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Biomedical subjects

D de Wied

Publications and source records attributed to D de Wied.

At least 55 records · Page 3Linked to original sources
PubMed1989

Vasopressin maintains long-term potentiation in rat lateral septum slices.

In brain slices of normal Wistar and Long-Evans rats, brief high frequency stimulation of the fimbria fibers induced long-term potentiation (LTP) in excitatory transmission between these fimbria fibers and neurons of the lateral septum (LS). Slices prepared from diabetes insipidus (DI) Brattleboro rats, that contained no vasopressin (VP), consistently failed to maintain LTP in this excitatory transmission. Exogenous VP, administered to slices from DI Brattleboro rats shortly prior to the experiment or released from a subcutaneous depot in DI Brattleboro rats for several days prior to decapitation, corrected this failure. The maintenance of LTP in the LS in slices from Wistar and Long-Evans rats was prevented by D(CH2)5-Tyr(Me)-arginine VP, an antagonist for the V1 type of VP receptors. These results indicate an important role of VP in the maintenance of LTP in excitatory transmission in the LS. It is conjectured that the effects of VP on LS neurons are related to the role of the peptide in the maintenance of LTP and that these processes play a role in memory formation.

Action Potentials↗
PubMed1989

Cardiovascular effects of increasing sodium chloride concentrations microinjected into the nucleus tractus solitarii of the rat.

Unilateral microinjection of increasing sodium chloride concentrations (154.0-256.6 mM) into the nucleus tractus solitarii (NTS) of urethane-anesthetized rats evoked hypotension and bradycardia. The effect was elicited only in a restricted area of the mediocaudal NTS. Microinjection of demineralized water, an isotonic sucrose solution and artificial cerebrospinal fluid were without effect. The possible existence of sodium-sensitive neurons in the NTS is discussed.

Animals↗
PubMed1989

Neuropeptides: animal behaviour and human psychopathology.

Animal studies have demonstrated that neuropeptides modulate nervous system functions. It has been postulated that disturbances in neuropeptide systems may be aetiological factors in psychiatric and neurological disorders. Neuropeptides related to ACTH/MSH, including ORG 2766, increase motivation and attention and facilitate recovery processes after nerve damage. These peptides may be effective during the early stage of dementia. Vasopressin and related peptides improve memory processes in animals and humans. In addition, these peptides influence social behaviour, mood and addictive behaviour. The non-opioid gamma-type endorphins have neuroleptic-like activities in animals and antipsychotic effects in a category of schizophrenic patients. Peptides related to CCK have also been found to be effective in these patients. Some neuropeptides, e.g. TRH and PLG, have been reported to exert antidepressant effects. Further research may eventually produce neuropeptides with therapeutic action in psychiatric and neurological diseases.

Aging↗
PubMed1989

Beta-endorphin and related peptides suppress phorbol myristate acetate-induced respiratory burst in human polymorphonuclear leukocytes.

In the present study, the immunomodulatory effect of beta-endorphin (beta-E) and shorter pro-opiomelanocortin (POMC) fragments was evaluated by assessing their influence on respiratory burst in human polymorphonuclear leukocytes (PMN). The effect of the peptides (10(-17)M - 10(-10)M) on phorbol myristate acetate (PMA)-stimulated production of reactive oxygen metabolites was measured in a lucigenin-enhanced chemiluminescence (CL) assay. Both POMC peptides with opiate-like activity (i.e. alpha-endorphin (alpha-E), beta-E and gamma-endorphin (gamma-E] and their non-opioid derivatives (i.e. des-TYR1-beta-endorphin (dT beta E), des-TYR1-gamma-endorphin (dT gamma E), and des-ENK-gamma-endorphin (dE gamma E] were tested. With the exception of alpha-E, PMA-stimulated respiratory burst was suppressed by all POMC fragments tested. A U-shaped dose-response relation was observed. Doses lower than 10(-17)M and higher than 10(-8)M were without effect. beta-E and dT beta E both suppressed PMA-induced oxidative burst in human PMN at physiological concentrations (10(-16)M - 10(-10)M). gamma-E and dT gamma E proved to be less potent inhibitors, reaching maximal effect at higher concentrations (10(-12)M - 10(-10)M). DE gamma E exerted an even less pronounced but still significant suppressive effect at the concentration of 10(-10)M. None of the endorphins tested was shown to affect resting oxidative metabolism in the PMN. The modulatory effects of the opioid peptides could not be blocked by the opioid antagonist naloxone (10(-8)M). These data show that fragments derived from the POMC-precursor molecule modulate the activation of PMN by suppressing PMA-stimulated oxidative metabolism and that this activity does not involve a classical opiate-like receptor.

Endorphins↗
PubMed1989

Effects of environmental stimuli on immunoreactivity: further studies on passive avoidance behavior.

Rats were immunized against sheep red blood cells (SRBC) immediately after the passive avoidance test; 5 days later the antibody response was measured by determining the number of splenic antibody-secreting B cells. Subjection of rats to habituation trials in the passive avoidance apparatus (apparatus control group) resulted in an enhanced number of antibody secreting cells compared to rats that remained in their home cage. The same phenomenon was observed in rats that were immunized immediately after the learning trial (electric footshock). In animals that showed passive avoidance behavior when tested for retention 24 h after the learning trial, the initially enhanced immune response was down-regulated to the level of rats that remained in their home cage or even lower. The above-mentioned alteration in number of anti-SRBC antibody-secreting cells was only observed in rats that were immunized 15 min after the retention test. In rats that were immunized 1, 4, or 8 h after the retention test no alteration in primary antibody response was observed. In rats of the apparatus control group that were immunized immediately after the retention test an elevated primary antibody response was observed 4, 5, 6, and 7 days after immunization; thus, the changes in immune response were not the consequence of a delayed or accelerated induction of the anti-SRBC response. No change in the absolute number of leukocytes in peripheral blood was observed in the different experimental groups. Moreover, the observed differences in response were not caused by a shift in the percentage of total T, B, Th, or Ts/c cells. The alteration in primary antibody response was only observed in the spleen. The antibody titer in trunk blood did not differ among the different groups and no significant change in number of antibody-secreting cells in the parathymic lymph node was observed. These results show that rats can specifically register different environmental stimuli and as a consequence of that perception there is a change in antibody-secreting cells in the spleen.

Animals↗
PubMed1988

The distribution and plasticity of [3H]vasopressin-labelled specific binding sites in the canary brain.

[3H]Vasopressin was used to detect and to quantitate specific binding sites with in vitro receptor autoradiography in the canary brain. A discrete regional distribution of [3H]vasopressin-labelled binding sites was observed. A high density of specific binding sites was present in the medial posterior hypothalamic nucleus, the superficial layer of the optic tectum, the area ventralis of Tsai (AVT), the nucleus pretectalis, the habenula, the nucleus of Darkschewitch and the nucleus interstitialis. A low density occurred in the nucleus robustus archistriatalis of female birds. However, after testosterone treatment the density of the sites in this area as well as in the AVT increased 2-fold. [3H]Vasopressin binding was displaced to the same extent by excess vasopressin as well as by vasotocin. Moreover, the [3H]vasopressin-labelled brain regions are innervated by immunoreactive vasotocin fibers and terminals. It seems likely therefore that the labelled sites represent putative vasotocin receptors.

Animals↗
PubMed1988

Testosterone-sensitive vasotocin-immunoreactive cells and fibers in the canary brain.

A sexual difference in vasotocin (VT) immunoreactivity was observed in the canary brain. The male canary displays denser VT innervation of the lateral septum and more VT-immunoreactive cells are visible in the dorsal diencephalon than in the female canary. This sex difference is the consequence of gonadal influences. Castration of male canaries resulted in a substantial decrease of VT immunoreactivity in these septal and diencephalic cells and fibers. Testosterone administration to castrated males restored the original intensity of fiber and cell staining. Testosterone treatment of female canaries induced strong VT immunostaining in the above regions similar to that in the male canary.

Animals↗
PubMed1988

Increased concentration of alpha- and gamma-endorphin in post mortem hypothalamic tissue of schizophrenic patients.

The concentrations of alpha-, beta- and gamma-endorphin were determined by radioimmunoassay in HPLC fractionated extracts of post mortem hypothalamic tissue obtained from schizophrenic patients and controls. The hypothalamic concentration of alpha- and gamma-endorphin was significantly higher in patients than in controls (+72.9% and +50.5% respectively). No difference was found in the concentration of beta-endorphin, the putative precursor of alpha- and gamma-endorphins. These results suggest a deviant metabolism of beta-endorphin in the brain of schizophrenic patients. Whether this phenomenon is related to the psychopathology, or is a consequence of ante mortem farmacotherapy, remains to be established.

Adult↗
PubMed1987

Influence of centrally administered alpha- and gamma 2-melanocyte-stimulating hormone on hypothalamic blood flow autoregulation in the rat.

The effect of intracerebroventricularly (i.c.v.) administered alpha-melanocyte-stimulating hormone (MSH) and gamma 2-MSH on hypothalamic blood flow autoregulation was studied in anesthetized rats at different levels of standardized arterial hypotension. Autoregulation was impaired upon i.c.v. administration of 5 micrograms/kg gamma 2-MSH while alpha-MSH caused no changes. Since this effect of gamma 2-MSH was identical to that produced by i.c.v. naloxone in the same model, gamma 2-MSH may be a functional antagonist of central opioid mechanisms participating in the control of cerebral blood flow autoregulation.

Animals↗
PubMed1987

Cardiovascular effects of substance P and capsaicin microinjected into the nucleus tractus solitarii of the rat.

This report deals with the effect of substance P (SP) and capsaicin on blood pressure and heart rate after administration into different sites of the nucleus tractus solitarii (NTS) of urethane-anesthetized rats. Microinjection of SP at 6 different coordinates throughout the NTS showed 3 sites where SP administration evoked changes in blood pressure and heart rate. The most sensitive sites where application of SP into the NTS evoked dose-dependent hypotension and bradycardia were at the level of the posterior tip of the area postrema (zero level) and at the level of the obex. Capsaicin evoked dose-dependent hypotension and bradycardia at the same sites. These results further support the possibility that SP may be a neurotransmitter or neuromodulator of baroreceptor afferents in the NTS.

Animals↗
PubMed1987

Organization of vasotocin-immunoreactive cells and fibers in the canary brain.

The distribution of vasotocin (VT)-immunoreactive neuronal perikarya and fibers in the canary (Serinus canaria) was investigated with immunohistological techniques. The results suggest that most VT-stained cell bodies are located in three diencephalic regions. First, a large number of densely packed neurons are found in the paraventricular nucleus (PVN) and the anterior preoptic nucleus. Neurons here vary widely in size and shape. Small-size rounded neurons and large-size multipolar neurons appear to concentrate in separate subdivisions. Second, a series of loosely organized cell groups of medium- to large-size cells occurs in the lateral parts of the hypothalamus. These aggregates of neurons apparently correspond to subdivisions of the supraoptic nucleus (SON). Third, diffusely distributed, lightly stained cells are found dorsal to the paraventricular nucleus in the dorsal diencephalon. A number of cells of this group seem to be located in the basal septal area and bed nucleus of the stria terminalis. Immunoreactive fibers and varicosities concentrate in brain regions that are associated with neuroendocrine, autonomic, and limbic functions. Axons from the PVN and SON form compact bundles of the hypothalamohypophysial tract in the lateral hypothalamus and then funnel into the internal zone of the medium eminence (ME). Furthermore, a heavy innervation seems to be present in the palisadal, external zone of the ME. A substantial number of fibers appear to leave the PVN toward extrahypothalamic areas. Most extrahypothalamic VT fibers innervate telencephalic and brainstem regions that are thought to be involved in mediation of limbic and autonomic functions. These areas include the lateral and medial septum, the lateral habenula, the substantia grisea centralis, the area ventralis (Tsai), the locus coeruleus, raphe nuclei, the nucleus tractus solitarii, and lateral medulla. In addition, fibers with immunoreactivity for VT innervate structures such as the optic tectum and the nucleus ovoidalis that have been implicated in sensory processing of visual and auditory information. Finally, VT fibers and varicosities occur in centers including the nucleus robustus archistriatalis and nucleus intercollicularis that have been implicated in vocal control.

Animals↗
PubMed1987

Modulation of the immune response by emotional stress.

The influence of mild, emotional stress was investigated for its effect on the immune system by subjecting rats to the one-trial-learning passive avoidance test. The reactivity of the immune system was tested by determining the proliferative response after mitogenic stimulation in vitro as well as the capacity to generate a primary antibody response in vivo after immunization with sheep red blood cells. Our results demonstrate that exposure of rats to a single electric footshock (learning trial) or habituation to the passive avoidance apparatus, induces an increase of the immune response in vitro and in vivo. Thus, emotional stimuli seem to facilitate immunological responsiveness. However, when the animal is confronted with a conflict situation, as tested by the retention of the avoidance response after a single learning trial, the initially enhanced reactivity of the immune system decreases. It is concluded that the immune system is capable of reacting specifically and immediately to distinct psychological stimuli.

Animals↗
PubMed1987

Central opioid mechanisms and cardiovascular control in hemorrhagic hypotension.

Bleeding volume during standardized hemorrhagic hypotension was studied in anesthetized, artificially ventilated rats after specific stimulation or blockade of opiate receptor systems. Hypotension was produced by stepwise bleeding to 80, 60, and 40 mmHg systemic arterial pressure. Subcutaneous administration of morphine 15 min before the bleeding resulted in a decrease, whereas subcutaneous administration of naloxone resulted in a significant increase in the required bleeding volume. Intracerebroventricularly administered met-enkephalin, dynorphin, or specific antisera against these peptides caused no characteristic alterations of the bleeding volume although met-enkephalin and dynorphin caused a significant decrease at the 40 mmHg level. Bleeding volume, however, was markedly reduced when beta-endorphin was intracerebroventricularly administered and significantly elevated by intracerebroventricular administration of a diluted beta-endorphin antiserum. These data suggest that 1) opioid mechanisms are participating in the control of blood pressure and of bleeding volume during blood loss, 2) these control mechanisms might be activated centrally, and 3) beta-endorphin or a closely related peptide plays a major role in these control mechanisms.

Animals↗
PubMed1987

Differential effect of desglycinamide9-(Arg8)-vasopressin on cognitive functions of diabetes insipidus and alcoholic patients.

Intranasal treatment with desglycinamide9-(Arg8)-vasopressin (DGAVP) improved certain aspects of cognitive functions of patients with acquired and congenital diabetes insipidus and of alcoholic patients with mild cognitive impairments. Patients with Korsakoff's syndrome, presenting with severe cognitive impairments, were resistent to DGVP treatment. DGAVP treatment did not affect blood pressure and water metabolism. The action of DGAVP on cognitive functions is probably mediated by centrally located target sites and may be expressed only in patients in whom these target sites are unimpaired.

Administration, Intranasal↗