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T Hedner

Publications and source records attributed to T Hedner.

9 recordsLinked to original sources
PubMed1979

Regional changes in monoamine synthesis in the developing rat brain during hypoxia.

4, 14 and 28 days old rats were exposed to hypoxic environment of 6% O2-94% N2 for 30 min. Tyrosine hydroxylase and tryptophan hydroxylase activity was studied in different brain regions (hemispheres, striatum, midbrain and brainstem in vivo by measuring the accumulation of dihydroxyphenylalanine (Dopa) and 5-hydroxytryptophan (5-HTP) respectively, after inhibition of aromatic L-amino acid decarobyxlase with NSD 1015. Tyrosine and tryptophan levels in the different brain regions were measured simultaneously. The tyrosine and tryptophan levels in the various brain parts were generally not influenced during exposure to hypoxia. Tyrosine hydroxylase activity decreased in most areas in the 4 and 14 days old rats, and all brain areas studied in the 28 days old rats. Tryptophan hydroxylase activity decreased markedly in all brain areas at all ages studied. It is concluded that the enzymes tyrosine hydroxylase as well as tryptophan hydroxylase seem to be equally affected during hypoxia in the different brain regions studied.

5-Hydroxytryptophan↗
PubMed1978

Effect of hypoxia on monoamine synthesis in brains of developing rats. III. Various O2 levels.

1-, 4-, 14- and 28-day-old rats were exposed to a hypoxic environment of 5.9, 8.0 or 12.0% O2 during a period of 30 min. In the brain, tyrosine hydroxylase and tryptophan hydroxylase activity was studied in vivo by measuring the accumulation of dihydroxyphenylalanine (DOPA) and 5-hydroxytryptophan (5-HTP), respectively, after inhibition of L-aromatic amino acid decarboxylase with NSD 1015. Tyrosine and tryptophan levels in the brain were measured simultaneously. The brain tyrosine and tryptophan levels were generally not influenced either by age or hypoxic levels. Tyrosine and tryptophan hydroxylase activity decreased to about the same extent during the various hypoxic levels at all ages studied. It is concluded that the first, rate-limiting, step in the synthesis of the monoamine neurotransmittors dopamine (DA), noradrenaline (NA) and 5-hydroxy-tryptophan (5-HT) is affected during moderate as well as severe hypoxia at all stages of development.

5-Hydroxytryptophan↗
PubMed1978

Effects of terbutaline on the pressure volume relationship in fetal rabbit lung.

The pressure-volume relationship in preterm rabbit lung was studied at 28 days of gestation. Injection of 0.1 mg terbutaline, a selective beta2-receptor stimulating drug, significantly increased the volume of air at equivalent low transpulmonary pressures, compared to a saline treated group and an untreated group. These findings indicate an increased pulmonary distensibility of the fetal rabbit lung after terbutaline administration. The mechanism of action is discussed and surfactant mediated effects are suggested to be the probable explanation.

Animals↗
PubMed1978

Antepartum administration of terbutaline and the incidence of hyaline membrane disease in preterm infants.

The incidence of hyaline membrane disease in 41 preterm infants born between January 1975 and January 1976 was investigated in a retrospective study. Terbutaline, a beta2-receptor stimulating drug, had been administered to the women in order to arrest premature labour. In spite of the treatment 24 preterm infants were delivered. The incidence of HMD in this group was 1/24. In a group of 17 neonates whose mothers had received no such treatment the incidence of HMD was 5/17. Comparison between the two groups revealed a significantly lower incidence of HMD in the terbutaline treated group than in the controls (p less than 0.05). There were no significant differences in maternal age, gestational age, birth weight or Apgar score between the two groups. The lower incidence of HMD in the terbutaline treated group is suggested to reflect a rapidly induced release of pulmonary surfactants in the preterm infants. Evidence for a similar sequence of events has earlier been shown to occur in animals under standardized experimental conditions.

Administration, Oral↗
PubMed1977

Effect of hypoxia on monoamine synthesis in brains of developing rats.

Tyrosine and tryptophan hydroxylase activity was studied in the postnatal rat brain in vivo by measuring the accumulation of dihydroxyphenylalanine and 5-hydroxytryptophan, respectively after inhibition of L-aromatic amino acid decarboxylase with NSD 1015. With increasing age there was a significant increase in the amount of dopa and 5-HTP accumulated in the brain after administration of NSD 1015. After 30 min in a 12% oxygen environment there were significant reductions of tyrosine hydroxylase and tryptophan hydroxylase activity at 1,14 and 28 but not 4 days of postnatal age. Further, the decrease in 5-HTP accumulation was significantly more marked at 14 and 28 days than at 1 day of age. Thus, the oxygen-dependent synthesis of the neurotransmitter 5-hydroxytryptamine seems to be less vulnerable in the early postnatal rat brain.

5-Hydroxytryptophan↗