Nicotinic modulation of Ca²⁺ oscillations in rat cortical neurons in vitro

Abstract

roles of nicotine on Ca 2ϩ oscillations [intracellular Ca 2ϩ ([Ca 2ϩ ]i) oscillation] in rat primary cultured cortical neurons were studied. The spontaneous [Ca 2ϩ ]i oscillations (SCO) were recorded in a portion of the neurons (65%) cultured for 7-10 days in vitro. Application of nicotine enhanced [Ca 2ϩ ]i oscillation frequency and amplitude, which were reduced by the selective ␣4␤2-nicotinic acetylcholine receptors (nAChRs) antagonist dihydro-␤-erythroidine (DH␤E) hydrobromide, and the selective ␣7-nAChRs antagonist methyllycaconitine citrate (MLA, 20 nM). DH␤E reduced SCO frequency and prevented the nicotinic increase in the frequency. DH␤E somewhat enhanced SCO amplitude and prevented nicotinic increase in the amplitude. MLA (20 nM) itself reduced SCO frequency without affecting the amplitude but blocked nicotinic increase in [Ca 2ϩ ]i oscillation frequency and amplitude. Furthermore, coadministration of both ␣ 4␤2-and ␣7-nAChRs antagonists completely prevented nicotinic increment in [Ca 2ϩ ]i oscillation frequency and amplitude. Thus, our results indicate that both ␣ 4␤2-and ␣7-nAChRs mediated nicotine-induced [Ca 2ϩ ]i oscillations, and two nAChR subtypes differentially regulated SCO. intracellular calcium ion concentration oscillations; nicotine; ␣4␤2-nicotinic acetylcholine receptors; ␣7-nicotinic acetylcholine receptors; calcium NICOTINIC ACETYLCHOLINE RECEPTORS (nAChRs) mediate the excitability of neuronal circuits related to the memory, motivation, and mood (15, 16), are reduced in neurodegenerative and neuropsychiatric disorders such as schizophrenia and Alzheimer's disease (6,22,24), and have been proposed as potential therapeutic targets for these diseases (13,28).At least four different nAChR subtypes, non-␣ 7 (␣ 2 , ␣ 3 ␤ 4 , ␣ 4 ␤ 2 )-and ␣ 7 -nAChRs, are expressed in the cortex. The most commonly expressed nAChR subtype is the ␣ 4 ␤ 2 -receptor (90%), which is characterized by its high affinity for acetylcholine (ACh) and nicotinic agonists (10,30 ] i oscillations are implicated in the regulation of neural plasticity (3, 26), which may be related to the increased efficiency and specificity of gene expression. Studies show both oscillation amplitude and frequency are critical for the regulation of gene expression and transcription (14,25).Although it has been reported that activation of nAChRs induces [Ca 2ϩ ] i oscillations, which is mediated by Ca 2ϩ influx and melatonin release from pinealocytes (17), the effect of nicotine on [Ca 2ϩ ] i oscillations in cortical neurons has not been reported. In this study, we investigated the nicotinic modulation of [Ca 2ϩ ] i oscillations in rat cortical neurons in primary culture and found that nicotinic enhancement of the oscillatory Ca 2ϩ signals is mediated through both ␣ 4 ␤ 2 -and ␣ 7 -nAChRs. MATERIALS AND METHODS Cortical neuronal cultures.Primary cultures of cortical neurons were prepared from 17-to 18-day-old Sprague-Dawley rat embryos as described previously (14a). All cell culture reagents were purchased from Invitrog...

Calcium imaging in intact mouse acinar cells in acute pancreas tissue slices

“…CCK-dependent recruitment of oscillating cells was also reported in pancreatic acinar cells in terms of receptor-mediated [Ca 2+ ] i mobilization [ 113 ]. On the other hand, amplitude modulation was observed in cortical neurons [ 114 ], and this mechanism is most probably not involved in acinar cells [ 105 ].…”

Involvement of alpha-7 nicotinic receptor (α7nAChR) in respiratory syncytial virus infection-induced asthma in rats

“…Moreover, the effects of α7nAChR silencing were promoted by NGF antibody or DXMS. nAChR subunits, primarily the α7nAChR has been reported to redistribute in asthmatic mice (14,15). Especially, α7nAChR was a potential therapeutic target for the treatment of ILC2s-dependent asthma (16).…”

“…The release of adrenaline from chroma n cells depends on the activation of calcium channels to produce su cient concentration of [Ca2+], whereas [Ca2+] mainly depends on the regulation of Ca2+ channels by subtypes of nAChR on chroma n cell membranes (15). Previous studies have con rmed that the Ca2+ permeability of different subtypes of nAChR is different (23)(24)(25).…”

“…Redistribution of nAChR subunits, primarily the α7nAChR, occurs in the adrenal medulla of asthmatic mice (14,15). A previous study reported that α7nAChR was a potential therapeutic target for the treatment of type-2 innate lymphoid cells (ILC2s)-dependent asthma (16).…”

Statement on the toxicological properties and maximum residue levels of acetamiprid and its metabolites

“… Rat primary cortical neurons differentiated for 12–14 days in vitro applied for evaluation of neuronal network formation (rNNF), neurite maturation, synaptogenesis, viability and high‐content imaging assay to screen for changes in neurite outgrowth (US EPA). However, published data suggest that primary rat cells from brain cortex, in vitro express α4β2‐nAChRs and α7‐nAChRs as measured for instance by the spontaneous [Ca 2+ ]i oscillations and nicotine‐induced [Ca 2+ ]i oscillations (Wang et al., 2016 ). Earlier studies also suggest that nAChR‐binding sites are present in rat primary neuronal cells in culture (Dávila‐García et al., 1999 ).…”