Effect of biogenic amines reuptake inhibition on ethanol induced hypothermia

Ethanol-induced hypothermia in rats is antagonized by dexamethasone

The effect of dexamethasone on ethanol-induced hypothermia was investigated in 3.5-month old male Wistar rats (N = 10 animals per group). The animals were pretreated with dexamethasone (2.0 mg/kg, i.p.; volume of injection = 1 ml/kg) 15 min before ethanol administration (2.0, 3.0 and 4.0 g/kg, i.p.; 20% w/v) and the colon temperature was monitored with a digital thermometer 30, 60 and 90 min after ethanol administration. Ethanol treatment produced dose-dependent hypothermia throughout the experiment (-1.84 +/- 0.10, -2.79 +/- 0.09 and -3.79 +/- 0.15 degrees C for 2.0, 3.0 and 4.0 g/kg ethanol, respectively, 30 min after ethanol) but only the effects of 2.0 and 3.0 g/kg ethanol were significantly antagonized (-0.57 +/- 0.09 and -1.25 +/- 0.10, respectively, 30 min after ethanol) by pretreatment with dexamethasone (ANOVA, P < 0.05). These results are in agreement with data from the literature on the rapid antagonism by glucocorticoids of other effects of ethanol. The antagonism was obtained after a short period of time, suggesting that the effect of dexamethasone is different from the classical actions of corticosteroids.

Fluoxetine. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in depressive illness

Fluoxetine is a new antidepressant which enhances serotoninergic neurotransmission through potent and selective inhibition of neuronal reuptake of serotonin. Metabolism by N-desmethylation occurs in man yielding desmethylfluoxetine, which also inhibits serotonin reuptake. Both the parent compound and metabolite possess elimination half-lives of several days facilitating the maintenance of steady-state plasma concentrations during long term treatment. Fluoxetine has overall therapeutic efficacy comparable with imipramine, amitriptyline and doxepin in patients with unipolar depression treated for 5 to 6 weeks, although it may be less effective than tricyclic antidepressants in relieving sleep disorders in depressed patients. Geriatric patients also responded as well to fluoxetine as to doxepin. The symptomatic improvement in patients with unipolar depression during short term fluoxetine treatment has been satisfactorily maintained when therapy was extended for at least 6 months: the relapse rate was low and similar to that of imipramine. Preliminary data have shown that patients with bipolar depression gained similar therapeutic benefit from fluoxetine or imipramine. Other preliminary trials have indicated that fluoxetine may be useful in obsessive-compulsive disorders. Usual doses of fluoxetine cause significantly fewer anticholinergic-type side effects than tricyclic antidepressants. Nausea, nervousness and insomnia are the most frequently reported fluoxetine-related adverse effects, but these have usually not been severe. Therapeutic doses of fluoxetine do not affect cardiac conduction intervals in patients without pre-existing cardiovascular disease and fluoxetine has been relatively safe in the small number of patients who have taken overdoses. It has not been clearly established whether some types of depression may respond more readily to fluoxetine than other antidepressants, and its overall therapeutic efficacy has not been compared with other second generation antidepressants. Thus, with its different and perhaps improved side effect profile compared with older tricyclic antidepressants, fluoxetine offers properties that could be used to advantage in many patients with depression.

Changes in body temperature after administration of adrenergic and serotonergic agents and related drugs including antidepressants: II

This survey continues a second series of compilations of data regarding changes in body temperature induced by drugs and related agents. The information listed includes the species used, the route of administration and dose of drug, the environmental temperature at which experiments were performed, the number of tests, the direction and magnitude of change in body temperature and remarks on the presence of special conditions, such as age or brain lesions. Also indicated is the influence of other drugs, such as antagonists, on the response to the primary agent. Most of the papers were published from 1980 to 1984 but data from many earlier papers are also tabulated.

Release of norepinephrine from the rat's hypothalamus perfused with alcohol: relation to body temperature

The activity of norepinephrine (NE) within the thermosensitive region of the anterior hypothalamic, pre-optic area (AH/POA) of the rat was examined in relation to changes in core temperature produced by ethyl alcohol. Following stereotaxic implantation of push-pull guide tubes, a specific site in the AH/POA, reactive or non-reactive to NE, was labeled with 1.0 microliter of [3H]-NE. Alcohol in a concentration of 2.75% or 5.5% was then perfused locally at the same site by push-pull cannulae or administered peripherally in a dose of 2.0 g/kg. In control experiments, artificial CSF was perfused alone. The perfusion of alcohol enhanced or delayed the release of [3H]-NE in AH/POA or failed to alter the efflux of the catecholamine, with the specific response dependent principally on the: (1) anatomical site of hypothalamic perfusion, (2) concentration of alcohol, and (3) interval of perfusion itself. During the perfusion of alcohol within a very circumscribed region in the AH/POA, vasodilatation, as reflected by an increase in skin temperature, and a hypothermia of short latency, occurred. The change in core temperature was usually accompanied by a delay in the efflux of [3H]-NE. After the peripheral administration of 2.0 g/kg alcohol, an alteration in NE efflux from the AH/POA was also induced during the course of a hypothermic response accompanied by vasodilatation. These results suggest that alcohol exerts a direct central effect on nerve cells comprising the thermoregulatory mechanism located within the hypothalamus. Further, the well-known thermolytic effect of alcohol could be mediated in part by noradrenergic synapses within AH/POA, by means of their phasic release of NE.

Effects of methamphetamine and methyldopa on ethanol induced hypothermia in mice

The effects of D-methamphetamine HCl (1, 2 and 4 mg/kg, i.p.) and alpha-methyldopa (1, 2 and 4 mg/kg, i.p.) on rectal temperature and on ethanol (3 g/kg, i.p.)-induced hypothermia have been investigated in mice. Methamphetamine caused a dose-dependent hyperthermia, but methyldopa induced hypothermia, which decreased with increases in dose. Methamphetamine antagonized the hypothermic effect of ethanol, but methyldopa (1 and 2 mg/kg) did not affect it. Methyldopa (4 mg/kg), however, reversed ethanol hypothermia. Ethanol pretreatment significantly potentiated the hypothermic effect of methyldopa (4 mg/kg), and it prevented methamphetamine-induced hyperthermia. A possible central action for the tested drugs on biogenic monoamines and a peripheral component in their thermoregulatory effects are discussed in this report.