Synergistic Effects of Acetylcholine and Glutamate on the Release of Arachidonic Acid from Cultured Striatal Neurons

Abstract

The activation of muscarinic and NMDA receptors by carbachol and NMDA, respectively, stimulated the release of [3H]arachidonic acid ([3H]AA) from cultured striatal neurons. Striking synergistic effects were observed when both agonists were coapplied. This synergistic response was suppressed by atropine or (5R, 10S)‐(+)‐5‐methyl‐10,11‐dihydro‐5H‐dibenzo[a,d]cyclohepten‐5,10‐imine hydrogen maleate and inhibited by magnesium. It was markedly reduced in the absence of external calcium and suppressed by mepacrine. NMDA strongly elevated the intracellular calcium concentration ([Ca2+]i), but carbachol was ineffective. Ionomycin, α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate, or potassium depolarization, which increased [Ca2+]i but was ineffective on [3H]AA release, also potentiated the carbachol response. Sphingosine and Ro 31‐8220 suppressed the responses evoked by carbachol, NMDA, or both agonists. However, no synergistic responses could be observed when phorbol 12‐myristate 13‐acetate was associated with either carbachol or NMDA. Together, these results suggest that both the massive influx of calcium induced by NMDA and the coupling of muscarinic receptors with a putative phospholipase A2 are required for the strong synergistic effects of carbachol and NMDA on [3H]AA release. Synergistic effects were also observed with acetylcholine and glutamate in the presence of magnesium, further revealing the physiological relevance of this process.

Neurochemical and electrophysiological characteristics of rat striatal neurons in primary culture

“…Significant progress has been made in the study of neuronal polarity (Dotti and Banker, 1991), G protein-coupled receptors (Vilchis et al, 2002;Morris et al, 2000), ion channel physiology (Sucher et al, 2000;Parak et al, 2001;Centonze et al, 2002) and inhibitory synaptic transmission (Kowalski et al, 1995) by using primary neuronal culture. Striatal neurons maintained in primary culture have been employed to study physiology of the NMDA receptors (Popp et al, 1998), opioid receptors (Vaysse et al, 1990), metabotropic glutamate receptors (Paolillo et al, 1998), and acetylcholine receptors (Tence et al, 1995 These preparations are particularly well suited for gene-transfer studies intended to manipulate electrical activity, since transduced neurons can be identified in the living state by the use of fluorescent reporter genes and their electrophysiological properties may be studied individually by patch clamp methods (Falk et al, 2003). In order to better extrapolate the results to the in vivo state, it is necessary to characterize the properties of cultured neurons under the specific growth and maintenance conditions utilized (Kessler, 1986).…”

Costimulation of N -methyl- d -aspartate and muscarinic neuronal receptors modulates gap junctional communication in striatal astrocytes

“…Indeed, according to previous studies, AA is a potent inhibitor of astrocyte GJC (18)(19)(20). In addition, as shown in neuronal cultures from the mouse striatum, this unsaturated fatty acid is released after stimulation of NMDA receptors (27), and a synergistic response is observed under costimulation of NMDA and muscarinic receptors (15). Therefore, the evoked AA release was investigated in our different models of rat striatal cultures.…”

“…Because cultured astrocytes do not express N-methyl-D-asparte (NMDA) receptors (14), cocultures of neurons and astrocytes provide an appropriate model to address this question by selectively stimulating neurons. Interestingly, in striatal neurons, several biochemical and electrophysiological responses evoked by NMDA are enhanced by acetylcholine (Ach) through the stimulation of muscarinic receptors (15,16). This could partly account for the modulatory role of cholinergic interneurons on the activity of efferent striatal neurons (see ref.…”

Pathways of polyunsaturated fatty acid utilization: Implications for brain function in neuropsychiatric health and disease

“…Neurotransmitters affect PUFA turnover, as PLA 2 is activated by multiple receptor types--dopamine D 2 (Vial and Piomelli, 1995), serotonin 5-HT 2 (Berg et al, 1996), glutamate (Tence et al, 1995), and muscarinic acetylcholine (Jones et al, 1996)--to liberate fatty acids from the sn -2 position of phospholipids. In turn, PUFAs also regulate the activity, mRNA expression, and protein levels of multiple PLA 2 isoforms (Downes and Currie, 1998; Lister et al, 1988; Rao et al, 2007a).…”