Vg. Erwin et al., NEUROTENSIN LEVELS AND RECEPTORS IN HAS AND LAS RAT BRAINS - EFFECTS OF ETHANOL, Pharmacology, biochemistry and behavior, 54(2), 1996, pp. 525-532
Previous studies of neurotensin (NT) levels and NT receptor densities
in specific brain regions of mice selectively bred for differences in
sensitivity to ethanol have shown that NTergic processes may mediate s
ome actions of ethanol. In the present study, we have determined the l
evels of NT and NT receptor densities in specific brain regions of HAS
and LAS rats that have been selectively bred for differences in sensi
tivity to ethanol-induced loss of righting response. Regional differen
ces in NT levels were observed in brains from both HAS and LAS rats an
d values in hypothalamus, ventral midbrain, and nucleus accumbens from
female rats were 25 to 75% higher than levels in corresponding region
s from male rats. However, there were no significant line differences
in NT-ir levels in corresponding regions from HAS and LAS animals. Hig
h-affinity binding (NTH B-max values), measured by Scatchard analyses,
were higher in ventral midbrain from HAS males than from LAS males. N
TH receptor densities were higher in HAS males than in HAS females; se
x differences were not observed in the LAS line. There were no signifi
cant line or sex differences between HAS and LAS in low-affinity (NTL)
B-max values in any brain region. In HAS females, subhypnotic doses o
f ethanol produced a decrease in NT levels in nucleus accumbens, where
as, hypnotic doses caused an increase in NT levels. Likewise, hypnotic
doses elicited increases in NT levels in hypothalamus of female HAS a
nd LAS, but not in ventral midbrain or caudate putamen. These results
are consistent with low dose activation of mesolimbic and nigrostriata
l dopaminergic neurons in which NT is colocalized with dopamine and wi
th high dose inhibition of these pathways.