Biomedical subjects

A Yuwiler

Publications and source records attributed to A Yuwiler.

At least 73 records · Page 4Linked to original sources

PubMed1977

Adrenergic control of pineal N-acetyltransferase activity: developmental aspects.

The activity of pineal N-acetyltransferase in the neonatal rat does not exhibit the large daily rhythm seen in the adult and is intermediate between the low day and high night adult values. These intermediate values appear to result from adrenergic stimulation. Blockade of adrenergic receptors or of catecholamine synthesis results in a decrease in enzyme activity in vivo. In vitro studies provide additional evidence of a completely developed postsynaptic adrenergic control system for pineal N-acetyltransferase activity at birth. Our observations indicate that the appearance of a circadian rhythm in pineal N-acetyltransferase at the end of the first week of life reflects the development of presynaptic mechanisms and structures necessary for the control of catecholamine release and uptake. These events follow the developmental appearance of the postsynaptic mechanisms required to mediate the adrenergic-cycle AMP regulation of pineal N-acetyltransferase activity, which can be detected prior to birth.

Acetyltransferases↗

PubMed1976

Effect of lithium and other alkali metals on brain chemistry and behavior. II. Intracranial self-stimulation behavior.

Rats implanted with bipolar electrodes aimed at the medial forebrain bundle (MFB) were trained to self-stimulate. Six daily injections of 2 mEq/kg of the chloride salts of Li+, Rb+ or Cs+ were administered and the rate of intracranial self-stimulation (ICSS) was recorded. Lithium caused a reversible decrease in ICSS rate, beginning on the second day and returning to pretreatment rate on the fourth day of injections. The decrease was more pronounced in animals with high baseline rate (over 500 responses/10 min) than in low responders. Rubidium enhanced ICSS rate whereas cesium had no effect. These results agree with other accumulating data showing the opposite effects of Li+ and Rb+, but their relevance to effective disorders is not clear.

Affective Symptoms↗

PubMed1976

Neonatal hydrocortisone: effect of the development of the stress response and the diurnal rhythm of corticosterone.

Neonatal rats were given s.c. injections of 1 mg of hydrocortisone acetate, and the effect on the subsequent development of the pituitary-adrenal response to ether stress and the development of the circadian rhythm in adrenal and serum corticosterone (B) was investigated. Following exposure to ether, adrenal steroids were elevated in 11-day-old controls. The response did not appear in treated animals until 25 days. At this age, the time-course of response to ether in the adrenal was more sluggish in hormone-treated rats. After stress, serum corticoids were high in controls at 20 days; however, this rise did not appear in treated rats until 25 days. Serum corticoids, 5-60 min after ether, tended to be lower in 25-day-old runts than in controls. The diurnal rhythm in serum B first appeared in controls at 27 days and in treated animals at 30 days. The rhythm in adrenal corticoids appeared in both groups at 30 days.

Age Factors↗

PubMed1975

Uptake and efflux of serotonin from platelets of autistic and nonautistic children.

This study examined, in vitro, the uptake and efflux of serotonin by platelets from autistic children, nonautistic hospitalized comparison cases, and normal children. The autistic patients were carefully selected according to previously established diagnostic criteria. The hospitalized comparison children were utilized to assess possible environmental and dietary influences upon the results. Uptake methods were similar to those used by previous investigators. Two efflux procedures were utilized to explore the possibility that methodological factors accounted for previously reported differences between autistic and comparison groups. The results failed to indicate statistically significant differences in uptake or efflux between the autistic and the hospitalized comparison groups or the normals. Methodologic considerations which could possibly account for the failure to confirm previous findings are discussed in detail.

Anticoagulants↗

PubMed1975

Effects of hydrocortisone on biogenic amine levels in the hypothalamus.

Implants of hydrocortisone acetate (HCA), cholesterol or empty tubing were placed in the hypothalamus of rats. Corticoid implants elevated serotonin levels in the basomedial hypothalamus compared to the other two groups, but norepinephrine levels were unchanged. Adrenal and serum cortcosterone, as well as adrenal weight, were lower in animals with hydrocortisone implants. These data support the hypothesis that hypothalamic serotonin is involved in negative feedback control of adrenal steroid secretion. Biogenic amines in the medial hypothalamus were determined at 30 days in rats neonatally treated with HCA. Both norepinephrine and serotonin levels were elevated significantly in the treated group in comparison to controls, but dopamine levels failed to change.

Adrenal Glands↗

PubMed1974