Cf. Phelix et Pa. Broderick, LIGHT-MICROSCOPIC IMMUNOCYTOCHEMICAL EVIDENCE OF CONVERGING SEROTONINAND DOPAMINE TERMINALS IN VENTROLATERAL NUCLEUS-ACCUMBENS, Brain research bulletin, 37(1), 1995, pp. 37-40
The mesencephalic tegmentum contains monoaminergic neurons that projec
t to the nucleus accumbens (NAcc), These monoaminergic neurons consist
of the serotonergic (5-HT) neurons of the dorsal and median raphe and
the dopaminergic (DA) neurons of the ventral tegmental area (VTA). Re
cent neurochemical reports describe cocaine-induced alterations in dop
amine and serotonin release in NAcc that has coincidental occurrence b
oth spatially and temporally, as shown by in vivo voltammetry, There i
s a functional role for 5-HT-DA interactions within the NAcc in the un
derlying mechanism of action of cocaine as well as for 5-HT in A10 DA
neurons in the basal or endogenous state whether or not cocaine-releva
nt reward circuits are involved. Our objective was to study the neuroa
natomic localization of tyrosine hydroxylase-containing (TH) and 5-HT-
containing axons in the ventrolateral region of the rat NAcc, where co
detection of monoamines had been assessed. The significance of this vl
NAcc is its reciprocal connectivity with VTA, which contains the somat
odendritic portions of the mesoaccumbens DA neurons. The results showe
d that, in the vlNAcc, the core contained a dense terminal field of TH
axons that had an extensive overlap with 5-HT axons in the periphery
within the core, Because the in vivo electrochemical codetection of DA
and 5-HT assessed in the ventral-most aspect of this overlap zone can
be correlated with terminal release, a functional interaction of 5-HT
and DA at postsynaptic sites in vlNAcc is possible.