Effect of neonatal thyroid hormone alterations in CNS ethanol sensitivity in adult LS and SS mice.

LS and SS mice develop their differential sensitivity to the motor-incoordinating and hypothermic effects of ethanol at 10-16 days after birth, when thyroid hormones (T4) show a transient peak. This rise in the thyroid hormones is an important element in the normal development of monoaminergic systems and thyroid hormones reach a significantly higher level in the less ethanol-sensitive SS mice than in the more ethanol-sensitive LS mice. Previous investigation have suggested the differential ethanol response of brain monoaminergic neuronal systems in adult LS and SS mice may be related to this development difference in thyroid status. To test the hypothesis that neonatal thyroid status can influence adult CNS ethanol sensitivity. LS and SS mice were treated neonatally with the thyrotropin-releasing hormone (TRH) and propylthiouracil (PTU) to enhance or diminish, respectively, thyroid status at this critical developmental period. The subsequent effect on adult CNS ethanol sensitivity was then determined. Contrary to expectations, both PTU and TRH administration attenuated the transient rise in plasma T4 levels at postnatal days 10-16 in LS mice and in both instances this was associated with decreased CNS ethanol sensitivity (sleep time and hypothermia) in adults. In SS mice, PTU treatment attenuated the postnatal rise in T4 levels as expected, whereas TRH treatment had no significant effect. However, neither neonatal treatment altered CNS ethanol sensitivity in adult SS mice. The decrease in ethanol-induced sleep times and hypothermia of neonatally treated LS mice was associated with an attenuation of ethanol-induced decreases in in vivo tyrosine and tryptophan hydroxylase activity that was not seen in the SS mice. These findings are consistent with the notion that the response of monoaminergic neuronal systems to ethanol is an important determinant of behavioral intoxication. However, the observation that neonatal administration of both TRH and PTU blunted the postnatal rise in thyroid levels in LS mice, yet both treatments resulted in a decrease in adult ethanol sensitivity in LS mice, indicates that the relationship between postnatal thyroid development and CNS ethanol sensitivity is more complex than originally hypothesized.

Development of neurochemical and behavioral sensitivity to ethanol in long-sleep and short-sleep mice.

The postnatal development of certain neurochemical correlates of CNS ethanol sensitivity was examined in the long-sleep (LS) and short-sleep (SS) mice. The differences in sensitivity to the motor-incoordinating and hypothermic effects of ethanol emerged during the second and third weeks of life. Prior studies have shown the sleep time differences between LS and SS mice became significant at 8-10 days of age whereas the present results established that the differences in ethanol-induced hypothermia became prominent at 12-16 days of age. Previous results from our laboratory suggested that the greater CNS ethanol behavioral sensitivity (sleep time and hypothermia) of LS mice is related to the greater ethanol-induced depression of brain monoamine synthesis in the LS line. The timing of the developmental changes in neurochemical ethanol sensitivity in LS and SS mice was found to parallel that found in the development of behavioral ethanol sensitivity as follows. Ethanol-induced decreases in in vivo tyrosine hydroxylase activity in the cerebellum, hypothalamus, and brain stem did not differ between LS and SS mice at postnatal day 8, but became substantially greater in LS mice between postnatal days 8 and 12, coincident with the appearance of the greater sleep times of LS mice. Likewise, ethanol-induced decreases in in vivo tryptophan hydroxylase activity in the dorsal raphe and hypothalamus, which were similar in LS and SS mice at postnatal days 8 and 12, became significantly greater in LS mice by postnatal day 16, the age at which their increased sensitivity to ethanol-induced hypothermia appeared.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of thyrotropin-releasing hormone and catecholaminergic interactions on CNS ethanol sensitivity.

The role of catecholamine neuronal systems in mediating the analeptic and thermogenic effects of thyrotropin-releasing hormone (TRH) was examined in long-sleep (LS) and short-sleep (SS) mice. TRH [0.1 to 40 micrograms, intracerebroventricularly (icv)] was associated with a reduction in the sleep times of LS mice, but no dose of TRH had any effect on sleep times of SS mice. However, TRH (20 micrograms, icv) produced a 1.0 degree to 1.5 degrees C attenuation of the ethanol-induced hypothermia in both LS and SS mice. TRH did not change the rate of ethanol elimination in either line of mice, suggesting that the reduction in LS sleep times and attenuation of LS and SS hypothermia were due to decreased CNS ethanol sensitivity rather than an increase in the rate of ethanol metabolism. TRH (20 micrograms, icv) given alone produced an activation of central and peripheral catecholamine systems in LS, but not SS mice, as reflected by an increase in the in vivo tyrosine hydroxylase (TH) activity in the brain and adrenal gland. TRH, given with ethanol, prevented or attenuated ethanol-induced decreases in the brain and adrenal gland in vivo TH activity in LS mice but not SS mice. Thus, there was an association between the ability of TRH to produce an activation of catecholamine neuronal systems (increased rate of catecholamine biosynthesis) and the analeptic action of TRH to reduce the CNS depressant effects of ethanol (decreased sleep times).(ABSTRACT TRUNCATED AT 250 WORDS)

Serotoninergic involvement in ethanol-induced alterations of thermoregulation in long-sleep and short-sleep mice.

The effect of ethanol and pentobarbital on in vivo tryptophan hydroxylase activity and its relationship to drug-induced alterations of thermoregulation was examined in long-sleep (LS) and short-sleep (SS) mice. Serotonin function was measured in both the presence and absence of ethanol or pentobarbital in six discrete brain regions. Differences in basal levels of serotonin, 5-hydroxyindole acetic acid or in vivo tryptophan hydroxylase (TpH) activity were found only in the hypothalamus and dorsal raphe nuclei (SS slightly higher). Ethanol (4.2 g/kg i.p) caused significant reductions in in vivo TpH activity in the dorsal and pontine-medullary raphe nuclei and hypothalamus (putative thermoregulatory areas) in both LS (50-60% decrease) and SS (15-30% decrease) mice, but it had no effect on TpH activity in the striatum, cortex or hippocampus. The greater degree of ethanol-induced reduction in TpH activity in LS mice was associated with a greater degree of hypothermia (LS, 4.2 degrees C vs SS, 2.0 degrees C). Pentobarbital had equivalent effects in LS and SS mice on TpH activity in central nervous system thermoregulatory areas (decreases of 40-60%) and on body temperature (decreases of 6.8-7.5 degrees C). When the mice were given ethanol at an elevated environmental temperature (34 degrees C) the hypothermia was almost abolished completely, but depressant effects on TpH activity remained, suggesting that ethanol-induced decreases in TpH activity were direct effects and not secondary to hypothermia. Alterations in ethanol or pentobarbital elimination did not appear to account for the observed differences.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential effects of norepinephrine on phosphatidylinositol 4,5-bisphosphate stimulated hydrolysis in brains of mice genetically selected for differences in ethanol sensitivity.

The effects of norepinephrine on phosphoinositide turnover were evaluated in five brain regions of the long sleep (LS) and short sleep (SS) mice. These mice were selectively bred for differences in central nervous system sensitivity to ethanol with the LS exhibiting much greater sensitivity to a hypnotic dose of ethanol than the SS, as determined by the ability of the mice to regain their righting reflex. Norepinephrine (10(-3) M, 10(-4) M, and 10(-5) M) significantly increased phosphoinositide turnover in the hippocampus, hypothalamus, locus ceruleus, cerebellum, and cortex within each line of mice. Basal and norepinephrine-stimulated phosphoinositide turnover were significantly higher in the SS mice as compared with the LS mice in the cerebellum and cortex but not the other brain regions. Incorporation of 3H-inositol into 3H-phosphatidylinositols was not different between SS and LS mice in the cerebellum and cortex. The greater norepinephrine-stimulated phosphoinositide turnover in the cerebellum and cortex of the SS versus the LS mice may contribute to the CNS sensitivity to ethanol in these two lines of mice. However, ethanol (500 mM) had no effect on basal or norepinephrine-stimulated phosphoinositide turnover in any of the five brain areas examined in the LS and SS mice.

Carbon fibre composite bone plates. Development, evaluation and early clinical experience.

We compared the mechanical properties of carbon fibre composite bone plates with those of stainless steel and titanium. The composite plates have less stiffness with good fatigue properties. Tissue culture and small animal implantation confirmed the biocompatibility of the material. We also present a preliminary report on the use of the carbon fibre composite plates in 40 forearm fractures. All fractures united, 67% of them showing radiological remodelling within six months. There were no refractures or mechanical failures, but five fractures showed an unexpected reaction; this is discussed.

Role of brain tyrosine availability in mediating differences in ethanol sensitivity in long-sleep and short-sleep mice.

Long-sleep (LS) and short-sleep (SS) mice, bred for differences in initial sensitivity to ethanol, were found to differ considerably in the effect of ethanol on brain tyrosine levels. Brain tyrosine levels are decreased in both lines of mice over a 120-min period after ethanol, but the onset of the decrease occurs earlier (15 min vs. 60 min) and the extent of the decrease is greater (39% vs. 18%) in LS mice. This phenomenon is apparently related to the greater central nervous system ethanol sensitivity of LS mice, inasmuch as prior administration of tyrosine will prevent the ethanol-induced decrease in brain tyrosine levels and result in a decrease in the ethanol-induced sleep times of LS mice. An earlier study suggested a relationship between decreased catecholamine turnover in certain brain regions of LS mice and their greater ethanol sensitivity. The present observation that tyrosine pretreatment prevents or attenuates these ethanol-induced decreases in catecholamine turnover, while ethanol sensitivity is reduced, provides additional support for this apparent relationship. If the mice are pretreated with agents (large neutral amino acids) that lower brain tyrosine, the ethanol sensitivity (sleep times) increases in both lines of mice. The increased sensitivity is associated with marked decreases in brain region catecholamine turnover in both the LS and SS mice. These results are consistent with a role for catecholamine neuronal systems in mediating some of the intoxicating actions of ethanol, in general, and the differences in LS/SS ethanol sensitivity in particular.

Further studies on the neurochemical mechanisms mediating differences in ethanol sensitivity in LS and SS mice.

Long-sleep (LS) and short-sleep (SS) lines of mice were selectively bred for differences in CNS sensitivity to ethanol with LS mice exhibiting much greater sensitivity to hypnotic doses of ethanol (4.0-4.5 g/kg) than SS mice. The influence of peripheral and central catecholamine neuronal systems on ethanol sensitivity (sleep time) in LS and SS mice was examined following administration of reserpine, alpha-methyl-p-tyrosine and 6-hydroxydopamine. Ten days after a single dose of reserpine, tyrosine hydroxylase activity was increased in the brain and adrenal gland of LS mice but only in the brain of SS mice relative to untreated mice. Brain catecholamine levels in the reserpine-treated mice were 25-50% lower in both LS and SS mice compared to levels in untreated mice. These changes were associated with a 41% reduction in LS sleep time, but a 90% increase in SS sleep time. SS mice were also more susceptible to the lethal effects of reserpine. The increased mortality of SS mice may relate to a greater degree of reserpine-induced hypothermia and a slower rate of recovery of brain catecholamine levels. Neonatal LS and SS mice treated with 6-hydroxydopamine exhibited increased levels of catecholamines in the locus ceruleus, decreased levels in the cerebellum and unchanged levels in the hypothalamus at 60 days of age. These changes were associated with a modest decrease (10%) in LS sleep time and a marked increase (200%) in SS sleep time. alpha-Methyl-p-tyrosine decreased brain catecholamine levels of both lines by 30-50% while LS sleep times were unchanged and SS sleep times were increased by 45%.(ABSTRACT TRUNCATED AT 250 WORDS)

Foamy myocardial transformation of infancy: an inherited disease.

Five cases of foamy myocardial transformation of infancy, a condition which predominantly affects female children under 2 years of age and which causes cardiac arrhythmia or sudden death, are reported. Of these five cases, four occurred in two sets of siblings, suggesting a possible hereditary basis for the disease. As far as we know, no other familial cases have been reported. The other case was of focal disease of the myocardium, as opposed to the diffuse myocardial changes seen in the four familial cases.

Alpha-methyl-para-tyrosine effects in mice selectively bred for differences in sensitivity to ethanol.

The responses of catecholamine systems in long sleep (LS) and short sleep (SS) mice to alpha-methyl-p-tyrosine (AMPT) have been examined. Marked differences were found between LS and SS mice in the dose necessary for maximal brain catecholamine depletion and in the time-course of the catecholamine depletion. Brain catecholamines in the LS mice were depleted by lower doses of AMPT and the levels remained depressed for longer periods of time in this line of mice. These differences may be explained only partially by an increased susceptibility of the LS mice to the hypothermia and toxic effects caused by AMPT administration, as they persist with non-toxic AMPT dosage regimens and under conditions where the degree of hypothermia is comparable in both lines of mice. In addition, there were no differences between the Ki values for the effect of AMPT on the tyrosine hydroxylase from striata of these mouse lines. The primary cause of the heightened response to AMPT in LS mice would appear to be pharmacokinetic in nature, as brain and plasma peak levels of AMPT in LS mice were greater and the levels remained higher for a longer time. The depletion of brain tyrosine by AMPT combined with the lower affinity of the LS striatal tyrosine hydroxylase for the substrate tyrosine may also contribute to the heightened response in LS mice.

Ethanol-induced changes in tyrosine hydroxylase activity in adrenal glands of mice selectively bred for differences in sensitivity to ethanol.

In the present study catecholaminergic systems in the adrenal glands of mice selectively bred for differences in sensitivity to ethanol, the long-sleep (LS) and short-sleep (SS) mice, have been examined. Tyrosine hydroxylase (TH) activity and catecholamine levels were measured in the adrenal glands at various times after a single injection of ethanol (4.0 g/kg i.p.). Basal levels of TH activity, epinephrine and norepinephrine are significantly higher in the adrenal glands of LS mice by 87, 20, and 26%, respectively. Ten minutes after ethanol administration, LS mouse adrenal gland TH activity is decreased by 33% whereas SS mouse adrenal gland TH activity is increased by 68%. At 25 and 125 min after ethanol, SS mouse adrenal gland TH activity is no longer increased, but the decrease in TH activity persists in adrenals of LS mice. The corresponding adrenal gland catecholamine levels are unchanged in the LS and SS mice at all times measured except at 125 min in LS mice when both epinephrine (24%) and norepinephrine (31%) are decreased. The increase in SS adrenal gland TH activity at 10 min after ethanol administration is associated with an increase in the affinity of the enzyme for the pterin cofactor (decreased Km). Conversely, the decrease in TH activity at 10 min after ethanol in LS mice is associated with an increase in Km for the pterin cofactor. The Vmax is unchanged by ethanol treatment in either line. Prior administration of chlorisondamine (15 mg/kg i.p.) has no effect on either the ethanol-induced changes in adrenal gland TH activity at 10 min or the sleep time of LS mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of ethanol on tyrosine hydroxylation in brain regions of long and short sleep mice.

The effect of ethanol on the in vivo rate of tyrosine hydroxylation in 6 brain regions was examined in two lines of mice selectively bred for a differential sensitivity to ethanol. The mice are designated long-sleep (LS) and short-sleep (SS) and lose their righting reflex for a duration of 100 minutes (LS) and 13 minutes (SS) following an intraperitoneal dose of ethanol of 4.0 g/kg. DOPA accumulation after NSD-1015 administration was measured in the absence and presence of ethanol (4.0 g/kg, IP) in the periods 5-35 minutes and 85-115 minutes after saline or ethanol. There were no differences between the lines in either basal catecholamine levels or basal tyrosine hydroxylation rates (as measured by DOPA accumulation) in any brain region except the cerebellum, where the norepinephrine content in the SS mice is 33% greater and the tyrosine hydroxylation rate is 25% higher than that in the LS mice. In the presence of ethanol, there was a differential effect on the in vivo tyrosine hydroxylation rate. In the cerebellum of both LS and SS mice there was a decreased rate of tyrosine hydroxylation in the early period after ethanol, but the rate in the cerebellum of SS mice returned to the control value at 85-115 min. At that time, the rate in LS mice is still decreased. In the locus ceruleus, hypothalamus and frontal cortex, ethanol has no effect on the rate of tyrosine hydroxylation in either LS or SS mice during the early period, but ethanol decreases the rate during the later period in the LS mice only.(ABSTRACT TRUNCATED AT 250 WORDS)

Disposition of (R,S)-tocainide. Some stereoselective aspects.

We have undertaken to study the stereoselective disposition of (R,S)-tocainide, a new antiarrhythmic agent. To determine the enantiomeric composition of tocainide extracted from urine or blood serum, the drug was converted to diastereomeric derivatives by reaction with (S)-alpha-methoxy-alpha-trifluoromethylphenylacetyl chloride, and the diastereomers were separated by gas chromatography. The stereoselective excretion of tocainide in the 24-hr urine of male and female rats and mice was studied after 20-mg/kg ip doses of the racemic drug. The (R)/(S) ratio of excreted drug was greater than 1.0 in mice and less 1.0 in rats. Sex differences were also found. Pretreatment with phenobarbital significantly reduced the excretion of the (S) isomer in male and female mice and in male rats, and significantly reduced the excretion of the (R) enantiomer in male rats only. The (R)/(S) ratio of circulating tocainide in the serum of patients receiving the drug was significantly different from 1.0 in several samples analyzed. The reduction of 2-oxopropiono-2',6'-xylidide, the product of the oxidative deamination of tocainide, to 2-hydroxypropiono-2',6'-xylidide, a known circulating metabolite of tocainide in humans, was catalyzed by rabbit- and rat-liver cytosol, and the reduction proceeded with high stereoselectivity to give predominantly or exclusively the (S)-alcohol.