Summary
A radioenzymatic assay was employed to measure the accumulation of DOPA in a variety of rat brain tissues 30 min after the administration of a decarboxylase inhibitor in order to estimate the activity of dopamine (DA) nerves which terminate in these regions. In the median eminence and posterior pituitary the accumulation of DOPA appears to occur primarily in DA nerves since: (1) the rate of synthesis of norepinephrine (NE), as estimated from theα-methyltyrosine-induced decline of catecholamines, accounts for less than 10% of total catecholamine synthesis in these two brain regions; and (2) the accumulation of DOPA is not significantly altered when the NE concentrations in these regions are reduced to 40–50% of control by prior intraventricular injections of 6-hydroxydopamine. These results suggest that the accumulation of DOPA in the median eminence and the posterior pituitary can be used to estimate the activity of tuberoinfundibular and tuberohypophyseal DA nerves, respectively.
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Alper, R. H., Demarest, K. T., Moore, K. E.: Characteristics of catechol-aminergic nerves in the neurointermediate lobe of the rat pituitary. Soc. Neurosci. Abst.5 (in press, 1979).
Andén, N.-E., Grabowska-Andén, M. Morphine-induced changes in striatal dopamine mechanisms not evoked from the dopamine nerve terminals. J. Pharm. Pharmacol.30, 732–733 (1978).
Brownstein, M., Saavedra, J. M., Palkovits, M. Norepinephrine and dopamine in the limbic system of the rat. Brain Res.79, 431–436 (1974).
Carlsson, A., Lindqvist, M. In vivo measurements of tryptophan and tyrosine hydroxylase activities in mouse brain. J. Neural Transm.34, 79–91 (1973).
Carlsson, A., Kehr, W., Lindqvist, M., Magnusson, T., Atack, C. V. Regulation of monoamine metabolism in the central nervous system. Pharmacol. Rev.24, 371–384 (1972).
Cuello, A. C., Horn, A. S., Mackay, A. V. P., Iversen, L. L. Catecholamines in the median eminence: New evidence for a major noradrenergic input. Nature243, 465–467 (1973).
Demarest, K. T., Moore, K. E.: Accumulation of dihydroxyphenylalanine in the median eminence: An index of tuberoinfundibular dopaminergic nerve activity. Endocrinology (submitted 1979).
Fuxe, T., Hökfelt, T., Nilsson, O. Castration, sex hormones and tuberoinfundibular dopamine neurons. Neuroendocrinology5, 107–120 (1969).
Fuxe, K., Agnati, L., Tsuchiya, L., Hökfelt, T., Johansson, O., Johnsson, G., Lidbrink, P., Löfström, A., Ungerstedt, U. Effect of antipsychotic drugs on central catecholamine neurons of rat brain. In: Antipsychotic Drugs, Pharmacodynamics and Pharmacokinetics (Sedvall, G., ed.), pp. 117 to 132. New York: Pergamon Press. 1975.
Glowinski, J., Iversen, L. L. Regional studies of catecholamines in the rat brain. I. The disposition of3H-norepinephrine,3H-dopamine and3H-DOPA in various regions of the brain. J. Neurochem.13, 655–669 (1966).
Gudelsky, G. A., Annunziatio, L., Moore, K. E. Increase in dopamine content of the rat median eminence after long-term ovariectomy and its reversal by estrogen replacement. Endocrinology101, 1894–1897 (1977).
Hefti, F., Lichtensteiger, W. An enzymatic-isotopic method for DOPA and its use for the measurement of dopamine synthesis in rat substantia nigra. J. Neurochem.27, 647–649 (1976).
Holzbauer, M., Sharman, D. F., Godden, U. Observations on the function of the dopaminergic nerves innervating the pituitary gland. Neuroscience3, 1251–1262 (1978).
Horn, A. S., Cuello, A. C., Miller, R. J. Dopamine in the mesolimbic system of the rat brain: Endogenous levels and the effects of drugs on the uptake mechanism and stimulation of adenylate cyclase activity. J. Neurochem.22, 264–270 (1974).
Kizer, J. S., Palkovits, M., Zivin, J., Brownstein, M. The effect of endocrinological manipulations on tyrosine hydroxylase and dopamine-β-hydroxylase activities in individual hypothalamic nuclei of the adult male rat. Endocrinology95, 799–812 (1974).
Kizer, J. S., Humm, J., Nicholson, G., Greenley, G., Youngblood, W. The effect of castration, thyroidectomy and haloperidol upon the turnover rates of dopamine and norepinephrine and the kinetic properties of tyrosine hydroxylase in discrete hypothalamic nuclei of the male rat. Brain Res.146, 95–108 (1978).
Lindvall, O., Björklund, A. Organization of catecholamine neurons in the rat central nervous system. In: Handbook of Psychopharmacology, Vol. 9 (Iversen, L. L., Iversen, S. D., Snyder, S. H., eds.), pp. 139–231. New York: Plenum Press. 1978.
Lowry, O. H., Rosebrough, N. J., Farr, A. L., Randall, R. J. Protein measurement with Folin phenol reagent. J. Biol. Chem.193, 265–275 (1951).
Moore, K. E., Phillipson, O. T. Effects of dexamethasone on phenylethanol-amine N-methyltransferase and adrenaline in brain and superior cervical ganglia of adult and neonatal rats. J. Neurochem.25, 289–294 (1975).
Moore, K. E., Annunziato, L., Gudelsky, G. A.: Studies on tubero-infundibular dopamine neurons. In: Dopamine, Advances in Biochemical Psychopharmacology (Roberts, P. J., Woodruff, G. N., Iversen, L. L., eds.), pp. 193–204. 1978.
Pellegrino, L. J., Cushman, A. J. A stereotaxic atlas of the rat brain, ed. 2. New York: Appleton-Century-Crofts. 1968.
Roth, R. H., Murrin, L. C., Walters, J. R. Central dopaminergic neurons: Effects of alterations in impulse flow on the accumulation of dihydroxy-phenylacetic acid. Eur. J. Pharmacol.36, 163–172 (1976).
Saavedra, J. M., Palkovitz, M., Kizer, J. S., Brownstein, M., Zivin, J. A. Distribution of biogenic amines and related enzymes in the rat pituitary gland. J. Neurodiem.25, 257–260 (1975).
Selmanoff, M. K., Pramik-Holdaway, M. J., Weiner, R. I. Concentrations of dopamine and norepinephrine in discrete hypothalamic nuclei during the rat estrous cycle. Endocrinology99, 326–329 (1976).
Sokal, R. R., Rohlf, F. J. Biometry, ed. 2. San Francisco: Freeman. 1969.
Umezu, K., Moore, K. E. Effects of drugs on regional brain concentrations of dopamine and dihydroxyphenylacetic acid. J. Pharmacol. Exp. Ther.208, 49–56 (1979).
Walters, J. R., Roth, R. H. Dopaminergic neurons: Drug-induced antagonism of the increase in tyrosine hydroxylase activity produced by cessation of impulse flow. J. Pharmacol. Exp. Ther.191, 82–91 (1974).
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Demarest, K.T., Alper, R.H. & Moore, K.E. Dopa accumulation is a measure of dopamine synthesis in the median eminence and posterior pituitary. J. Neural Transmission 46, 183–193 (1979). https://doi.org/10.1007/BF01250784
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DOI: https://doi.org/10.1007/BF01250784