Increased serum levels of glutamate in adult patients with autism

Chukyo University, Koromo, Aichi, Japan
Progress in Neuro-Psychopharmacology and Biological Psychiatry (Impact Factor: 3.69). 03/2007; 30(8):1472-7. DOI: 10.1016/j.pnpbp.2006.06.013
Source: PubMed


Precise mechanisms underlying the pathophysiology of autism are currently unknown. Given the major role of glutamate in brain development, we have hypothesized that glutamatergic neurotransmission plays a role in the pathophysiology of autism. In this study, we studied whether amino acids (glutamate, glutamine, glycine, D-serine, and L-serine) related to glutamatergic neurotransmission are altered in serum of adult patients with autism.
We measured serum levels of amino acids in 18 male adult patients with autism and age-matched 19 male healthy subjects using high-performance liquid chromatography.
Serum levels (mean = 89.2 microM, S.D. = 21.5) of glutamate in the patients with autism were significantly (t = -4.48, df = 35, p < 0.001) higher than those (mean = 61.1 microM, S.D. = 16.5) of normal controls. In contrast, serum levels of other amino acids (glutamine, glycine, d-serine, l-serine) in the patients with autism did not differ from those of normal controls. There was a positive correlation (r = 0.523, p = 0.026) between serum glutamate levels and Autism Diagnostic Interview-Revised (ADI-R) social scores in patients.
The present study suggests that an abnormality in glutamatergic neurotransmission may play a role in the pathophysiology of autism.

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    • ", 1 , 8 ↔ Serum, plasma 7 (9 studies) (D'Eufemia et al., 1995; Aldred et al., 2003; Shinohe et al., 2006; Paşca, 2009; Adams et al., 2011; Shimmura et al., 2011; Tirouvanziam et al., 2012) "
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    • "Decreased in plasma [8, 16, 17, 21] Lysine Increased in plasma [8, 10, 16] No difference in plasma [17] Tryptophan Decreased in plasma [16, 17] Taurine Decreased in plasma [16] Increased in plasma [15, 22] Homocysteine Increased in serum [16, 23] Increased total homocysteine (tHcy) in serum [24] Decreased plasma levels of homocysteine [25] Increased level in urine [26] Citrulline Decreased in plasma [17] Alanine No difference in plasma [17] Increased in plasma [10] Glycine No difference in plasma [17] Valine Decreased in plasma [8, 16] No difference in plasma [17] Aspartic acid Decreased platelet levels [27] GABA Decreased platelet levels [27] Arginine No difference in plasma [17] Isoleucine Decreased [21] Threonine Decreased in plasma [17] Serine Decreased in plasma [17] Proline No difference in plasma [17] Asparagine Decreased in plasma [15, 17] Increased in plasma [10] Aspartic acid No difference in plasma [17] Methionine Increased in plasma [8] Decreased [21] Glycine No difference in serum level [19] D-serine No difference in serum level [19] L-serine No difference in serum level [19] Glutamic acid Increased in plasma [10, 16, 17] Decreased platelet levels [27] Glutamate Increased level in plasma [9, 10, 15, 19, 28] Increased in some regions of brain [20] Aspartate Increased in plasma [22] Phenylalanine Decreased in plasma [8] [17] Increased in plasma [10] Glutamine Decreased in plasma [9, 10, 15–17] No difference in serum level [19] Decreased platelet levels [27] Lysine Increased in plasma [10] Tyrosine Decreased in plasma [16] [17] Increased in plasma [10] its higher level is a compensatory phenomenon for the increased glutamate level [15]. Nevertheless, others reported that the mean level of taurine is decreased in autism [16] "
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