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Biomedical subjects

R T Rubin

Publications and source records attributed to R T Rubin.

At least 91 records · Page 5Linked to original sources
PubMed1983

Neonatal hypothyroidism: effect on the circadian variation of serum TSH in adult male rats.

Newborn rats were rendered hypothyroid during the first post-natal week and then studied as adults. At 80 days of age, groups of control and neonatally treated animals were sacrificed at the peak (13.00 h) and trough (07.00 h) of the serum thyroid stimulating hormone (TSH) circadian rhythm. Both control and treated animals showed the normal peak and trough fluctuation of serum TSH, although the animals made hypothyroid neonatally had serum TSH levels which were less than those of the control animals. Serum thyroxine (T4) levels of control and treated animals were similar at the trough of the serum TSH rhythm (07.00 h), but the (T4) levels of the neonatally hypothyroid animals were significantly lower than those found in the control animals at the peak of the TSH rhythm (13.00 h). The results of this experiment indicate that the central nervous system (CNS) regulation of the circadian pattern of serum TSH is maintained in adult animals made hypothyroid neonatally, and supports the results of previous studies which indicate an enhanced sensitivity of TSH secretion to feedback suppression by thyroid hormones.

Age Factors↗
PubMed1983

Oxytocin and prolactin responses in long-term breast-feeding.

Plasma levels of oxytocin and prolactin were measured before and during 12 minutes of breast pump stimulation in five healthy, lactating, amenorrheic women on three occasions: ten to 90 days post partum, 90 to 180 days post partum, and 180 days to one year post partum. Baseline mean (+/- SEM) plasma oxytocin levels were similar in the three study periods. Mean stimulated plasma oxytocin levels increased in the three study periods (each P less than .001; mean baseline versus stimulated). Stimulated plasma oxytocin values were significantly greater at ten to 90 than at 90 to 180 days (P less than .05; analysis of variance). Baseline serum prolactin levels were 61 +/- 9.5, 36 +/- 8.6, and 33 +/- 10.8 ng/ml, respectively (not significant; one-way analysis of variance). Mean stimulated prolactin levels were 71 +/- 8.1, 43 +/- 4.5, and 43 +/- 2.8 ng/ml, respectively (not significant). Thus, the oxytocin secretory reflex continues in long-term lactation for the first year post partum. In addition, breast stimulation in long-term lactating women continues to produce a slight increase in serum prolactin levels.

Adult↗
PubMed1982

Saliva cortisol levels following dexamethasone administration in endogenously depressed patients.

Saliva and serum cortisol levels were measured in 11 patients with primary major depression, endogenous subtype, and in 9 control subjects before and 8, 16, and 24 hours after dexamethasone administration (1.0 mg p.o.). Six of the 20 subjects had postdexamethasone serum cortisol concentrations greater than 50 ng/ml and thus were considered "escapers" from dexamethasone suppression. These six subjects also had saliva cortisol concentrations which were significantly elevated compared to those of the suppressors. Measurement of saliva cortisol holds promise as a non-invasive technique for assessing CNS-pituitary-adrenal function in endogenously depressed patients.

Depressive Disorder↗
PubMed1981

Postnatal gonadal steroid effects on human behavior.

Gonadal steroid hormones, active during fetal life, continue after the birth of a fetus to influence the central nervous system and affect behavior. The characteristically different circulating concentrations of male and female steroid hormones in men and women appear to be partial determinants of certain sexually dimorphic behaviors, interacting in a complex way with psychological and sociocultural factors as well as with other biological factors. This interaction is highlighted in research on testosterone and aggression in men, mood and the menstrual cycle in women, and pubertal sex role reversal in pseudohermaphrodites.

Affect↗
PubMed1981

Neonatal dexamethasone administration. I. Temporary delay of development of the circadian serum corticosterone rhythm in rats.

A series of experiments was undertaken to examine the effects of neonatal dexamethasone administration on the development of the circadian serum corticosterone rhythm in rats. Initial experiments showed that the rhythm began normally on postnatal day 18 in untreated animals. Then 1-day-old rats were injected sc with dexamethasone acetate (1, 10, or 100 microgram), dexamethasone phosphate (1, 3, or 5 microgram) beginning on day 1. Appropriate vehicle controls were included. At most doses and dosage regimens, rat pups were sacrificed at 0700 and 1900 h on postnatal days 16, 18, 20, and 22, but at the highest doses, they were sacrificed only on days 25 and 30. The single dexamethasone acetate injection (100 microgram) delayed the appearance of the corticosterone rhythm for 2 days compared to that in the vehicle-injected controls. Similarly, the 3 consecutive injections of dexamethasone phosphate (5 microgram) delayed the appearance of the rhythm for 4 days. All other dexamethasone dosage regimens were ineffective in altering the onset of the circadian corticosterone rhythm.

Animals↗
PubMed1981

Neonatal dexamethasone administration. II. Persistent alteration of circadian serum anterior pituitary hormone rhythms in rats.

Newborn male rats were treated SC with dexamethasone phosphate (100 microgram) or dexamethasone acetate (100 microgram) on postnatal day 1, dexamethasone phosphate (5.0 microgram) opn postnatal days 1, 2, 3, or the corresponding drug vehicle. All animals were sacrificed 65-70 days later at previously determined daily trough and peak times of serum LH, TSH, and corticosterone: 0700 and 0100 h for LH, 0700 and 1300 h for TSH, and 0700 and 1900 h for corticosterone. None of the three dexamethasone treatment regimens affected the circadian variation of serum LH or corticosterone. Dexamethasone phosphate (100 microgram) altered the normal circadian rhythm of serum TSH in the adult animals, but the other two dexamethasone treatments did not affect the TSH rhythm. Basal 0700 h serum levels of FSH, PRL, and GH were also measured in these animals; none of the dexamethasone treatments altered the levels of these hormones compared to levels in the vehicle-injected controls.

Animals↗
PubMed1980

beta-Endorphin and schizophrenia.

To study the effects of beta-endorphin in chronic schizophrenia, nine male patients participated in a double-blind crossover comparison of a single intravenous 20-mg injection of beta-endorphin and saline. Bolus injection of beta-endorphin from an albumin-coated syringe produced markedly higher plasma concentrations than did slow intravenous infusion from a non-albumin-coated syringe. Beta-endorphin intravenously injected in nine patients produced a statistically significant increase in serum prolactin levels. In one patient, both 10 mg of morphine sulfate and 20 mg of beta-endorphin produced similar increases in the alpha power of the EEG. In eight patients, beta-endorphin administration was associated with a statistically significant but not clinically obvious improvement in schizophrenic symptoms.

Adult↗
PubMed1980

Serum haloperidol determinations in psychiatric patients. Comparison of methods and correlation with serum prolactin level.

Twenty-one serum samples from 11 schizophrenic patients receiving long-term haloperidol therapy were analyzed for haloperidol concentrations by two different radioimmunoassays (RIAs) and gas chromatography (GC). There was a good correspondence between the RIA and GC values over a wide range of drug concentrations. However, compared with the specific GC technique, both RIA methods overestimated haloperidol concentrations, reflecting differences in the specificities of the two RIA antibodies. One of the RIA methods had the requisite specificity for application to patients treated with long-term haloperidol therapy, although further methodological refinement will be required for its general clinical application. Haloperidol values determined by GC and RIA analyses correlated highly with prolactin concentrations in the same samples, suggesting that the usefulness of prolactin measurement as an "in vivo bioassay" for circulating levels of haloperidol should be further explored.

Chromatography, Gas↗
PubMed1980

Anxiety induced by flooding therapy for phobias does not elicit prolactin secretory response.

Eight subjects with severe phobias to insects and small animals had blood samples taken for measurement of prolactin concentration at regular intervals during five sessions of 3 hr duration each. Severe anxiety was induced by treating the phobia with in vivo flooding during the middle hour of the third and fourth sessions. Despite intense anxiety experienced by the subjects, they showed no change in plasma prolactin levels.

Anxiety↗