Determination of Seven Unconjugated Steroids in the Blood and Seminal Plasma of the Fertile Male Rabbit

Saksena, S.K.; Lau, I.F.; Chang, M. C.

doi:10.1159/000178788

Cited by 15 publications

(8 citation statements)

References 8 publications

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“…This would provide at a first estimate, with all the inherent assumptions including any level of endogenously derived tissue DHEA, the desired concentration to achieve the proper range of the presumed active concentration at tissue sites in the eye. We used a 3% DHEA concentration but the actual values measured in the anterior chamber fluid after 2 days of two drops per day were 3-to 30-fold less (0.02 Ìg/200 Ìl, table 4) than that calculated to be needed to be functionally active [1,2,33,34]. This discrepancy may well account for low functional pharmacologic activity seen in the present experiments.…”

Section: Discussionmentioning

confidence: 78%

“…The DHEA concentration required at the site of action is estimated, from the literature [1,2,33,34], at between 1 and 10 ÌM. With this information it is helpful to calculate the drug concentration required to be delivered to the eye.…”

Section: Discussionmentioning

confidence: 99%

“…While there is literature indicating that DHEA exists in the rabbit, it has not been examined as a function of age in this species [1,2,33,34]. Young rabbits may not behave similarly to primates in regard to DHEA reaction or pharmacological response [12,33].…”

Section: Discussionmentioning

confidence: 99%

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Influence of Dehydroepiandrosterone on Rabbit Intraocular Pressure

Kearse¹,

McIntyre²,

Johnson

et al. 2000

Ophthalmic Res

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Purpose: The systemic concentration of dehydroepiandrosterone decreases with age in primates while in humans intraocular pressure (IOP) increases with aging. This study was designed to investigate if a relationship existed between dehydroepiandrosterone and IOP in pigmented rabbits. Methods: Animals were treated unilaterally for 6 weeks with topical 3% dehydroepiandrosterone in 30% 2-hydroxypropyl-beta-cyclodextrin; the contralateral eye received vehicle alone. Drops were applied, and IOP measured, twice daily. Results: Small, but statistically significant, drug-related effects were found. IOP was consistently higher in the afternoon; the afternoon minus morning difference in IOP, however, decreased with time. Topical, radioactive drug application indicated very low level penetration into aqueous humor, iris, corneal epithelium, the rest of the cornea, or bulbar conjunctiva. Conclusion: The small drug-related effects may be due, in large part, to poor intraocular drug penetration. The circadian rhythm of IOP appears to be time-dependent in chronic studies with a gradual loss of IOP difference between a.m. and p.m. readings.

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Section: Discussionmentioning

confidence: 78%

Section: Discussionmentioning

confidence: 99%

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Influence of Dehydroepiandrosterone on Rabbit Intraocular Pressure

Kearse¹,

McIntyre²,

Johnson

et al. 2000

Ophthalmic Res

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“…Extraction was accomplished by mixing the plasma samples (0-7-1-0 ml) with 10 ml diethyl ether on a vortex mixer for 45 sec. Progesterone and oestradiol-17 ß were separated on microcelite columns (Saksena, Lau & Chang, 1977) and their concentrations analysed by radioimmunoassay (Saksena et al, 1976). All comparisons were based on samples measured in a single assay.…”

Section: Studymentioning

confidence: 99%

The pituitary-ovarian complex in the aged anoestrous golden hamster

Parkening¹,

Collins²,

Lau³

et al. 1982

Reproduction

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Plasma and pituitary hormones of young (3--5 months of age) dioestrous hamsters with normal cycles and aged (13--17 months of age) anoestrous hamsters were compared. The anoestrous hamsters exhibited lower plasma values of progesterone (P less than 0.001), oestradiol-17 beta (P less than 0.005) and prolactin (P less than 0.001) and higher levels of plasma gonadotrophins (P less than 0.001) than did the dioestrous animals. Pituitary concentrations of LH were higher (P less than 0.005) in anoestrous hamsters, but pituitary FSH and prolactin values did not differ. In another series of experiments three groups of hamsters (3--5- and 13--17-month-old with normal cycles and 13--17-month-old in anoestrus) were ovariectomized. Blood samples were taken by cardiac puncture every 3--4 weeks after receiving s.c. injections of oestradiol-17 beta (1 or 10 micrograms/100 g body wt) for 2 or 9 consecutive days. The markedly lower levels of gonadotrophins in aged anoestrous hamsters indicated that the hypothalamic-hypophysial complex was incapable of responding to the same degree as it did in young and aged cyclic animals. Prolactin values were similarly depressed in all 3 groups. Oestradiol-17 beta treatment caused reduced gonadotrophin and increasing prolactin concentrations in all 3 groups. These results indicate that the ovaries of the senescent anoestrous hamster produce less steroids and suggest that age-related changes in the hypothalamic-hypophysial complex are largely responsible for the cessation of regular oestrous cycles.

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“…The recoveries for T, 5a-DHT and A4A ranged from 60 to 74, 70 to 85, and 72 to 85%, respectively. The details regarding intra-and interassay coefficient variations have been reported (22). Water blanks were below the sensitivity and were not subtracted from the values reported.…”

Section: Analysis O F Androgensmentioning

confidence: 99%

Effects of hCG on Serum Levels of Testosterone, Dihydrotestosterone and Androstenedione in Male Mice

1978

Self Cite

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The concentrations of testosterone (T), 5α-dihydrotestosterone (5α-DHT) and Δ⁴-androstenedione (Δ⁴A) in the circulating blood were increased by a single subcutaneous injection of 10 IU of hCG in the mouse. The response of androgen synthesis to hCG stimulation was rapid and persisted over a period of 96 h. The increased supply of T to the peripheral organ(s) under the stimulation of hCG might contribute to an increase in circulating 5α-DHT. However, the changes in T/5α-DHT ratio implies that the stimulation of T and 5α-DHT production by hCG were not of the same degree.

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Determination of Seven Unconjugated Steroids in the Blood and Seminal Plasma of the Fertile Male Rabbit

Cited by 15 publications

References 8 publications

Influence of Dehydroepiandrosterone on Rabbit Intraocular Pressure

Influence of Dehydroepiandrosterone on Rabbit Intraocular Pressure

The pituitary-ovarian complex in the aged anoestrous golden hamster

Effects of hCG on Serum Levels of Testosterone, Dihydrotestosterone and Androstenedione in Male Mice

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