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D H Versteeg

Publications and source records attributed to D H Versteeg.

At least 109 records · Page 6Linked to original sources
PubMed1979

Neurohypophyseal principles and memory.

The neurohypophyseal hormones vasopressin and oxytocin modulate memory processes. Vasopressin facilitates, while oxytocin attenuates memory consolidation and retrieval. These influences are located in different regions of the molecules. Thus, the neurohypophyseal hormones act as precursor molecules for neuropeptides involved in memory processes. The covalent ring structures of both vasopressin and oxytocin mainly affect consolidation; the linear parts, retrieval processes; while nearly the whole oxytocin or vasotocin molecule is needed for attenuation of consolidation and retrieval. Regional studies, utilizing microdissection techniques in combination with a sensitive radioenzymatic catecholamine assay, revealed a distinct pattern of effects on cerebral alpha-methyl-p-tyrosine methylester-induced catecholamine disappearance following intraventricular vasopressin administration in limbic midbrain structures. In situations in which the amount of bioavailable vasopressin in the brain is absent, as is the case in the Brattleboro rat with hereditary diabetes insipidus, or neutralized in normal Wistar rats following the intraventricular administration of antivasopressin serum, regional catecholamine disappearance in most cases is altered in a direction opposite to that observed after intracerebroventricular vasopressin administration. These results indicate that vasopressin modulates memory processes by modulation of neurotransmission in distinct catecholamine systems. Recent experiments suggest that the influence of vasopressin on memory consolidation is mediated by the dorsal noradrenergic bundle via terminal regions of this bundle.

Amnesia↗
PubMed1976

Regional concentrations of noradrenaline and dopamine in rat brain.

The concentrations of noradrenaline and lopamine of 92 brain regions have been measured by a radiometric method which enabled discrimination between noradrenaline and adrenaline. Almost all brain regions investigated contained both noradrenaline and lopamine in measurable amount. However, both catecholamines appeared to be unevenly distributed. Very high dopamine concentrations were measured in the olfactory tubercle, the nucleus accumbens, the caudate nucleus and the rostral part of the medial forebrain bundle; the globus pallidus, the nucleus tractus diagonalis and the nucleus septalis lateralis were also very rich in dopamine. Outside the telencephalon the dopamine concentrations were rather low, except in the median eminence and the area tegmentalis ventralis (Tsai), an area corresponding to the A10 region. High noradrenaline concentrations were measured in most hypothalamic nuclei. Relatively high concentrations of this catecholamine were also measured in several mesencephalic (the ventral part of the central gray, the nucleus raphe dorsalis and the nucleus cuneiformis) and pontine (the locus coeruleus and the nuclei parabrachiales) regions. The highest noradrenaline concentrations in the medulla oblongata were observed in the A2 region and the nucleus commissuralis, which contained at least twice as much noradrenaline as did the more rostral part of the nucleus tractus solitarii.

Animals↗
PubMed1976

Brain-stem structures and catecholamines in the control of arterial blood pressure in the rat.

1. Noradrenaline, adrenaline and alpha-methylnoradrenaline administration into the nucleus tractus solitarii (NTS) of anaesthetized rats decreased blood pressure and heart rate in a dose-dependent fashion. 2. Bilateral injections were effective in lower doses than unilateral administration. alpha-Methylnoradrenaline given bilaterally produced hypotension in a dose of 0-08 nmol whereas after unilateral injection a dose of 0-32 nmol was needed to obtain the same degree of hypotension. 3. Electrical stimulation of the NTS caused hypotension and bradycardia. Conversely, bilateral electrolytic lesions or deafferentation of the NTS led to acute hypertension. Chronically such lesions caused neurogenic hypertension. 4. In spontaneously hypertensive rats increased concentrations of noradrenaline, adrenaline and dopamine were measured in the part of the NTS located just caudal to the obex (A2 region).

Animals↗
PubMed1976

Correlation between hypothalamic catecholamine synthesis and ether stress-induced ACTH secretion.

The rates of synthesis of norepinephrine (NE) and dopamine (DA) in several regions of the hypothalamus have been estimated after exposure of rats to stresses that increase ACTH secretion. The rate of 3H-NE and 3H-DA accumulation from 3H-tyrosine in vitro was used as an index of catecholamine synthesis rates. Exposure to ether vapor, 30 min of cold environment, or laparotomy increased ACTH secretion significantly, as indicated by plasma corticosterone levels. However, only the ether stress affected hypothalamic catecholamines; both NE and DA synthesis rates were increased in the arcuate nucleus are (ANA), but not in the median eminence (ME) or the residual hypothalamus (RH). Dexamethasone treatment blocked the stress-induced ACTH secretion, but had no affect on basal or stress-induced rates of amine synthesis. It is concluded that catecholamines in the ANA participate in mediating ether stress-induced ACTH secretion.

Adrenocorticotropic Hormone↗