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Biomedical subjects

R Ulrich

Publications and source records attributed to R Ulrich.

At least 163 records · Page 9Linked to original sources
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

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↗
PubMed1971

Delayed timeout as a procedure for reducing disruptive classroom behavior: a case study.

The disruptive behavior of a 9-yr-old boy was eliminated by the illumination of a light on the subject's desk, which represented the loss of free time later in the day. Instructions alone failed to reduce the frequency of disruptive behavior. When the light was removed and disruptive behavior no longer resulted in a loss of free time, disruptive behavior returned to its previous level.

Journal Article↗
PubMed1970

Harderian gland: influence on pineal hydroxyindole-O-methyltransferase activity in neonatal rats.

A circadian rhythm has been found in hydroxyindole-O-methyltransferase activity of the pineal gland of blinded 12-day-old rats. Five additional hours of lighting can partly prevent the nocturnal increase in pineal hydroxyindole-O-methyltransferase activity in such rats. Removal of the Harderian gland abolishes this response to light in 12-day-old blinded animals, giving further support to the suggestion that this gland may function as an extraretinal photosensitive organ influencing the pineal gland in blinded suckling rats.

Animals↗
PubMed1969

Punishment of shock-induced aggression.

Squirrel monkeys were restrained in a chair equipped with a tail-shock apparatus and a pneumatic bite hose located in front of the subject's face. An aggressive response was recorded when the monkey bit the hose. Initial sessions in which no shocks were delivered produced some biting. When biting during these sessions stabilized at a near-zero level, regularly scheduled shocks were delivered to the monkey's tail, causing a consistently higher rate of biting. After several sessions under these conditions, a punishment phase was introduced in which the previous shock conditions were maintained, and every bite was followed immediately by another, more intense shock. Biting under these conditions was suppressed to a near-zero level. When the punishment contingency was removed, biting increased. With one subject, two additional bite-contingent stimuli were examined: (1) a milder shock that, when made contingent upon hose biting, also suppressed that response, and (2) a contingent tone that had no obvious suppressing or facilitating effect. Individual differences among subjects were extreme, but the effect of bite-contingent shock was consistent. Observations of the subjects during the punishment sessions indicated the existence of certain side effects that resulted from the use of punishment to suppress shock-induced aggression.

Aggression↗
PubMed1967

Circadian rhythms of liver enzymes and their relationship to enzyme induction.

Tyrosine alpha ketoglutarate transaminase, which is rapidly induced by various agents, shows circadian rhythmicity in the intact rat. This rhythmicity is only slightly altered after adrenalectomy, indicating that adrenal hormones do not play a major role in the metabolic control of the activity of tyrosine alpha ketoglutarate transaminase. On the other hand, phenylalaninepyruvate transaminase, which is not inducible over the same time period, does not show circadian variation. The results suggest that the sensitivity of an enzyme's regulating system to inducing agents may be related to the inherent circadian rhythm of the enzyme.

Adrenalectomy↗
PubMed1967

Interaction between reflexive fighting and cooperative escape.

Subjects separated by a Plexiglas partition were trained to follow a cooperative escape procedure which produced behavior like the escape responding of individual subjects. Removal of the partition produced fighting and less efficient escape. Efficient escape behavior was restored and fighting disappeared when the partition was replaced. Neither increased space nor a moving toy affected escape behavior. The results indicate that switching animals from an isolated to a social situation produced a change in the effect of shock upon escape which was related to shock-induced fighting.

Animals↗