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To determine whether prolonged supersensitization of dopamine D-1 receptors could be produced during ontogeny, rats were treated daily, from birth, for 33 consecutive days with the D-1 receptor agonist, SKF 38393 HCl (3.0 mg/kg per day i.p.). These rats were additionally treated at 3 days after birth with the neurotoxin, 6-hydroxydopamine HBr (6-OHDA; 200(More)
The specific binding of [3H]YM-09151-2 was used to investigate the possible differences in age-associated changes in striatal D2 dopamine (DA) receptor properties in genetically obese (fa/fa) Zucker rats and their lean (Fa/?) littermates. The maximal binding sites (Bmax) of D2 DA receptors was found to decline with age in both obese and lean rats; the rate(More)
Rats receive melatonin (MEL) (476 +/- 6.5 microg/kg/day) via their drinking water for 2 weeks. At the end of this period, the density of D2 dopamine (DA) receptors and their affinity for [3H]-YM-09151-2 are measured in the striatum. MEL treatment increases the apparent affinity (decreases the Kd) of D2 DA receptors for [3H]YM-09151-2 by 48%, while it does(More)
The chronic consumption of low doses of nicotine in drinking water for two years consistently increased the sensitivity of rats to a nociceptive thermal stimulus (tail-flick test), but reduced aversiveness in the elevated plus-maze test, relative to the responses of age-matched controls in these tests. The responses of aged nicotine-consuming rats were(More)
Two peptides corresponding to amino acid sequences predicted from the nucleotide sequence of the dopamine D2 receptor were synthesized. Peptide I (CGSEG-KADRPHYC) and peptide II (NNTDQNECIIY), corresponding to 24-34 and 176-185 from the NH2 terminus, respectively, were conjugated to keyhold limpet hemocyanin and injected into rabbits. Peptide I showed a(More)
Using the water tank procedure, we have examined the effects of rapid eye movement (REM) sleep deprivation and associated stress on the properties of striatal dopaminergic system. While stress decreased the number of D1 and D2 dopamine receptors, a combination of REM sleep deprivation attenuated the decrease. The ratio of D1 to D2 densities, however,(More)
The property of D2 dopamine receptors in the rat brain was evaluated after long-term dietary manipulation. Groups of rats were pair-fed with equicaloric diet containing low protein (8%)-high carbohydrate, high protein (52%)-low carbohydrate and normal protein (20%) for 36 weeks. The low protein-high carbohydrate fed rats exhibited a significant decrease in(More)
In the present ultrastructural study in the ventrocaudal periaqueductal gray (PAG) of the rat, the relationship and the association between GABAergic and enkephalinergic neuronal elements were investigated using postembedding colocalization immunogold electron microscopic technique in order to establish the precise relationship between these two important(More)
The influence of central dopaminergic fibers on drug-induced oral activity in rats has not been well studied. Rats were treated 3 days after birth with bilateral intracerebroventricular 6-hydroxydopamine (6-OHDA; 134 micrograms total, base form) to destroy dopaminergic fibers in the brain. Control rats received vehicle by the same route. At about 10 weeks(More)
Rats that consume a diet 50% rich in protein exhibit hyperactivity and hyperresponsiveness to nociceptive stimuli, in which facilitation of dopaminergic activity has been implicated. We studied the regional changes in the concentrations of dopamine (DA) and its metabolites, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the brains of rats(More)