DOPAMINE

a) HOMOVANILLIC ACID

   Homovanillic acid is the main metabolite of dopamine. Increased total homovanillic acid levels are reported in autistic children. (Garreau et al, 1988; Martineau et al, 1987)

   Homovanillic acid levels are regulated by thyroid status. Cardiac muscles of hyperthyroid rats exhibited a 16% decrease in the levels of 1-dopa, 3-methoxytyramine (3-MT) and homovanillic acid (HVA) as compared with those in euthyroid rats (Mano et al, 1998).

b) DOPAMINE-BETA-HYDROXYLASE

   Plasma Dopamine-beta-hydroxylase (DBH) are elevated in autistic children.

   They are also elevated in hypothryoidism (Garnier et al, 1986). Thyroid function controls DBH level in serum  (Stolk et al, 1980).

    T4 treatment decreases dopamine in the CSF. “Results support the notion that there is an interaction between thyroid function and CSF disposition of monoamine compounds” (Sjoberg et al, 1998).

   Neonatal hypothyroidism induces striatal dopaminergic dysfunction (Vaccari et al, 1990)

   The modulatory role of thyroid status in regulating dopamine concentration in the pituitary and hypothalamus and consequently prolactin secretion by the pituitary, has been demonstrated  (Mizukami et al, 1993).

   Dopaminergic and serotoninergic systems are involved in regulation of prolactin (PRL) and TSH secretion. Dopamine itself will decrease plasma levels of TSH and in some instances inhibit TSH secretory response to thyrotropin-releasing hormone (TRH). Conversely blockade of dopamine receptors leads to an elevation of circulating TSH (Krulich, 1982).

D1 receptors are coupled to Gq/11 (Jin et al, 1998).

   It is noteworthy that the D4 dopaminergic receptor gene has been localized to this same region of chromosome 11. (see:Trottier et al, 1999)

Ferrari et al (1989) found that in an autistic group, epinephrine and norepinephrine and dopamine were significantly lower in isolated platelets.

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Ferrari P, Bursztejn C, Dreux C, Braconnier A, Zarifian E, Lancrenon S, Fermanian J - "Disorders of catecholamine metabolism in infantile autism.Comparative study of 22 autistic children" Encephale 15(2):255-62 (1989) http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?uid=2752959&form=6&db=m&Dopt=r

Garnier C, Comoy E, Barthelemy C, Leddet I, Garreau B, Muh JP, Lelord G - "Dopamine-beta-hydroxylase (DBH) and homovanillic acid (HVA) in autistic children" J Autism Dev Disord 16(1):23-9  (1986) http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?uid=3957856&form=6&db=m&Dopt=b

Garreau B, Barthelemy C, Jouve J, Bruneau N, Muh JP, Lelord G - "Urinary homovanillic acid levels of autistic children" Dev Med Child Neurol 30(1):93-8 (1988) http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?uid=3371574&form=6&db=m&Dopt=r

Jin LQ, Cai G, Wang HY, Smith C, Friedman E - "Characterization of the phosphoinositide-linked dopamine receptor in a mouse hippocampal-neuroblastoma hybrid cell line" J Neurochem71(5):1935-43 (1998) http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?uid=9798918&form=6&db=m&Dopt=r

Krulich L - "Neurotransmitter control of thyrotropin secretion" Neuroendocrinology 35(2):139-47  (1982) http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?uid=6127638&form=6&db=m&Dopt=r

Mano T, Sakamoto H, Fujita K, Makino M, Kakizawa H, Nagata M, Kotake M, Hamada M, Uchimura K, Hayakawa N, Hayashi R, Nakai A, Itoh M, Kuzuya H, Nagasaka A - "Effects of thyroid hormone on catecholamine and its metabolite concentrations in rat cardiac muscle and cerebral cortex" Thyroid 8(4):353-8 (1998) http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?uid=9588501&form=6&db=m&Dopt=r

Martineau J, Bruneau N, Garreau B, Barthelemy C, Muh JP, Lelord G - "Significance of clinical and biological markers in autistic syndromes in children" Rev Electroencephalogr Neurophysiol Clin 17(2):159-67 (1987) http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?uid=3321252&form=6&db=m&Dopt=r

Mizukami M, Kishida S, Hirai M, Ooya E, Nakai T, Miyabo S - "The effects of short and long duration of hypothyroidism on prolactin secretion in rats" Nippon Naibunpi Gakkai Zasshi 69(11):1129-38 (1993) http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?uid=8293854&form=6&db=m&Dopt=r

Sjoberg S, Eriksson M, Nordin C - "L-thyroxine treatment and
neurotransmitter levels in the cerebrospinal fluid of hypothyroid patients: a pilot study" Eur J Endocrinol 139(5):493-7(1998) http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?uid=9849813&form=6&db=m&Dopt=r

Stolk JM, Hurst JH, Nisula BC - "The inverse relationship between serum dopamine-beta-hydroxylase activity and thyroid function" J Clin Endocrinol Metab 51(2):259-64 (1980) http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?uid=7400296&form=6&db=m&Dopt=r

Trottier G, Srivastava L Walker CD, - "Etiology of infantile autism: a review of recent advances in genetic and neurobiological research" J Psychiatry Neurosci 24(2):103-115 (1999)] FULL TEXT: http://www.cma.ca/jpn/vol-24/issue-2/0103.htm

Vaccari A, Rossetti ZL, de Montis G, Stefanini E, Martino E, Gessa GL - "Neonatal hypothyroidism induces striatal dopaminergic dysfunction" Neuroscience 35(3):699-706 (1990) http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?uid=2199846&form=6&db=m&Dopt=r