Eh. Cook et al., PLATELET SEROTONIN STUDIES IN HYPERSEROTONEMIC RELATIVES OF CHILDREN WITH AUTISTIC DISORDER, Life sciences, 52(25), 1993, pp. 2005-2015
Platelet serotonin (5-HT) studies were conducted with 12 hyperserotone
mic and 12 normoserotonemic age-, sex-, and relationship-matched relat
ives of autistic probands. Each group consisted of 7 mothers, 4 father
s, and 1 sister of autistic children and adolescents. The density (B(m
ax)) of platelet 5-HT2 receptor binding sites, labelled with [H-3]-lys
ergic acid diethylamide (LSD), was significantly lower in 11 hypersero
tonemic subjects compared to 12 normoserotonemic subjects (40.9 +/-13.
5 fmol/mg protein, 59,6 +/- 13.2; p < 0.004). The affinity (K(d)) for
[H-3]-LSD binding did not differ. Although the density (B(max)) of [H-
3]-paroxetine binding did not differ between groups, there was a small
difference in the affinity (K(d)) of [H-3]-paroxetine binding (hypers
erotonemic 47.6 +/- 9.0 pM, normoserotonemic 54.8 +/-12.1; p < 0.05).
There were no significant differences in platelet 5-HT uptake, or in t
hrombin-stimulated 5-HT release. Basal, 5-HT-stimulated, and arginine-
vasopressin (AVP)-stimulated inositol phosphate production, as well as
basal, prostaglandin E1 (PGE1)-, and forskolin-stimulated cAMP produc
tion did not differ. There were signficant correlations between whole
blood 5-HT levels and LSD B(max) (r(S) = -0.63, N=23, p < 0.002) and w
hole blood 5-HT levels and 5-HT uptake V(max) (r(S) = 0.56, N=18, p <
0.02). However, [H-3]-LSD labelled 5-HT2 binding and 5-HT uptake were
not correlated with each other. Hyperserotonemia of autism may be hete
rogeneous with one subgroup of subjects with increased 5-HT uptake and
another subgroup with decreased 5-HT2 binding.