A and B Forms of Monoamine Oxidase Within the Monoaminergic Neurons of the Rat Brain

Abstract

The inhibition of the A and B forms of monoamine oxidase (MAO) inside and outside serotonergic, noradrenergic, and dopaminergic synaptosomes in homogenates of rat hypothalamus or striatum by clorgyline, a selective and irreversible MAO-A inhibitor, and selegiline, a selective and irreversible MAO-B inhibitor, was examined. Intrasynaptosomal deamination at low concentrations of the substrates ['4C]5-hydroxytryptamine ([14Cj5-HT; 0.1 p M ) , [14C]noradrenaline (0.25 p M ) , [14C]3,4-dihydroxyphenylethylarnine ([I4C]dopamine; 0.25 p M ) , and [I4C]tyramine (0.25 p M ) was hindered by selective uptake inhibitors (citalopram, maprotiline, and amfonelic acid) in the incubation media. Thus, the difference between the deamination of I4C-amine in the absence and presence of the appropriate selective uptake inhibitor provided a measure of deamination in the specific aminergic synaptosomes. This was verified by determining the loss of M A 0 activity within noradrenergic and serotonergic systems after degeneration of the nerve terminals by the neurotoxins N-chloroethyl-N-ethy1-2-Address correspondence and reprint requests to Dr. S. B . amine; DOPEG, 3,4-dihydroxyphenylglycol; DSP4, N-chlocepted February 16, 1986. roethyl-N-ethyl-2-bromobenzylamine hydrochloride; 5-HIAA, 5-hydroxyindoleacetic acid; 5-HT or serotonin, 5-hydroxytryp-Ross at Research Laboratories, Astra Lakemedel AB, ,5151 85 t a m i n e ; M A O , m o n o a m i n e o x i d a s e ; 6 -O H D A , 6 -Sodertalje, Sweden. hydroxydopamine hydrochloride; PCA, p-chloroamphetamine Abbreviations used: dopamine, 3,4-dihydroxyphenylethyl-hydrochloride. U S A 79, 6385-6389.

Whole exome sequencing reveals inherited and de novo variants in autism spectrum disorder: a trio study from Saudi families

“…However, the patient (ASD-38) reported here to carry PDK3 splice site variant is not affected with Charcot-Marie-Tooth disease, nor does he suffer from any type of neuropathy. Moreover, of the variants detected on the X-chromosome, four were located in genes involved in brain function/development ( PLP1 76 , MAOB 77 , USP9X 78 , and FLNA 79, 80 ) and two were present in genes regulating splicing and/or transcription ( HTATSF1 81 and GPKOW 82, 83 ). Additional rare variants were identified in genes involved in: (i) the hydrolysis of angiotensin II ( ACE2 ) 84 or sulfate esters ( IDS ) 85 and ( ARSH ) 86 ; (ii) or in the ubiquitination and proteasomal degradation of creatine kinase-B ( ASB - 9 ) 87 .…”

Monoamine oxidase A rather than monoamine oxidase B inhibition increases nicotine reinforcement in rats

“…The drug doses used in our study are consistent with previous investigations on the MAO‐inhibiting effects of these drugs. Indeed, chronic treatment with CLOR (2 mg/kg/day) affords complete inhibition of MAO‐A in rats (MAO‐A, 90%; MAO‐B, 10%) (Fagervall & Ross, 1986; Todd & Baker, 1995) and is sufficient to irreversibly inhibit MAO‐A for more than 24 h (Lamensdorf et al. , 1996).…”

Changes in extracellular 5-HIAA concentrations as measured by in vivo microdialysis technique in relation to changes in 5-HT release

“…The proportion between these two ways under in vivo conditions is not known. However, when brain synaptosomes are incubated with low nmol concentrations of radioactive 5-HT rapid formation of 5-HIAA occurs inside the 5-HT synaptosomes (Ross and Ask 1980;Fagervall and Ross 1986). It is therefore likely that a considerable part of the 5-HT taken up is deaminated to 5-HIAA under in vivo conditions.…”