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Biomedical subjects

W W Morgan

Publications and source records attributed to W W Morgan.

At least 91 records · Page 5Linked to original sources
PubMed1978

Elevation of serum prolactin levels after the inhibition of serotonin uptake.

Although earlier investigators showed that serotonin produced an elevation in serum PRL, recent studies indicate that serotonergic mechanisms are not of importance, at least in older adult animals, in the tonic regulation of serum PRL levels. As the activity of neuronal pathways may vary in activity at different chronological ages, the present study was undertaken to further evaluate the role of serotonergic pathways in the regulation of serum PRL levels. During the course of the study, animals in two different weight ranges were studied. In the initial studies, young male rats in the 120- to 170-g range were studied, while in later studies male rats in the 250-340-g weight range were utilized. In rats weighing 120-170 g, the administration of fluoxetine (Lilly 110140), an inhibitor of serotonin uptake, produced a significant elevation of serum PRL which persisted for at least 8 h. At the same time, diencephalon 5-hydroxyindoleacetic acid levels were decreased, providing evidence of the effectiveness of the drug treatment. Methysergide completely blocked the effect of fluoxetine and markedly suppressed serum PRL concentration. In agreement with the results of others, fluoxetine did not produce an increase in serum PRL in older male rats (250-340 g). However, fluoxetine seemed to suppress the circadian elevation of serum PRL in these older rats. These data provide evidence that serotonergic pathways may be of more importance in the tonic regulation of serum PRL in young male Sprague-Dawley rats. The specific pathways involved cannot be determined from these studies.

Aging↗
PubMed1976

Comparison of changes in tryptophan and serotonin in regions of the hamster and the rat brain over a twenty-four hour period.

Groups of male golden hamsters and Sprague-Dawley rats were sacrificed at 4-h intervals over a 24-h period. Tryptophan and serotonin (5-HT) were measured in the telencephalon and brain stem and tryptophan was measured in serum. Highly statistically significant changes in tryptophan and 5-HT content were observed over the period of the day. Generally the changes were more clearly defined and were significant to a higher statistical level in the hamster than in the rat. Statistically significant changes were also observed in serum tryptophan. In the hamster the daily changes in serum tryptophan were coincidental with similar changes in tryptophan and 5-HT in the brain stem and tryptophan in the telencephalon. On the other hand, the changes in 5-HT in the hamster telencephalon were not well correlated with changes in tryptophan and serum tryptophan.

Animals↗
PubMed1976

Increased rate of disappearance of serum probenecid in barbital dependent rats.

Rats were made barbital dependent by administration of barbital in their drinking water. Subsequently, the rats were either not withdrawn (BN) or withdrawn from barbital for 24 h (BW-24). Before sacrifice, probenecid was administered to measure brain serotonin turnover. A statistically significant decrease in 5-hydroxyindoleacetic acid (5-HIAA) accumulation was observed in the cerebral cortex medulla pons and midbrain. Subsequentialy, serum levels of probenecid were also measured by gas chromatography to determine if chronic barbital consumption might affect circulating probenecid. By ninety minutes following probenecid administration, serum probenecid levels in BN and BW-24 rats were significantly lower than control while a probenecid metabolite was significantly increased. The significantly reduced accumulation of 5-HIAA in brain areas of BN and BW-24 rats is probably the result of the more rapid decline of probenecid rather than a true decrease in serotonin turnover.

Animals↗