TY - JOUR
T1 - Inhibitory pathways and the inhibition of luteinizing hormone-releasing hormone release by alcohol
AU - Lomniczi, Alejandro
AU - Mastronardi, Claudio A.
AU - Faletti, Alicia G.
AU - Seilicovich, Adriana
AU - De Laurentiis, Andrea
AU - McCann, Samuel M.
AU - Rettori, Valeria
PY - 2000/2/29
Y1 - 2000/2/29
N2 - In this research we examined the mechanisms by which ethanol (EtOH) inhibits luteinizing hormone-releasing hormone (LHRH) release from incubated medial basal hypothalamic explants. EtOH (100 mM) stimulated the release of two inhibitory neurotransmitters: γ-aminobutyric acid (GABA) and γ- endorphin. EtOH also inhibited NO production, indicative of a suppression of nitric oxide synthase (NOS) activity. This inhibition was reversed by naltroxone (10-8 M), a μ-opioid receptor blocker, indicating that the inhibition of NOS by EtOH is mediated by β-endorphin. EtOH also blocked N- methyl-D-aspartic acid-induced LHRH release, but the blockade could not be reversed by either the GABA receptor blocker, bicuculline (10-5 M), naltroxone (10-8 M), or both inhibitors added together. However, increasing the concentration of naltrexone (10-6 M) but not bicuculline (10-4 M) reversed the inhibition. When we lowered the concentration of EtOH (50 mM), the EtOH-induced blockade of LHRH release could be reversed by either bicuculline (10-5 M), naltroxone (10-8 M), or the combination of the two blockers. Therefore, GABA is partially responsible for the blockade of N- methyl-D-aspartic acid-induced LHRH release. The block by GABA was exerted by inhibiting the activation of cyclooxygenase by NO, because it was reversed by prostaglandin E2, the product of activation of cyclooxygenase. Because the inhibition caused by the higher concentration of EtOH could not be reduced by bicuculline (10-4 M) but was blocked by naltroxone (10-6 M), the action of alcohol can be accounted for by stimulation of β-endorphin neurons that inhibit LHRH release by inhibition of activation of NOS and stimulation of GABA release.
AB - In this research we examined the mechanisms by which ethanol (EtOH) inhibits luteinizing hormone-releasing hormone (LHRH) release from incubated medial basal hypothalamic explants. EtOH (100 mM) stimulated the release of two inhibitory neurotransmitters: γ-aminobutyric acid (GABA) and γ- endorphin. EtOH also inhibited NO production, indicative of a suppression of nitric oxide synthase (NOS) activity. This inhibition was reversed by naltroxone (10-8 M), a μ-opioid receptor blocker, indicating that the inhibition of NOS by EtOH is mediated by β-endorphin. EtOH also blocked N- methyl-D-aspartic acid-induced LHRH release, but the blockade could not be reversed by either the GABA receptor blocker, bicuculline (10-5 M), naltroxone (10-8 M), or both inhibitors added together. However, increasing the concentration of naltrexone (10-6 M) but not bicuculline (10-4 M) reversed the inhibition. When we lowered the concentration of EtOH (50 mM), the EtOH-induced blockade of LHRH release could be reversed by either bicuculline (10-5 M), naltroxone (10-8 M), or the combination of the two blockers. Therefore, GABA is partially responsible for the blockade of N- methyl-D-aspartic acid-induced LHRH release. The block by GABA was exerted by inhibiting the activation of cyclooxygenase by NO, because it was reversed by prostaglandin E2, the product of activation of cyclooxygenase. Because the inhibition caused by the higher concentration of EtOH could not be reduced by bicuculline (10-4 M) but was blocked by naltroxone (10-6 M), the action of alcohol can be accounted for by stimulation of β-endorphin neurons that inhibit LHRH release by inhibition of activation of NOS and stimulation of GABA release.
KW - Bicuculline
KW - Cyclooxygenase
KW - Naltrexone
KW - Nitric oxide synthase
KW - Prostaglandin E
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U2 - 10.1073/pnas.040569597
DO - 10.1073/pnas.040569597
M3 - Article
C2 - 10688896
AN - SCOPUS:0034104289
SN - 0027-8424
VL - 97
SP - 2337
EP - 2342
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 5
ER -