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  • Rat  (6)
  • 5-hydroxytryptamine  (3)
  • Hypothalamus  (2)
  • 1
    ISSN: 1432-1912
    Keywords: Dopamine ; Noradrenaline ; Hypothalamus ; Forebrain ; Nicotine ; Pentobarbitone ; Adenohypophyseal hormones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of single intraperitoneal injections of nicotine (1 mg/kg) and the sedative-hypnotic drug pentobarbitone (30 mg/kg) alone or in combination have been studied on catecholamine (CA) nerve terminal system of the hypothalamus and the forebrain and on the adenohypophyseal hormone secretion of the normal male rat. Nicotine produced discrete reductions of dopamine (DA) levels and increases of DA turnover in striatal and limbic areas of the forebrain and increases of amine turnover in different hypothalamic noradrenaline (NA) nerve terminal systems. These effects were all antagonized by simultaneous treatment with pentobarbitone. Pentobarbitone alone, however, did not modulate CA levels or turnover in the various parts of the hypothalamus and forebrain analyzed. On the other hand, pentobarbitone increased GH and prolactin secretion and in association with tyrosine hydroxylase inhibition markedly reduced corticosterone secretion. These effects were partly counteracted by nicotine in the case of GH and prolactin secretion. Furthermore, a positive interaction appears to exist between nicotine and pentobarbitone in their actions on LH secretion. The results suggest that pentobarbitone can antagonize the actions of nicotine on CA levels and turnover in various CA nerve terminal systems of the brain leading to possible reductions in nicotine induced arousal and positive reinforcement. The neuroendocrine actions of pentobarbitone do not seem to be greatly modulated through nicotinic cholinergic receptors.
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  • 2
    ISSN: 1432-1912
    Keywords: Nicotine ; Cigarettes ; Catecholamine ; Hypothalamus ; Anterior pituitary hormones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of acute continuous exposure to the smoke from 1–4 cigarettes have been studied in the male rat in terms of hypothalamic catecholamine levels and utilization as well as the secretion of anterior pituitary hormones. Catecholamine levels in discrete hypothalamic catecholamine nerve terminal systems were studied by quantitative histofluorimetry. Catecholamine utilization was studied by means of the tyrosine hydroxylase inhibition method using α-methyl-(±)-p-tyrosine methyl ester. The serum hormone levels of adenohypophyseal hormones and of corticosterone were measured by the use of radioimmunoassay procedures. The results show that acute continuous exposure to unfiltered but not to filtered (Cambridge glass fibre filters) cigarette smoke leads to small but dose-dependent reductions of amine levels in most of the hypothalamic noradrenaline and dopamine nerve terminal system. These effects were associated with an enhancement of regional hypothalamic noradrenaline utilization but not of dopamine utilization in the median eminence. Furthermore, a reduction of TSH and prolactin serum levels was noted as well as increases in ACTH secretion. These results are partly different from those previously obtained with rats acutely exposed to intermittent unfiltered cigarrete smoke. This difference is suggested to be due to a temporary blockade of catecholamine release following acute continuous exposure to cigarette smoke.
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  • 3
    ISSN: 1432-1106
    Keywords: Steroid receptor ; CRF ; Neurotensin ; Enkephalin ; CCK ; PHI ; VIP ; Somatostatin ; TRH ; Dopamine ; Immunohistochemistry ; Arcuate nucleus ; Hormones ; Neurosecretion ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The paraventricular nucleus (PVN) of male albino rats was analyzed for the presence of glucocorticoid receptor-like immunoreactivity (GR-LI) in neuropeptide containing neurons. Using immunohistochemistry, coronal sections trough the entire PVN were double-stained with a mouse monoclonal antibody against GR and one of the following antisera: rabbit antiserum to corticotropin releasing factor (CRF), neurotensin (NT), enkephalin (ENK), cholecystokinin (CCK), thyrotropin releasing hormone (TRH), galanin (GAL), peptide histidine isoleucine (PHI), vasoactive intestinal polypeptide (VIP), somatostatin (SOM) or tyrosine hydroxylase (TH). For comparison the occurrence of GR-LI in NT-, SOM-, NPY- or TH-positive neurons of the arcuate nucleus was also studied. Our results indicate that GR-LI is present in the parvocellular part of the PVN but not in its magnocellular portion. Virtually every parvocellular neuron in the PVN containing one of the above mentioned peptides was also positive for GR, with the exception of SOM neurons, of which only about two thirds showed detectable levels of GR-LI. All TH-positive, presumably dopamine neurons in the PVN were GR-positive. In the arcuate nucleus all TH- and NPY-positive neurons as well as a large proportion of the SOM- and NT-immunoreactive neurons contained GR-LI. The results indicate that in the PVN, in addition to the CRF neurons, certain peptidergic neurons in the parvocellular part of the PVN, without any established role in the control of ACTH synthesis and release, may also be under glucocorticoid control. This seems to be the case also for most arcuate neurons.
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  • 4
    ISSN: 1432-1106
    Keywords: Endothelin ; Ischemia ; Striatum ; Microdialysis ; Cerebral blood flow ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present study examines the possibility that lesions induced by intrastriatal injections of endothelin-1 (ET-1, 0.43 nmol/0.5 µl) are ischemic in nature due to a vasoconstriction of the cerebral microvessels. In time course and dose-response experiments with ET-1 and in comparisons with ET-3, the volume of the lesions has been determined based mainly on the disappearance of striatal nerve cells, using a computer assisted morphometrical analysis. The blood flow in the neostriatum close to the site of injection of ET-1 was determined acutely by Laser-Doppler flowmetry. The acute metabolic effects of ET-1 were also studied on striatal superfusate levels of lactate, pyruvate, dopamine and its metabolites DOPAC (3,4-dihydroxyphenylacetic acid) and homovanilic acid (HVA) using an instrastriatal microdialysis probe. Dose related striatal lesions were observed with ET-1 (0.043–0.43 nmol) with a peak lesion volume after 24–48 h and the possible existence of a penumbra area. ET-3 showed a reduced potency to produce striatal lesions compared to ET-1. The lesions induced by ET-1 were prevented by coinjection with dihydralazine, a vasodilator drug. Acutely ET-1 (0.43 nmol/0.5 µl) produced a prolonged reduction of the cerebral blood flow down to 40% of control values and temporary increases of striatal lactate and DA efflux, the latter change being very marked. Also a significant reduction of DOPAC and HVA was observed. These neurochemical changes were all prevented by treatment with dihydralazine. These results indicate that ET-1 injected in the neostriatum may produce lesions by causing local ischemia, related to its vasoconstrictor activity and possibly also to an activation of ET-1 receptors in the astroglial-endothelial complex. Based on the present results it seems possible that ET-1 may participate in the multifactorial pathogenesis of cerebral ischemia.
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  • 5
    ISSN: 1432-1106
    Keywords: Endothelin-1 ; Striatum ; Ischemia ; Microdialysis ; Cerebral blood flow ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have studied the ability of the vigilance-promoting drug modafinil to counteract the ischemic lesion produced by a unilateral microinjection of endothelin-1 (ET-1) in the neostriatum of the rat using a combined morphometrical, biochemical, cardiovascular and behavioral analysis. ET-1 was injected unilaterally into the neostriatum. The ET-1-induced lesion volume, which was determined by a computer-assisted morphometrical analysis, was reduced by the 7-day modafinil treatment (10, 30, and 100 mg/kg i.p.) in a dose-related way. Modafinil also produced a dose-related counteraction of the ET-1-induced increase of perfusate lactate levels, as determined by intrastriatal microdialysis without affec ting the ET-1 induced reduction of striatal blood flow, as determined by laser-Doppler flowmetry. The ipsilateral rotational behavior induced by apomorphine in the ET-1-lesioned rats was reduced dose-dependently by modafinil treatment. Thus, morphological, neurochemical, and behavioral evidence that the putative ischemic striatal injury induced by microinjection of ET-1 in the rat neostriatum is counteracted in a dose-dependent way by modafinil treatment has been obtained. The mechanism does not appear to involve an increase in striatal blood flow. It is instead speculated that its powerful preventive action in striatal ischemic injury may be related to a reduced anaerobic metabolism.
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  • 6
    ISSN: 1432-1106
    Keywords: Dopamine ; Substantia nigra ; Striatum ; Hemitransection ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We studied the ability of the vigilance-promoting drug modafinil to modulate the anterograde and retrograde changes in tyrosine hydroxylase (TH) immunoreactivity and in dopamine (DA) stores in the nigro-neostriatal DA neurons, following a partial hemitransection of this ascending DA system, using a combined morphometrical, biochemical and behavioural analysis. Modafinil was given daily i.p. in doses of 10–100 mg/kg, starting 15 min after the lesion, and the partially hemitransected rats were killed 2 weeks later. Changes in TH-immunoreactive nerve cell bodies and nerve terminals induced by the partial hemitransection were studied in the substantia nigra and neostriatum in combination with image analysis. The substantia nigra and neostriatum were also subjected to biochemical analysis of DA, 3,4-dihydroxyphenylacetic acid and homovanillic acid levels. Modafinil treatment dose-dependently (10–100 mg/kg) counteracted the hemitransection-induced disappearance of nigral TH-immunoreactive nerve cell body profiles and neostriatal TH-immunoreactive nerve terminal profiles. A 2-week treatment with 100 mg/kg of modafinil also counteracted the hemitransection-induced depletion of DA stores in the neostriatum and the ventral midbrain. Moreover, the repeated daily treatment with modafinil (100 mg/kg) protected against the hemitransection-induced disappearance of striatal 5-hydroxytryptamine, 5-hydroxyindoleacetic acid and noradrenaline levels. Striatal DA function was analysed by studying apomorphine-induced (1 mg/kg, s.c.) ipsilateral rotational behaviour 4 and 11 days after the operation. A marked dose-dependent reduction of ipsilateral rotational behaviour was demonstrated after the daily modafinil treatment in the partially hemitransected rats. In another model involving unilateral nigral microinjections of 6-hydroxydopamine, acute (one single dose) modafinil (100 mg/kg) did not affect the contralateral rotational behaviour induced by apomorphine (0.05 mg/kg s.c.), when given 30 min before the apomorphine. Taken together, morphological, neurochemical and behavioural evidence has been obtained that anterograde and retrograde changes induced in the DA stores and TH immunoreactivity of the nigro-neostriatal DA neurons by a partial hemitransection are counteracted by modafinil in a dose dependent way with 100 mg/kg producing a significant protective action against impairment of DA transmission. The results of this study open up the possibility that modafinil may protect against the anterograde and retrograde degeneration of nigrostriatal DA neurons seen after mechanically induced injury.
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  • 7
    ISSN: 1432-1106
    Keywords: Peptides ; Glial fibrillary acidic protein ; 4 vessel occlusion model of ischemia ; Immunocytochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of transient (30') forebrain ischemia (4 vessel occlusion model) on peptidergic neurons and astroglial cells in various diencephalic and telencephalic areas have been analyzed. The study was performed at various time intervals of reperfusion, i.e. 4 h, 1, 7 and 40 days. Neuropeptide Y (NPY), somatostatin (SRIF), cholecystokinin (CCK), vasoactive intestinal polypeptide (VIP) and arginin-vasopressin (AVP) immunoreactive (IR) neuronal systems and glial fibrillary acidic protein (GFAP)-IR glial cells have been visualized by means of the indirect immunoperoxidase procedure using the avidin-biotin technique. The analysis was performed by means of computer assisted microdensitometry and manual cell counting. At the hippocampal level a huge reduction of neuropeptide (CCK, SRIF, VIP) IR cell bodies was observed, still present 40 days after reperfusion. On the contrary, in the frontoparietal cortex the number of the neuropeptide (CCK, SRIF, VIP, NPY) IR neurons showed a decrease at 4 h, 1 and 7 days after reperfusion followed by a complete recovery at 40 days. A rapid reduction followed by an almost complete recovery (7 days after reperfusion) was also observed at striatal level where SRIF- and NPY-IR neurons were detected. A marked decrease of NPY-IR terminals was observed in the paraventricular and periventricular hypothalamic nuclei and in the paraventricular thalamic nucleus. AVP-IR was markedly reduced in the magnocellular part of the paraventricular nucleus throughout the analyzed period (7 days after reperfusion). GFAP-IR was increased in the hippocampal formation and neostriatum while a not consistent increase was observed at neocortical level. These data point to a differential recovery of peptide-IR and to a different astroglial response in the various brain areas after transient forebrain ischemia. Region-specific factors rather than factors related to neuronal chemical coding seems to play a major role in determining the vulnerability of neuronal populations to transient ischemia.
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  • 8
    ISSN: 1432-1106
    Keywords: Dopamine ; Dopamine and cAMP regulated phosphoprotein ; DARPP-32 ; Ischemia ; Striatum ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To evaluate the development of striatal ischemic cell damage in relation to alterations in dopamine (DA) transmission, one year old male Wistar rats underwent a 15 min incomplete cerebral ischemia (ICI) induced by occlusion of the common carotid arteries and by hypovolemic hypotension. The animals were divided into the following experimental groups: sham operated rats, rats with ICI without reperfusion, and rats with ICI followed by 60 min, 24 h, 72 h and 144 h of recirculation. The ischemia induced striatal lesions were investigated in serial coronal brain sections, stained with cresylviolet or immunostained for dopamine and cAMP regulated phosphoprotein (DARPP-32), for tyrosine hydroxylase (TH) and for glial fibrillary acidic protein (GFAP) immunoreactivities (IR). Measurements of striatal dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) levels were made on analogous experimental groups using HPLC methods. Signs of degeneration in small to medium sized neurons were already seen after 60 min of postischemic reperfusion together with slight decreases of DARPP-32 IR and increases of GFAP IR. The damage continued to increase up to 144 h, and after 24 h of recirculation there were clearly defined areas of reduced DARPP-32 IR, overlapping with increased TH IR and increased GFAP IR. The levels of DA, DOPAC and HVA increased sharply after 60 min (151%, 462% and 201%, respectively) remained high after 24 h and normalized after 72 h of recirculation. The DA metabolism was high after 60 min and had already normalized after 24 h of recirculation. The increased DA metabolism in striatal nerve terminals in response to ischemic injury may reflect an early degenerative change in the DA terminals. The long-lasting increase in TH IR may to some extent represent an adaptive change in response to the disappearance of DA receptor-containing nerve cells. Based on the present findings it is possible that an increased D1 transmission in neostriatum immediately following the ischemic injury may contribute to striatal nerve cell degeneration in which an enhancement of NMDA receptor transduction may be implicated.
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  • 9
    ISSN: 1435-1463
    Keywords: Glucocorticoid receptor ; image analysis ; rat brain ; imipramine ; noradrenaline ; 5-hydroxytryptamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Glucocorticoid receptor (GR) immunoreactivity (IR) was analyzed semi-automatically in the forebrain and in the lower brain stem of male rats treated for two weeks with imipramine (10 μmol/kg). Serum corticosterone and aldosterone levels were determined by means of radioimmunoassay procedures. The microdensitometric analysis demonstrated a selective increase in the GR IR in the nerve cell nuclei of the locus coeruleus (A6), of the ventral part of the reticular gigantocellular nucleus (B3L) and of the nucleus raphae magnus (B3M), whereas a small reduction of GR IR was found in the nucleus raphe obscurus (B2). In the morphometric analysis significant increases in the mean profile area of nuclear GR IR, which may be secondary to the increase in GR IR, were observed in the B3M. The serum corticosterone and aldosterone levels were not found to be significantly altered. The selective changes of GR IR may reflect the presence of an altered number of GR in these nerve cell groups and/ or an altered translocation of GR to the nuclei. It is of substantial interest that these changes were observed in the presence of unchanged serum levels of corticosterone and aldosterone. It seems possible that adaptive changes in monoamine synapses induced by the chronic imipramine treatment may be responsible for the changes in GR IR found in the noradrenaline (NA) and 5-hydroxytryptamine (5-HT) cell bodies, respectively. The present results open up the possibility that chronic imipramine treatment may help to maintain the glucocorticoid receptor function in the locus coeruleus and in the 5-HT cell groups of the rostral ventromedial medulla of depressed patients.
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  • 10
    ISSN: 1435-1463
    Keywords: 5-hydroxytryptamine ; 5-hydroxyindolacetic acid ; substance P ; thyrotropin releasing hormone ; imipramine ; rat brain ; spinal cord ; raphe nuclei ; coexistence ; image analysis ; axoplasma flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Groups of male rats were treated for a period of 14 days with imipramine (10Μmol/kg) given twice daily. Separate groups of rats received a single dose treatment using the same dose and experimental design as for the repeated treatment. Employing the avidin-biotin immunoperoxidase technique for immunohistochemistry 5-hydroxytryptamine (5-HT)-, substance P (SP)- and thyrotropin releasing hormone (TRH)-like immunoreactivities (IRs) were visualized in consecutive coronal sections of the brain stem and of the spinal cord. The IRs were studied by means of morphometric and microdensitometric procedures using automatic image analysis on profiles representing nerve terminal networks of the ventral horn of the cervical and lumbar enlargements of the spinal cord as well as their coexistence (5-HT/SP and 5-HT/TRH). With the same technique 5-HT IR was measured in the 5-HT nerve cell groups of the medulla oblongata (B 1, B 2, B 3) and of the nucleus raphe dorsalis (B 7) of the midbrain. In addition 5-HT and 5-hydroxyindolacetic acid (5-HIAA) levels were measured in the ventral and dorsal horns of the cervical and lumbar enlargements of the spinal cord using high performance liquid chromatography (HPLC). In the same parts of the spinal cord SP IR was studied by means of radioimmunoassay (RIA). The microdensitometric studies showed that chronic, but not acute, imipramine treatment selectively increased SP IR in the 5-HT/SP/TRH costoring nerve terminals of the medial part of the ventral horn in both the cervical and the lumbar enlargements. Furthermore, quantitative analysis of the entity of coexistence in the 5-HT nerve terminal networks of these areas showed that all the 5-HT nerve terminals contained SP and TRH IRs and that this phenomenon remained after acute and chronic imipramine treatment. The microdensitometric studies on the 5-HT nerve cell groups of the medulla oblongata and of the nucleus raphe dorsalis demonstrated that chronic, but not acute, imipramine treatment selectively increased 5-HT IR in the nerve cell bodies of the lateral part of group B 3 as evaluated from the median grey values. Acute, but not chronic, imipramine treatment significantly increased the field area of 5-HT IR of nerve cell bodies in group B 7, reflecting an increase in the mean profile area of the 5-HT IR nerve cell body profiles. Instead, the mean profile area of 5-HT IR cell bodies of group B 1 was acutely reduced by imipramine. The biochemical studies demonstrated that chronic imipramine treatment selectively reduced 5-HT utilization in the ventral horn of the spinal cord and selectively increased SP IR in the dorsal horn of the lumbar enlargement. In view of these observations it is suggested that chronic imipramine treatment specifically increases SP IR in the 5-HT/SP/TRH costoring nerve terminals of the ventral horn probably related to reduced SP release and reduced 5-HT utilization in these terminals. The results obtained in group B 7 may be explained by a regulation by the3H-imipramine raphe binding sites of fast axonal transport, an influence which may have therapeutic consequences. This mechanism may also be responsible for the increase in 5-HT IR seen upon chronic imipramine treatment in the lateral part of the 5-HT nerve cell body group B 3. Such an effect may lead to a metabolic down-regulation of group B 7, having a possible role for the antidepressant activity of imipramine. The reduction of the mean profile area of 5-HT IR cell bodies of group B 1 seen in the acute treatment can possibly be caused by, noradrenaline (NA) uptake inhibition in inhibitory NA terminals innervating the B 1 group. These results also illustrate the heterogeneities in the responses of the 5-HT nerve cell groups to antidepressant treatment. The ability of chronic imipramine treatment to increase SP IR in the dorsal horn of the lumbar enlargement may reflect the existence of a monoamine-SP interaction in the substantia gelatinosa due to the NA and/or 5-HT uptake blocking activity of imipramine. The existence of such an interaction may help to explain the antinociceptive effect of chronic imipramine treatment.
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