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81.
In this article, we discuss molecular mechanisms involved in the evolution of amygdala kindling and the episodic loss of response
to pharmacological treatments during tolerance development. These phenomena allow us to consider how similar principles (in
different neurochemical systems) could account for illness progression, cyclicity, and drug tolerance in affective disorders.
We describe the phenomenon of amygdala-kindled seizures episodically breaking through effective daily pharmacotherapy with
carbamazepine and valproate, suggesting that these observations could reflect the balance of pathological vs compensatory
illness-induced changes in gene expression. Under certain circumstances, amygdala-kindled animals that were initially drug
responsive can develop highly individualized patterns of seizure breakthroughs progressing toward a complete loss of drug
efficacy. This initial drug efficacy may reflect the combination of drug-related exogenous neurochemical mechanisms and illness-induced
endogenous compensatory mechanisms. However, we postulate that when seizures are inhibited, the endogenous illness-induced
adaptations dissipate (the “time-off seizure” effect), leading to the re-emergence of seizures, a re-induction of a new, but
diminished, set of endogenous compensatory mechanisms, and a temporary period of renewed drug efficacy. As this pattern repeats,
an intermittent or cyclic response to the anticonvulsant treatment emerges, leading toward complete drug tolerance.
We also postulate that the cyclic pattern accelerates over time because of both the failure of robust illness-induced endogenous
adaptations to emerge and the progression in pathophysiological mechanisms (mediated by long-lasting changes in gene expression
and their downstream consequences) as a result of repeated occurrences of seizures. In this seizure model, this pattern can
be inhibited and drug responsivity can be temporarily reinstated by several manipulations, including lowering illness drive
(decreasing the stimulation current.), increasing drug dosage, switching to a new drug that does not show crosstolerance to
the original medication, or temporarily discontinuing treatment, allowing the illness to re-emerge in an unmedicated animal.
Each of these variables is discussed in relation to the potential relevance to the emergence, progression, and suppression
of individual patterns of episodic cyclicity in the recurrent affective disorders. A variety of clinical studies are outlined
that specifically test the hypotheses derived from this formulation. Data from animal studies suggest that illness cyclicity
can develop from the relative ratio between primary pathological processes and secondary endogenous adaptations (assisted
by exogenous medications). If this proposition is verified, it further suggests that illness cyclicity is inherent to the
neurobiological processes of episode emergence and amelioration, and one does not need to postulate a separate defect in the
biological clock. The formulation predicts that early and aggressive long-term interventions may be optimal in order to prevent
illness emergence and progression and its associated accumulating neurobiological, vulnerability factors. 相似文献
82.
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H. James Spooner 《CMAJ》1996,154(12):1875-1876
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H.U. Schweikert U.W. Tunn U.-F. Habenicht J. Arnold Th. Senge H. Schulze F.H. Schrder J.H.M. Blom O. Ennemoser W. Horniger G. Bartsch 《The Journal of steroid biochemistry and molecular biology》1993,44(4-6):573-576
Sex steroids are thought to play an essential role in the pathogenesis of human benign prostatic hyperplasia (BPH). Since recent studies in animal models and in men have shown that estrogens might be causally linked to the onset and maintenance of BPH, we examined the effect of 1-methyl-androsta-1,4-diene-3,17-dione (Atamestane), a newly developed aromatase inhibitor, in men with BPH. In an open multicenter study 49 men (mean age 70.1 years, range 55 to 84) with obstructive BPH were treated with atamestane (3 × 200 mg/day) for 3 months. Of the 49 patients 44 completed the treatment period; the other patients discontinued the study for reasons unrelated to treatment. With treatment BPH-related symptoms such as daytime voiding frequency, nycturia, peak flow and residual urine improved considerably; however, these parameters did not reach statistical significance. The mean prostatic volume decreased significantly from 74.2 ± 31.7 to 64.0 ± 31 ml (mean ± SD). Serum estrogen levels decreased markedly during treatment. In addition intraprostatic estrogen concentration decreased with treatment as compared to estrogen levels in hyperplastic prostates from untreated patients. The following conclusions can be drawn from this study: first, estrogens appear to have an important supportive role in established BPH, and second, estrogen deprivation improved BPH-related symptoms and reduced significantly prostatic volume. 相似文献
90.
Growth and Osmotic Adjustment of Cultured Suspension Cells from Alternanthera philoxeroides (Mart.) Griseb After an Abrupt Increase in Salinity 总被引:2,自引:0,他引:2
BALAGTAS-BUROW GLORIA E.; MORONEY JAMES V.; LONGSTRETH DAVID J. 《Journal of experimental botany》1993,44(3):673-679
We have developed a cell suspension culture from alligator weed(Alternanthera philoxeroides [Mart.] Griseb), a C3 member ofthe Amaranthaceae. Intact plants of alligator weed can growat 400 mol m3 NaCl. Growth of alligator weed suspensionswas compared to growth of tobacco (Nicotiana tabacum L. cv.Wisconsin 38) suspensions after subculture to 200 mol m3NaCl. Fresh weight and cell density of salt-treated alligatorweed suspensions more than doubled by 7 d after subculture,but the fresh weight of salt-treated tobacco suspensions didnot double during the 21 d experiment. Correspondingly, cellviability dropped from about 90% to 77% in alligator weed andto 41% in tobacco, at 1 d after subculture to 200 mol m3NaCl. The symplastic volume of alligator weed cells declined36% by 2 h after subculture to 200 mol m3 NaCl, but cellcontents became iso-osmotic with the media at this point. Between2 h and 6 h there was a further decrease in osmotic potential,an increase in turgor potential and a partial recovery of symplasticvolume. Turgor potential was similar to that in control cellsby 24 h, indicating significant osmotic adjustment. Turgor potentialsremained similar in both treatments from 24 h through 21 d butthe average symplastic volume of salt-treated cells was 11 %less than in control cells. Therefore, alligator weed suspensioncells exhibit a rapid recovery of water balance and cell growthafter an abrupt and substantial increase in salinity. Key words: Cell culture, growth, osmotic adjustment, salinity, turgor potential 相似文献