Effect of psychotropic drugs on 3,4-dihydroxyphenylacetic acid (DOPAC) content in the medial basal hypothalamus

Argiolas, Antonio; Paglietti, E.; Fadda, F; Quarantotti, B. Pellegrini; Gl, Gessa

doi:10.1016/0024-3205(78)90425-3

Cited by 16 publications

(7 citation statements)

References 14 publications

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“…Similar DA/DOPAC ratios were reported in other dopaminergically innervated areas e.g. 3.44 for the medial basal hypo thalamus [3] and 5.12 for the caudate nucleus [11].…”

Section: Kinetics O F 3 H-da Uptake In the Nilsupporting

confidence: 67%

Characteristics of Dopamine Uptake and 3,4-Dihydroxyphenylacetic Acid (DOPAC) Formation in the Dopaminergic Terminals of the Neurointermediate Lobe of the Pituitary Gland

Annunziato¹,

Weiner²

1980

Neuroendocrinology

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The kinetics of dopamine (DA) uptake were studied in synaptosomal preparations of the neurointermediate lobe (NIL) of the pituitary gland, a region containing the terminals of the tuberoinfundibular dopaminergic neurons. Lineweaver-Burk plots of the initial velocity of DA uptake versus the concentration of DA yielded a single straight line in the NIL. The K_m values in the NIL of the rat and the steer were 2.2 ± 0.5 × 10^–6M and 2.0 ± 0.1 × 10^–6M, respectively. The uptake was predominantly into dopaminergic terminals since preincubation with desipramine did not affect the V_max or K_m of DA uptake. Oberved uptake was predominantly due to transport across the neuronal membrane and not into storage granules, since reserpine caused only a small decrease in uptake. The concentration of the DA metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) in the NIL was 3.6 ng/mg protein. The ratio of DA to DOPAC in the NIL (3.73) was similar to that obtained in the medial basal hypothalamus, another region innervated by the tuberoinfundibular dopaminergic neurons. The kinetics of DA uptake in the nerve terminals of the NIL are similar to those observed in the DA terminals in the median eminence. The affinity of uptake in the terminal fields of the tuberoinfundibular system is considerably lower than in terminals of the mesolimbic and nigrostriatal dopaminergic terminals.

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“…Similar DA/DOPAC ratios were reported in other dopaminergically innervated areas e.g. 3.44 for the medial basal hypo thalamus [3] and 5.12 for the caudate nucleus [11].…”

Section: Kinetics O F 3 H-da Uptake In the Nilsupporting

confidence: 67%

Characteristics of Dopamine Uptake and 3,4-Dihydroxyphenylacetic Acid (DOPAC) Formation in the Dopaminergic Terminals of the Neurointermediate Lobe of the Pituitary Gland

Annunziato¹,

Weiner²

1980

Neuroendocrinology

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“…Recently it has been found by two groups of investiga tors [1,24] that in the median eminence, unlike the striatum, the levels of 3,4-dihydroxyphenylacetic acid (DOPAC), a DA metabolite, are not a good index of DA turnover. It has been demonstrated that increases in DOPAC levels are de pendent on DA reuptake [27], Since the affinity of the reup take is very low in the terminals of tuberoinfundibular neur ons, the DA metabolite cannot be adequately formed.…”

Section: Discussionmentioning

confidence: 99%

“…Experiments characterizing the reuptake system have been performed in tissue slices or in synaptosomes [5,12]. On the other hand, the tuberoinfundibular dopaminergic system, another central DA pathway, has anatomical and neuropharmacological properties which are qualitatively 1 Supported by N1H Grant Number HD 08924 and a Rockefeller Foundation Center Grant. 2 Preliminary reports of this work were presented at the 63rd Fed eration of American Societies for Experimental Biology Meeting, March 1979.…”

mentioning

confidence: 99%

Differences in the Kinetics of Dopamine Uptake in Synaptosome Preparations of the Median Eminence Relative to Other Dopaminergically Inervated Brain Regions

et al. 1980

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A comparison of the kinetics of dopamine uptake was made in synaptosomal preparations of the median eminence, striatum and olfactory tubercle. Double reciprocal Lineweaver-Burk plots of the initial velocity versus the concentration of dopamine yielded a single straight line in all three areas. The Michaelis constant (K_m) in the median eminence (1.8 ± 0.9 × 10^–6M) was significantly higher (p<0.05) than in the striatum (4.2 ± 0.8 × 10^–8M) or olfactory tubercle (6.3 ± 1.9 × 10^–8M). Uptake in the median eminence appeared to be predominantly into dopaminergic terminals since preincubation with desipramine did not affect the maximum velocity (V_max) of dopamine uptake. Observed uptake was predominantly due to transport across the neuronal membrane and not into storage granules, since reserpine only caused a small decrease in uptake. The low affinity of dopamine uptake in median eminence synaptosomes is consistent with the neurose-cretory nature of these terminals, whereas, in the striatum and olfactory tubercle, high affinity reuptake is consistent with the role of dopamine as a neurotransmitter.

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“…DA neurons in the mediobasal hypothala mus are especially sensitive to reserpine treatment [3,17,43]. Previous studies have shown that DA levels in the median emi nence are significantly depleted by low doses of resperpine as early as one hour after ad ministration [3,17], Reserpine was employed in this study to examine whether or not the DA neurons remaining in the hypothalami of MSG-treated mice would be sensitive to the effects of RES.…”

Section: Discussionmentioning

confidence: 99%

“…Previous studies have shown that DA levels in the median emi nence are significantly depleted by low doses of resperpine as early as one hour after ad ministration [3,17], Reserpine was employed in this study to examine whether or not the DA neurons remaining in the hypothalami of MSG-treated mice would be sensitive to the effects of RES. Our findings indicate that the surviving DA neurons in MSG-treated mice do not exhibit the RES sensitivity character istic of tuberoinfundibular DA neurons since they were resistant to RES-induced DA de pletion.…”

Section: Discussionmentioning

confidence: 99%

Hypothalamic Monoamine Metabolism in Mice: Evaluation of Drug Challenges and Neurotoxic Insult

Dawson¹,

Callahan

Annau

1986

Pharmacology

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Hypothalamic monoamine metabolism was evaluated in male and female mice that were administered monosodium glutamate (MSG, 4 mg/g) on postnatal day 4. Hypothalamic dopamine (DA) content was reduced approximately by 22% across all experiments and pituitary DA content was also significantly decreased. Despite reductions in hypothalamic DA levels, MSG-treated mice did not exhibit significant reductions in the levels of the DA metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA). Hypothalamic monoamine and metabolite profiles in MSG-treated and control mice were examined after the administration of pargyline (PAR), α-methyl-p-tyrosine (MPT) or reserpine (RES). DA turnover as indexed by PAR and MPT techniques were not as conclusive as the metabolite measures in suggesting an accelerated DA utilization. MSG-treated mice were more resistant to the DA-depleting actions of reserpine than were the controls. No alterations were found in hypothalamic norepinephrine metabolism in MSG-treated mice, however, after drug challenges, alterations were found in serotonin metabolism. These results indicate the extent and nature of the changes that occur in hypothalamic monoamine metabolism after neonatal MSG treatment. The DA neurons that survive MSG treatment appear to exhibit neurochemical characteristics dissimilar to those of tuberoinfun-dibular DA neurons. Additionally, the neuropharmacological actions of MPT, PAR and RES are discussed as they relate to hypothalamine monoamine metabolism in the mouse.

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Effect of psychotropic drugs on 3,4-dihydroxyphenylacetic acid (DOPAC) content in the medial basal hypothalamus

Cited by 16 publications

References 14 publications

Characteristics of Dopamine Uptake and 3,4-Dihydroxyphenylacetic Acid (DOPAC) Formation in the Dopaminergic Terminals of the Neurointermediate Lobe of the Pituitary Gland

Characteristics of Dopamine Uptake and 3,4-Dihydroxyphenylacetic Acid (DOPAC) Formation in the Dopaminergic Terminals of the Neurointermediate Lobe of the Pituitary Gland

Differences in the Kinetics of Dopamine Uptake in Synaptosome Preparations of the Median Eminence Relative to Other Dopaminergically Inervated Brain Regions

Hypothalamic Monoamine Metabolism in Mice: Evaluation of Drug Challenges and Neurotoxic Insult

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