striatal synaptic integration unclear. Using acute striatal slices from mice we show that upon synchronous optogenetic activation of corticostriatal projections blockade of α4β2 nAChRs shortened SPN spike latencies and increased postsynaptic depolarizations. The nAChR-dependent inhibition was mediated by downstream GABA release, and data suggest that the GABA source was not limited to GINs that respond strongly to phasic CIN activation. In particular, the observed decrease in spike latency caused by nAChR blockade was associated with a diminished frequency of spontaneous inhibitory postsynaptic currents in SPNs, a parallel hyperpolarization of PV-FSIs, and was occluded by pharmacologically preventing cortical activation of PV-FSIs. Taken together, we describe a role for tonic (as opposed to phasic) activation of nAChRs in striatal function. We conclude that tonic activation of nAChRs by CINs maintains a GABAergic brake on cortically-driven striatal output by 'priming' feedforward inhibition, a process that may shape SPN spike timing, striatal processing, and synaptic plasticity.
Topics: Animals; Cholinergic Agents; Corpus Striatum; Interneurons; Mice; Neurons; Nicotine; gamma-Aminobutyric Acid
PubMed: 35579422
DOI: 10.7554/eLife.75829 -
Addiction Biology May 2022Levamisole is a veterinary anthelmintic drug and a common adulterant of misused drugs. This study analyses the lethal, antinociceptive and haematological effects...
Levamisole is a veterinary anthelmintic drug and a common adulterant of misused drugs. This study analyses the lethal, antinociceptive and haematological effects produced by acute or repeated levamisole administration by itself or combined with morphine. Independent groups of male Swiss Webster mice were i.p. injected with 100 mg/kg morphine, 31.6 mg/kg levamisole (lethal doses at 10%, LD ) or the same doses combined. Naloxone pretreatment (10 mg/kg, i.p.) prevented morphine-induced death, as did 2.5 mg/kg, i.p. mecamylamine with levamisole. Co-administration of levamisole and morphine (Lvm + Mor) increased lethality from 10% to 80%. This augmented effect was prevented by 30 mg/kg, i.p. naloxone and reduced with 10 mg/kg naloxone plus 2.5 mg/kg, i.p. mecamylamine. In independent groups of mice, 17.7 mg/kg, i.p. levamisole antagonized the acute morphine's antinociceptive effect evaluated in the tail-flick test. Repeated 17.7 mg/kg levamisole administration (2×/day/3 weeks) did not affect tolerance development to morphine (10 mg/kg, 3×/day/1 week). Blood samples obtained from mice repeatedly treated with levamisole showed leukopenia and neutropenia. Morphine also produced neutropenia, increased erythrocyte count and other related parameters (e.g. haemoglobin). Lvm + Mor had similar effects on leukocyte and neutrophil counts to those seen with levamisole only, but no erythrocyte-related alterations were evident. Blood chemistry analysis did not indicate liver damage but suggested some degree of electrolyte balance impairment. In conclusion, Lvm + Mor increased death risk, altered morphine-induced antinociceptive effects and produced haematologic abnormalities. The importance of studying combinations of drugs of abuse lies in the fact that drug users frequently combine drugs, which are commonly adulterated.
Topics: Analgesics; Animals; Levamisole; Male; Mecamylamine; Mice; Morphine; Naloxone; Neutropenia
PubMed: 35470549
DOI: 10.1111/adb.13166 -
Neuropsychopharmacology Reports Jun 2022Cessation of smoking induces nicotine withdrawal symptoms such as anxiety, depression, and dysphoria, which could lead to smoking relapse. In the present study, we...
AIM
Cessation of smoking induces nicotine withdrawal symptoms such as anxiety, depression, and dysphoria, which could lead to smoking relapse. In the present study, we examined the role of noradrenergic transmission within the ventral bed nucleus of the stria terminalis (vBNST) on nicotine withdrawal-induced aversive behavior.
METHODS
Nicotine dependence in rats was established by subcutaneous implantation with a nicotine-filled osmotic minipump on day 1. Nicotine withdrawal was precipitated by administration of the nicotine receptor antagonist, mecamylamine (3.0 mg/kg, s.c.), on day 15. Nicotine withdrawal-induced intra-vBNST noradrenaline release and aversive behavior were examined by in vivo microdialysis and a conditioned place aversion (CPA) test, respectively.
RESULTS
Intra-vBNST noradrenaline release was significantly increased during nicotine withdrawal. Nicotine withdrawal induced aversive behavior, which was attenuated by intra-vBNST injection of the β-adrenoceptor antagonist, timolol.
CONCLUSIONS
These results suggest that enhanced noradrenergic transmission via β-adrenoceptors in the vBNST plays a crucial role in nicotine withdrawal-induced aversive behavior.
Topics: Animals; Nicotine; Norepinephrine; Rats; Rats, Sprague-Dawley; Septal Nuclei; Substance Withdrawal Syndrome
PubMed: 35437943
DOI: 10.1002/npr2.12252 -
Frontiers in Cellular Neuroscience 2022Activation of nicotinic acetylcholine receptors (nAChRs) expressed by innate immune cells can attenuate pro-inflammatory responses. Silent nAChR agonists, which...
Activation of nicotinic acetylcholine receptors (nAChRs) expressed by innate immune cells can attenuate pro-inflammatory responses. Silent nAChR agonists, which down-modulate inflammation but have little or no ionotropic activity, are of outstanding clinical interest for the prevention and therapy of numerous inflammatory diseases. Here, we compare two silent nAChR agonists, phosphocholine, which is known to interact with nAChR subunits α7, α9, and α10, and CF3-N,N-diethyl-'-phenyl-piperazine (CF3-diEPP), a previously identified α7 nAChR silent agonist, regarding their anti-inflammatory properties and their effects on ionotropic nAChR functions. The lipopolysaccharide (LPS)-induced release of interleukin (IL)-6 by primary murine macrophages was inhibited by CF3-diEPP, while phosphocholine was ineffective presumably because of instability. In human whole blood cultures CF3-diEPP inhibited the LPS-induced secretion of IL-6, TNF-α and IL-1β. The ATP-mediated release of IL-1β by LPS-primed human peripheral blood mononuclear leukocytes, monocytic THP-1 cells and THP-1-derived M1-like macrophages was reduced by both phosphocholine and femtomolar concentrations of CF3-diEPP. These effects were sensitive to mecamylamine and to conopeptides RgIA4 and [V11L; V16D]ArIB, suggesting the involvement of nAChR subunits α7, α9 and/or α10. In two-electrode voltage-clamp measurements CF3-diEPP functioned as a partial agonist and a strong desensitizer of classical human α9 and α9α10 nAChRs. Interestingly, CF3-diEPP was more effective as an ionotropic agonist at these nAChRs than at α7 nAChR. In conclusion, phosphocholine and CF3-diEPP are potent agonists at unconventional nAChRs expressed by monocytic and macrophage-like cells. CF3-diEPP inhibits the LPS-induced release of pro-inflammatory cytokines, while phosphocholine is ineffective. However, both agonists signal nAChR subunits α7, α9 and/or α10 to efficiently down-modulate the ATP-induced release of IL-1β. Compared to phosphocholine, CF3-diEPP is expected to have better pharmacological properties. Thus, low concentrations of CF3-diEPP may be a therapeutic option for the treatment of inflammatory diseases including trauma-induced sterile inflammation.
PubMed: 35431807
DOI: 10.3389/fncel.2022.779081 -
Phytomedicine : International Journal... Jun 2022Sinomenine (SIN) is an anti-inflammatory drug that has been used for decades in China to treat arthritis. In a previous study, SIN acted on α7 nicotinic acetylcholine...
BACKGROUND
Sinomenine (SIN) is an anti-inflammatory drug that has been used for decades in China to treat arthritis. In a previous study, SIN acted on α7 nicotinic acetylcholine receptor (α7nAChR) to inhibit inflammatory responses in macrophages, which indicates a new anti-inflammatory mechanism of SIN. However, the level of α7nAChR was increased in the inflammatory responses and was downregulated by SIN in vitro, so the underlying mechanisms of SIN acting on α7nAChR remain unclear.
PURPOSE
To analyze the role of α7nAChR in inflammation and the effect and mechanism of SIN regulation of α7nAChR.
METHODS
The effects of SIN on α7nAChR in endotoxemic mice and LPS-stimulated macrophages were observed. Nicotine (Nic) was used as a positive control, and berberine (Ber) was used as a negative control targeting α7nAChR. The antagonists of α7nAChR, α-bungarotoxin (BTX) and mecamylamine (Me), were used to block α7nAChR. In RAW264.7 macrophage cells in vitro, α7nAChR short hairpin RNA (shRNA) was used to knock down α7nAChR. Macrophage polarization was analyzed by the detection of TNF-α, IL-6, iNOS, IL-10, Arg-1, and Fizz1. U0126 was used to block ERK phosphorylation. The cytokines α7nAChR, ERK1/2, p-ERK1/2 and Egr-1 were detected.
RESULTS
SIN decreased the levels of TNF-α, IL-6 and the expression of α7nAChR increased by LPS in endotoxemic mice. The above effects of SIN were attenuated by BTX. In the α7nAChR shRNA transfected RAW264.7 cells, compared with the control, α7nAChR was knocked down, and M1 phenotype markers (including TNF-α, IL-6, and iNOS) were significantly downregulated, whereas M2 phenotype markers (including IL-10, Arg-1, and Fizz1) were significantly upregulated when stimulated by LPS. SIN inhibited the expression of p-ERK1/2 and the transcription factor Egr-1 induced by LPS in RAW264.7 cells, and the above effects of SIN were attenuated by BTX. The expression of α7nAChR was suppressed by U0126, which lessened the expression of p-ERK1/2 and Egr-1.
CONCLUSIONS
SIN acts on α7nAChR to inhibit inflammatory responses and downregulates high expression of α7nAChR in vivo and in vitro. The increase of α7nAChR expression is correlated with inflammatory responses and participates in macrophage M1 polarization. SIN downregulates α7nAChR via a feedback pathway of α7nAChR/ERK/Egr-1, which contributes to inhibiting macrophage M1 polarization and inflammatory responses.
Topics: Animals; Anti-Inflammatory Agents; Feedback; Interleukin-10; Interleukin-6; Lipopolysaccharides; Macrophages; Mice; Morphinans; RNA, Small Interfering; Tumor Necrosis Factor-alpha; alpha7 Nicotinic Acetylcholine Receptor
PubMed: 35397284
DOI: 10.1016/j.phymed.2022.154050 -
Journal of Insect Physiology 2022Dorsal unpaired median (DUM) neurons, are a class of insect neurosecretory cells, which are involved in the control of several functions, such as excretion and...
Dorsal unpaired median (DUM) neurons, are a class of insect neurosecretory cells, which are involved in the control of several functions, such as excretion and reproduction, or the release of neurohormones. Previous studies demonstrated that they express different nicotinic acetylcholine receptor subtypes, in particular α-bungarotoxin-insensitive receptors, with nAChR1 and nAChR2 subtypes. Here, we demonstrated that pulse application of 1 mM nicotine (300 ms pulse duration) induced inward currents which were reduced under bath application of 15 µM calmidazolium, a calmodulin inhibitor. Bath application of 0.5 µM α-bungarotoxin had no effect on calmidazolium action, suggesting that it could have an indirect effect through α-bungarotoxin-insensitive receptors. Indeed, nicotine-evoked currents were reduced by 10 µM d-tubocurarine, and completely blocked by 5 µM mecamylamine, which affected nAChR1 and nAChR2 subtypes, respectively. Our results demonstrated that nAChR2 subtypes are involved in the indirect effect of calmidazolium. Moreover, we found that this calmidazolium effect was associated to a strong reduction in intracellular calcium levels after pulse application of 1 mM nicotine. Thus, compared to previous studies on mammalian cells, calmidazolium did not cause an increase in intracellular calcium levels in DUM neurons, suggesting that different calcium mechanisms are involved in the calmidazolium effect.
Topics: Animals; Bungarotoxins; Calcium; Cockroaches; Imidazoles; Insecta; Mammals; Nicotine
PubMed: 35315336
DOI: 10.1016/j.jinsphys.2022.104385 -
Human Psychopharmacology Sep 2022Older women are at increased risk of developing Alzheimer's disease compared to men. One proposed reason is that following menopause there is a decline in estrogens....
OBJECTIVE
Older women are at increased risk of developing Alzheimer's disease compared to men. One proposed reason is that following menopause there is a decline in estrogens. Estrogens are important for cholinergic functioning and attenuate the impact of cholinergic antagonists on cognitive performance in postmenopausal women. Self-reported or subjective cognitive complaints in middle or older age may represent a harbinger of cognitive decline and those who endorse cognitive complaints appear more likely to develop future cognitive impairment. However, the response of individuals with cognitive complaints after menopause to estrogen and the relationship to cholinergic functioning has not been investigated. This study investigated the effect of estrogen treatment using 17β-estradiol on cognitive performance following anticholinergic blockade in postmenopausal women and the relationship of this interaction with the level of self-reported (subjective) postmenopausal cognitive complaints.
METHODS
Forty postmenopausal women (aged 50-60 years) completed a 3-month treatment regimen of either 1 mg oral estradiol or placebo. Participants then completed four challenge days in which they completed cognitive and behavioral tasks after one of four cholinergic antagonist drug conditions (oral mecamylamine (MECA), intravenous scopolamine, combined MECA and scopolamine, or PLC).
RESULTS
Compared to PLC, the estradiol treated group performed worse on attention tasks under cholinergic challenge including the choice reaction time task and the critical flicker fusion task. In addition, participants who endorsed greater cognitive complaints showed reduced performance on the N-back working memory task, regardless of whether they received estradiol treatment.
CONCLUSIONS
The findings of this study indicate that estradiol treatment was unable to mitigate anticholinergic blockade in postmenopausal women with subjective cognitive complaints, and worsened performance on attention tasks. Moreover, the present study suggests that greater levels of cognitive complaints following menopause may be associated with an underlying decline in cholinergic function that may manifest as an inability to compensate during working memory tasks.
Topics: Aged; Cholinergic Agents; Cholinergic Antagonists; Cognition; Estradiol; Estrogens; Female; Humans; Postmenopause; Scopolamine; Self Report
PubMed: 35212023
DOI: 10.1002/hup.2838 -
BMC Complementary Medicine and Therapies Jan 2022Rubus occidentalis, also known as black raspberry, contains several bioactive components that vary depending on the maturity of the fruit. The goal of this study was to...
BACKGROUND
Rubus occidentalis, also known as black raspberry, contains several bioactive components that vary depending on the maturity of the fruit. The goal of this study was to evaluate the efficacy of immature Rubus occidentalis extract(iROE) on acid-induced hyperalgesia, investigate the mechanism involved, and compare the antihyperalgesic effect of immature and mature ROEs.
METHODS
In adult male Sprague-Dawley rats, chronic muscle pain was induced via two injections of acidic saline into one gastrocnemius muscle. To evaluate the dose response, the rats were injected intraperitoneally with 0.9% saline or iROE (10, 30, 100, or 300 mg/kg) following hyperalgesia development. To evaluate the mechanism underlying iROE-induced analgesia, the rats were injected intraperitoneally with saline, yohimbine 2 mg/kg, dexmedetomidine 50 μg/kg, prazosin 1 mg/kg, atropine 5 mg/kg, mecamylamine 1 mg/kg, or naloxone 5 mg/kg 24 h after hyperalgesia development, followed by iROE 300 mg/kg administration. To compare immature versus mature ROE, the rats were injected with mature ROE 300 mg/kg and immature ROE 300 mg/kg after hyperalgesia development. For all experiments, the mechanical withdrawal threshold(MWT) was evaluated using von Frey filaments before the first acidic saline injection, 24 h after the second injection, and at various time points after drug administration. Data were analysed using multivariate analysis of variance(MANOVA) and the linear mixed-effects model(LMEM). We compared the MWT at each time point using analysis of variance with the Bonferroni correction.
RESULTS
The iROE 300 mg/kg injection resulted in a significant increase in MWT compared with the control, iROE 30 mg/kg, and iROE 100 mg/kg injections at ipsilateral and contralateral sites. The iROE injection together with yohimbine, mecamylamine, or naloxone significantly decreased the MWT compared with iROE alone, whereas ROE together with dexmedetomidine significantly increased the MWT. According to MANOVA, the effects of immature and mature ROEs were not significantly different; however, the LMEM presented a significant difference between the two groups.
CONCLUSIONS
Immature R. occidentalis showed antihyperalgesic activity against acid-induced chronic muscle pain, which may be mediated by the α-adrenergic, nicotinic cholinergic, and opioid receptors. The iROE displayed superior tendency regarding analgesic effect compared to mature ROE.
Topics: Animals; Behavior, Animal; Hyperalgesia; Male; Musculoskeletal Pain; Phytotherapy; Plant Preparations; Plant Senescence; Rats; Rats, Sprague-Dawley; Rubus; Saline Solution
PubMed: 35016667
DOI: 10.1186/s12906-021-03491-z -
Neuroscience Letters Jan 2022Psychological stress has been demonstrated to increase reports of pain in humans with pelvic pain of urologic origin. In rodent models, conditioning with acute footshock...
Psychological stress has been demonstrated to increase reports of pain in humans with pelvic pain of urologic origin. In rodent models, conditioning with acute footshock (AFS) has been demonstrated to increase measures of stress/anxiety as well as bladder hypersensitivity. The spinal neurochemical mechanisms of this pro-nociceptive process are unknown and so the present study administered antagonists for multiple receptors that have been associated with facilitatory mechanisms into the spinal intrathecal space. Bladder hypersensitivity was induced through use of an AFS paradigm in which female Sprague-Dawley rats received a 15-min intermittent shock treatment. Visceromotor responses (VMRs; abdominal muscle contractions) to air pressure-controlled urinary bladder distension (UBD) were used as nociceptive endpoints. Immediately following AFS treatments, rats were anesthetized (inhaled isoflurane, IP urethane) and surgically prepared. Pharmacological antagonists were administered via an intrathecal (IT) catheter onto the lumbosacral spinal cord and VMRs to graded UBD determined 15 min later. Administration of IT naloxone hydrochloride (10 μg) and IT phentolamine hydrochloride (10 μg) resulted in VMRs that were more robust than VMRs in rats that received AFS and IT normal saline whereas there was no significant effect of these drugs on VMRs in rats which underwent non-footshock procedures. In contrast, a low dose of the NMDA-receptor antagonist, MK-801 (30 μg), significantly reduced VMRs in rats made hypersensitive to UBD by AFS, but had no significant effect on rats that underwent non-footshock procedures. This study suggests that pro-nociceptive effects of AFS in otherwise healthy rats involve a spinal NMDA-linked mechanism. The effects of IT naloxone and IT phentolamine suggest the presence of inhibitory influences that are opioidergic and/or alpha-adrenergic and that are masked by the pro-nociceptive mechanisms. Other agents with no statistically significant effect on VMRs include methysergide (30 μg), ondansetron (10 μg), mecamylamine (50 μg), antalarmin (24 μg), aSVG30 (12 μg), and SSR149415 (50 μg).
Topics: Animals; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Female; Hyperalgesia; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Spinal Cord; Stress, Physiological; Urinary Bladder
PubMed: 34929317
DOI: 10.1016/j.neulet.2021.136401