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Biomedical subjects

B Withyachumnarnkul

Publications and source records attributed to B Withyachumnarnkul.

24 records · Page 2Linked to original sources
PubMed1987

Dynamic uptake of radioactive substance in rat salivary gland following 3H-melatonin administration.

Dynamics of radioactive accumulation in rat greater salivary gland following systemic administration of 3H-melatonin was studied to determine a possible action of the hormone in the gland. Progressive decline of 3H-melatonin concentrations was found in the serum, lung, skeletal muscle, liver, kidney, and salivary gland during 60 min following the administration. On the contrary, there was a progressive accumulation of radioactive substance other than 3H-melatonin in the salivary gland but not in other tissues mentioned. The radioactivity was also progressively and preferentially localized in the nuclear fraction of the gland cells. These results suggest a possible direct action of melatonin derivative in rat salivary gland.

Animals↗
PubMed1986

Retention of radioactive substances in the hypothalamus, anterior pituitary, and reproductive organs of male rats after 3H-melatonin administration.

Radioactive concentrations were determined in serum, lung, hypothalamus, anterior pituitary, testis, and accessory sex organs of adult male rats at 2, 20, 30 and 60 min after intravenous 3H-melatonin administrations. The retention patterns of 3H-melatonin and other radioactive substance (3H-non-melatonin) in these tissues were compared. The anterior pituitary demonstrated best tissue retention with highest concentration of 3H-melatonin. The testis and prostate gland accumulated 3H-non-melatonin in an increasing manner from 2 to 60 min. The radioactive substances were also preferentially and progressively located in the nuclear fraction of the anterior pituitary, hypothalamus, testis, and prostate gland. This study leads to the following suggestions: the anterior pituitary is another target organ of melatonin; melatonin is converted into other active material which exerts its action in the testis and prostate gland; melatonin and its active derivative exert their action through the nuclei of their respective cells.

Animals↗
PubMed1982

Plasma testosterone levels and sexual performance of young obese male Zucker rats.

The sexual behavior of obese male Zucker rats was studied at the age of 7, 8, 9, 10, 11, 14, and 16 weeks. Between 12-14 weeks of age, obese rats were treated with 400 micrograms testosterone propionate daily. Plasma testosterone levels were determined at the age of 10, 14, 16, and 20 weeks. Compared to lean rats, the sexual performance of the obese rats was abnormal at all ages. Plasma testosterone levels of obese rats were significantly lower at the age of 20 weeks but not at the age of 10 and 16 weeks, compared to those of their lean littermates. At the age of 14 weeks, after 2 weeks of testosterone treatment, plasma testosterone concentration rose to levels significantly higher than those of their lean littermates. However, there was no improvement in their sexual behavior following this period of hormone treatment. This study strongly suggests that obese male Zucker rats have abnormal reproductive function at all ages and that testosterone deficiency is not a primary cause of this abnormality.

Age Factors↗
PubMed1980

Sexual behavior of the obese male Zucker rat.

Obese male Zucker rats displayed inadequate sexual behavior at four months placed with ovariectomized lean females pretreated with estrogen and progesterone. Only one out of seven obese males ejaculated during the test sessions. Diet-restricting the obese males at five months of age did not improve their sexual behavior when tested at six months of age. At ten months of age none of the obese males ejaculated during the test sessions. Lean littermates ejaculated during the sessions at all ages tested. Obese males which do ejaculate are capable of inducing pseudopregnancy in intact lean females. These findings suggest that inadequate sexual behavior is one factor contributing to the reduced reproductive capacity of obese male Zucker rats.

Animals↗
PubMed1980

Melatonin concentration in cerebrospinal fluid, peripheral plasma and plasma of the confluens sinuum of the rat.

A procedure is described for collection of blood from the confluens sinuum of the rat. Melatonin concentration, measured by RIA, in plasma of the confluens was found to be significantly higher than that in peripheral plasma. Melatonin levels in cerebrospinal fluid of the cisterna magna were always lower than those in plasma and exhibited no significant changes which paralleled those occurring in plasma with darkness. It is concluded that, in the rat, the major route of secretion of melatonin by the pineal gland is into the blood of the confluens sinuum.

Anesthesia↗