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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Partial hemitransection at the mesodiencephalic junction in the rat increased striatal and nigral putrescine concentrations on the lesioned side for at least 168 h, with maximal increases between 24 and 48 h. Spermidine and spermine levels declined at 24 h in the striatum, rising above control values at 48 h and further at 168 h. In the substantia nigra, they remained unchanged for the first 48 h and then increased by 168 h. Cadaverine in the striatum also increased at 48 h. On the intact side putrescine increased but to a much lesser extent (at 48 h in the striatum and at 24 and 48 h in the substantia nigra). Ornithine decarboxylase and diamine oxidase activities showed maximal increases at 24 h in the striatum of the lesioned side, whereas in the substantia nigra ornithine decarboxylase attained a very high value as early as 4 h after the operation and diamine oxidase activity peaked at 48 h. The enzyme activities returned toward the basal values at 168 h. On the intact side, ornithine decarboxylase showed a small increase starting at 4 h and diamine oxidase was enhanced at 48 h. These results indicate that the stimulation of biosyn-thetic and degradative enzymes of polyamine metabolism accompanied by marked and prolonged increases in putrescine may be essential events in the early phases of neuronal response to mechanical injury in the CNS.
    Type of Medium: Electronic Resource
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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 Diestrous female rats were exposed to the smoke from one to four cigarettes. Exposure to unfiltered cigarette smoke produced dose- and time-dependent reductions of catecholamine levels and dose- and time-dependent increase in catecholamine utilization in the various hypothalamic and preoptic dopamine and noradrenaline nerve terminal systems. These effects were counteracted by pretreatment with the ganglion blocking agent mecamylamine (1 mg/kg). Exposure to cigarette smoke was also found to produce a dose- and time-dependent inhibition of serum prolactin, LH and FSH levels which was counteracted by pretreatment with mecamylamine. Exposure to the smoke from one cigarette (but not from four cigarettes) increased serum TSH levels. In combination with tyrosine hydroxylase inhibition the exposure to cigarette smoke produced a dose- and time-dependent inhibition of plasma ACTH levels, an action which was counteracted by pretreatment with mecamylamine. The results demonstrated a sex difference (cf. Andersson et al. 1985c), in the nicotine-induced changes of TSH and ACTH secretion despite a general increase in hypothalamic and preoptic dopamine and noradrenaline utilization in both the male and the diestrous female rat. The differences in the neuroendocrine actions of acute intermittent exposure to cigarette smoke in the diestrous rat and the normal male rat are discussed.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1912
    Keywords: Nicotine ; Cigarette smoke ; Withdrawal ; Hypothalamus ; Noradrenaline ; Dopamine ; Amine turnover ; Adenohypophyseal hormones ; Vasopressin ; Corticosterone ; Testosterone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 48 h but not a 72 h or 7 day withdrawal from chronic exposure to cigarette smoke was associated with increased noradrenaline levels (quantitative histofluorimetry) in the subependymal layer (SEL) of the median eminence, the anterior periventricular hypothalamic region (PV I) and the parvocellular part of the hypothalamic nucleus (PA FP) and an increased noradrenaline utilization (tyrosine hydroxylase inhibition by αMT) in the SEL and the PV I. Following a 48 h or 72 h but not a 7 day withdrawal from chronic exposure to cigarette smoke an increased catecholamine utilization was found in the medial palisade zone (MPZ) of the median eminence. Reduced serum prolactin, FSH and corticosterone levels were found following a 48 h withdrawal from chronic exposure to cigarette smoke. Following a 72 h withdrawal from chronic exposure to cigarette smoke a reduced concentration of serum prolactin was noted. Chronic exposure to cigarette smoke reduced serum TSH levels and lead to a tolerance development with regard to noradrenaline levels and utilization within the preoptic region with the exception of the periventricular preoptic region. The finding of special interest in the present study is the demonstration of a highly significant lowering of corticosterone serum levels despite maintained blood levels of ACTH as seen 48 h following withdrawal. It is suggested that this type of endocrine change may lead to changes in fear-motivated behaviour and contribute to behavioural withdrawal reactions. The maintained reductions of serum prolactin levels found after 48 h and 72 h of withdrawal from cigarette smoke exposure (cf. Andersson et al. 1985a) is discussed in terms of an increased catecholamine utilization in the medial palisade zone of the median eminance. This activation is suggested to be caused by the development of a prolactin receptor supersensitivity within the medium eminence. The present evidence indicates withdrawal effects mainly in the noradrenaline nerve terminals of the sub-ependymal layer of the median eminence, the anterior periventricular hypothalamic region and the parvocellular part of the paraventricular hypothalamic nucleus which inter alia are involved in regulation of ACTH secretion (cf. Andersson et al. 1985a).
    Type of Medium: Electronic Resource
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