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Biomedical subjects

E Geller

Publications and source records attributed to E Geller.

At least 109 records · Page 6Linked to original sources
PubMed1981

Modification of pituitary-adrenal feedback sensitivity in young rats by neonatal treatment with cortisol.

Neonatal exposure of rats to cortisol acetate was found to alter pituitary-adrenal feedback regulation at 20-25 days of age. Plasma levels of adrenocorticotrophin (ACTH) after ether stress were reduced in cortisol-treated rats pre-treated with 100 microgram corticosterone/100 g body weight, while rats given vehicle neonatally did not show suppression of the ACTH response below levels in animals given saline only or not injected as pre-treatments. Neonatal cortisol increased sensitivity to dexamethasone in inhibition of the stress response; cortisol-treated animals had a reduced plasma corticosterone response to stress 3 h after pre-treatment with 1.25, 2.5, 25, or 250 microgram dexamethasone/100 g body weight, while the stress response in animals given vehicle neonatally was not inhibited by the lowest dosage of dexamethasone. Neonatal cortisol treatment did not affect corticosteroid-binding globulin (CBG) binding capacity in plasma of 25-day-old animals. Thus, neonatal treatment with cortisol appears to increase feedback sensitivity to circulating corticosteroids at 20-25 days of age.

Adrenocorticotropic Hormone↗
PubMed1980

Serotonergic and catecholaminergic influence on thyroid function in the vervet monkey.

Vervet monkeys were pharmacologically treated acutely and with repeated dose loading to alter serotonergic systems to assess the role of serotonin in the regulation of the hypothalamus-pituitary-thyroid axis. Acute L-tryptophan administration failed to alter basal levels of thyroid hormones but did decrease the TRH-induced TSH response. Repeated dose loading of tryptophan or 5-hydroxytryptophan increased blood serotonin and plasma T3 and decreased plasma TSH. The tryptophan hydroxylase inhibitor p-chlorophenylalanine yielded decreased blood serotonin, but did not affect plasma TSH, T4 or T3. The monoamine oxidase inhibitor chlorgyline also resulted in increased blood serotonin, but increased plasma TSH and T4 and decreased T3. These data may be explained by a unitary hypothesis involving central catecholaminergic, rather than serotonergic, control of TRH release. Chlorgyline may produce its effects predominantly by facilitating catecholaminergic stimulation of TRH release resulting in increased TSH and a consequent increase in T4. It is suggested that the effects of tryptophan and 5-hydroxytryptophan result from increases in serotonin levels in the thyroid gland to produce an increase in T3 with a compensatory decrease in TSH via negative feedback. The differences observed between the acute and repeated dose loading studies stress the need for both types of studies before drawing conclusions about the effects of pharmacological manipulations on hormonal levels.

5-Hydroxytryptophan↗
PubMed1979

Hypothalamus-pituitary-thyroid axis interactions with pineal gland in the rat.

We examined in the rat several possible relationships between the pineal gland and the hypothalamus-pituitary-thyroid axis. The pineal gland, the retina, and the hypothalamus exhibited a diurnal rhythm in thyrotropin-releasing hormone (TRH) content with peak values occurring around 1200 h. This rhythm in the hypothalamus was abolished by constant light but was not affected by pinealectomy. Nor did pinealectomy affect hypothalamic TRH content, pituitary content of thyroid-stimulating hormone (TSH) or prolactin; serum levels of (TSH), triiodothyronine (T3), or thyroxine (T4), or serum free-thyroxine index; or free-triiodothyronine index. Melatonin did not affect TSH or prolactin release from the anterior pituitary or TRH release from the hypothalamus in vitro. Isoproterenol did not affect the TRH content of pineal glands in vitro; nor did TRH or T3 affect basal or stimulated activities of serotonin N-acetyltransferase, the presumed controlling enzyme in melatonin production. We found no evidence for significant interactions between the pineal gland and the hypothalamus-pituitary-thyroid axis.

Animals↗
PubMed1979

Effects of neonatal hydrocortisone treatment of pituitary and adrenocortical response to stress in young rats.

Administration of corticosteroids to rat pups within the first several days of life results in retardation of several behavioral, neurophysiological, and biochemical developmental patterns. At 25 days of age, animals treated neonatally with 1.0, 0.5, or 0.1 mg hydrocortisone acetate showed dose-dependent decreases in plasma ACTH following 2.5 min continuous exposure to ether. On day 20, plasma corticosterone values did not differ between these groups 15 min after ether stress, but lower values were seen 60 min after ether in animals treated at birth with 0.5 mg hydrocortisone. At 45--48 days of age, hydrocortisone-treated animals exposed to one of 2 different stressors showed decreased plasma corticosterone response to stress; females had lower corticosterone levels following both stressors, while males showed suppressed corticosterone levels following exposure to the mild (novelty) but not to the intense (ether) stress. These data demonstrate that neonatal exposure to hydrocortisone results in decreased CNS-pituitary responsivity to stress at 20--25 days of age, and that the adrenocortical response to stress in impaired at 45--48 days of age.

Adrenocorticotropic Hormone↗
PubMed1977

Hemodynamic effects of chlorpromazine in patients with acute myocardial infarction and pump failure.

The intravenous administration of chlorpromazine in 12 patients with acute myocardial infarction and altered pump function was followed by a significant reduction in systemic vascular resistance (28.4%) and an increased cardiac index (23.0%). The drug also produced a significant decline in mean pulmonary capillary wedge pressure (38.2%), while the heart rate and mean stroke work index did not change significantly. Although the mean blood pressure decreased by 18.3%, the transymocardial pressure gradient was not affected. A significant reduction in the major determinants of myocardial oxygen consumption, such as arterial blood pressure and left ventricular wall tension, suggested a decrease in myocardial demand for oxygen. Improvement of left ventricular performance was associated with a sedative effect in most of the patients. Intravenous administration of chlorpromazine proved to be of benefit in patients with moderate to severe congestive heart failure and cardiogenic shock.

Acute Disease↗
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↗