Acute Ethanol Administration Differentially Alters Enkephalinase and Aminopeptidase N Activity and mRNA Levels in Regions of the Nigrostriatal Pathway

Abstract

Opioid peptides play a key role in ethanol reinforcement and may also represent important determinants in brain sensitivity to ethanol through modulation of nigrostriatal dopaminergic activity. Regulation of opioid levels by peptidase-degrading enzymes could be relevant in ethanol's actions. The aim of this work was to study the acute ethanol (2.5 g/kg) effects on the activity and mRNA expression of enkephalinase (NEP) and aminopeptidase N (APN) in the rat substantia nigra (SN) and the anterior-medial (amCP) and medial-posterior (mpCP) regions of the caudate-putamen (CP). Enzymatic activities were measured by fluorometric assays and mRNA expression by reverse transcriptase polymerase chain reaction. Acute ethanol administration differentially altered peptidase activities and mRNA expression with different kinetics. Ethanol increased and decreased NEP mRNA levels in the SN and amCP, respectively, but produced biphasic effects in the mpCP. APN mRNA levels were increased by ethanol in all brain regions. Ethanol induced a transient and long-lasting increase in NEP (mpCP) and APN (amCP) activities, respectively. Peptidase activities were not changed by ethanol in the SN. Our results indicate that striatal NEP and APN are important ethanol targets. Ethanol-induced changes in these neuropeptidases in the CP could contribute to the mechanisms involved in brain sensitivity to ethanol.

Synaptic plasticity mediating cocaine relapse requires matrix metalloproteinases

“…35 cycles was selected following optimization experiments performed prior to mRNA measurement indicating that 35 cycles resulted in levels of product formation that remained in the linear range for each set of primers and thus was suitable for semi-quantitative RT-PCR (data not shown). The following primers were used 25 , MMP2 forward 5′-GATCTGCAAGCAAGACATTGTCTT-3′ MMP2 reverse 5′-GCCAAATAAACCGATCCTTGAA-3′ MMP9 forward 5′-GTAACCCTGGTCACCGGACTT-3′ MMP9 reverse 5′-ATACGTTCCCGGCTGATCAG TIMP-2 forward 5′-AGGGAAGGCGGAAGGAGAT-3′ TIMP-2 reverse 5′-CCAGGGCACAATAAAGTCACAGA-3′ TIMP-3 forward 5′-AGCATCAGCAATGCCACAGA-3′ and Cyclophilin forward 5′-GGGGAGAAAGGATTTGGCTA-3′ Cyclophilin reverse 5′-ACATGCTTGCCATCCAGCC-3′ 26 . PCR reactions were separated by 1.5% agarose gel electrophoresis and densitometry values were determined using Fiji (imagej Version 1.47) software.…”

Computer‐aided (in silico) approaches in the mode‐of‐action analysis and safety assessment of Ostarine and 4‐methylamphetamine

“…The ethanol‐induced increase in APN expression has been found to be long lasting in the NAc and amCP (Morales‐Mulia et al ., ). However, the exact mechanism of this has not been determined (Morales‐Mulia et al ., ). Carbonic anhydrase catalyzes the conversion of water and carbon dioxide into bicarbonate, and the clinical significance of the subtypes of this enzyme is still unclear (Barnett et al ., ).…”

“…In addition, in a study carried out by Morales‐Mulia et al . (), it was shown that acute ethanol administration increases the level of APN mRNA in both the anterior‐medial (amCP) and medial‐posterior caudate‐putamen. The ethanol‐induced increase in APN expression has been found to be long lasting in the NAc and amCP (Morales‐Mulia et al ., ).…”

“…(), it was shown that acute ethanol administration increases the level of APN mRNA in both the anterior‐medial (amCP) and medial‐posterior caudate‐putamen. The ethanol‐induced increase in APN expression has been found to be long lasting in the NAc and amCP (Morales‐Mulia et al ., ). However, the exact mechanism of this has not been determined (Morales‐Mulia et al ., ).…”

Striatal enkephalinergic differences in rats selectively bred for intrinsic running capacity

“…Midbrain dopaminergic transmission sensitizes the striatum to rewarding stimuli, mediates the incentive salience associated with these stimuli (Berridge and Robinson, 1998; Ikemoto, 2007; Morales-Mulia, 2013), increases in response to acute (Hattori et al, 1994) and chronic treadmill training (Gilliam et al, 1984), and is up-regulated in the striatum of mice selectively bred for high levels of activity-wheel running (Mathes et al, 2010). The motivational drive to run is plausibly mediated by striatal enkephalinergic neurotransmission in the nucleus accumbens septi (NAS) and olfactory tubercle (OT) or through the efferent targets of these neurons in the ventral pallidum (LeMoine et al, 1990; Young et al, 1986).…”