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Biomedical subjects

W D Pfeifer

Publications and source records attributed to W D Pfeifer.

11 recordsLinked to original sources
PubMed1977

Effect of lysine vasopressin on pentylenetetrazol-induced retrograde amnesia in rats.

Lysine vasopressin (1 microgram/rat SC) administered 1 hr prior to either the acquisition trial or 24 hr retention trial facilitated passive avoidance retention. Amnesia was produced when a single 50 mg/kg (IP) injection of pentylenetetrazol was given immediately following the passive avoidance acquisition trial. A single injection of lysine vasopressin (1 microgram/rat SC) administered 1 hr prior to either the acquisition trial or 24 hr retention trial antagonized the amnesia.

Amnesia↗
PubMed1977

Liver enzyme adaptation after lithium administration in handled and nonhandled rats.

We have examined the interaction of lithium administration and the infant stimulation procedure of handling on hormonally regulated enzymes of liver. Animals handled in infancy show an increased morning corticosterone level in response to lithium feeding and markedly elevated serum glucose during refeeding following a two day fast, when compared to non-handled control animals. Lithium alters serum corticosterone both in response to the stress of fasting, and during the diurnal cycle following glucose refeeding. The handled and non-handled animals respond differently. These results are consistent with previously reported alterations in feedback regulation of ACTH secretion in handled animals. They also indicate a further modification of this system in response to lithium administration.

Animals↗
PubMed1976

Effects of lithium on inducible enzymes of rat liver.

Chronic lithium administration to female rats results in elevation of serum corticoids, lowering of serum glucose and altered induction of liver enzymes. The cortisol induction of tyrosine transaminase is increased selectively over that of tryptophan oxygenase. The glucose induction of glucokinase following a fast is increased by chronic lithium treatment but diminished by acute treatment. These results indicate that lithium may alter the glucose metabolic set-point in rats.

Adrenal Cortex Hormones↗
PubMed1976

Modification of the adrenal stress response by age and prior experience.

The adrenal stress response was examined in young and mature rats of both sexes by measuring the increase in adrenal tyrosine hydroxylase activity and serum corticosterone following exposure to electric footshock. Exposure to electric footshock for six minutes on three consecutive days elevated tyrosine hydroxylase activity in young and mature female rats and in young male rats, but failed to elevate enzyme activity in mature male animals. This decreased responsiveness of tyrosine hydroxylase in mature male rats could be overcome by giving prior experience with electric footshock. Age, sex, and prior experience interacted a affecting the levels of serum corticosterone in response to a three minute exposure to electric footshock. However, the most dramatic effect was due to prior experience, which reduced themagnitude and altered the time of the peak serum corticosterone response. These data demonstrated that the pituitary-adrenal system can be modified in old animals in a manner similar to the modification seen following infant stimulation, and indicate that several mechanisms may be invilved in the maturation and aging of a species.

Adaptation, Physiological↗
PubMed1976

Lithium accumulation in some endocrine tissues.

Lithium levels were measured in several tissues of rats after oral lithium administration for various periods of time. The lithium levels in the brain approached those of the serum while there was a marked accumulation of lithium in the pituitary and thyroid glands. When lithium was stopped there was no noticeable lag in clearance for any of the tissues examined, with the pituitary maintaining a significant elevation of lithium over the serum levels. Animals receiving lithium had higher levels of adrenal corticosterone under quiescent conditions and higher levels of plasma corticosterone thirty minutes after a brief electric footshock.

Adrenal Cortex↗