Effect of castration and of male hormone administration on the tissue respiration and thyroid activity of the checkered water snake (original) (raw)
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Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2004
The renal sexual segment (RSS) of immature Northern and Diamondback Water Snakes and Red-Sided Garter Snakes exhibited varying responses to testosterone or 17h-estradiol. In both male and female water snakes, kidney mass was not a reliable indicator of hormone treatment, whereas tubule diameter, epithelial height and number of sexual granules responded to hormone treatment. In male water snakes, either hormone initiated granule development by day 16; by day 23, only testosterone increased granule density. Female water snakes receiving either hormone exhibited a small number of granules by day 16; by day 23, granules increased only in Diamondback Water Snakes receiving testosterone. Hormones did not initiate RSS hypertrophy in female Red-Sided Garter Snakes. Tubule diameter and epithelial height of testosterone-treated males exhibited significant hypertrophy, while 17h-estradiol initiated significant increases in tubule diameter. Garter snakes initiated sexual granule development in response to hormone treatment with males exhibiting a greater response than females and testosterone stimulating a greater response than 17h-estradiol. Sex steroids appear to mimic sexual maturity in immature snakes initiating RSS development. Whereas the RSS of adult males respond to testosterone, our data suggest specific changes in the RSS of females during maturation effectively negates the effect of 17h-estradiol evident in immature female RSS. D
Hormones and Reproductive Cycles in Snakes
Hormones and Reproduction of Vertebrates, 2011
The The study study of of the the hormonal hormonal regulation regulation of of reproduction reproduction in in snakes snakes is is in in its its infancy. infancy. Studies Studies have have disproportionately disproportionately examined examined temperate temperate zone zone viperid viperid and and colubrid colubrid snakes, snakes, especially especially the the red red sided sided garter garter snake snake (Thamnophis (Thamnophis sirtalis sirtalis parietalis). parietalis). Indeed, Indeed, extensive extensive observational observational and and experimental experimental studies studies on on T. T. s. s. parie parie talis talis form form the the basis basis for for our our understanding understanding of of the the hormonal hormonal regu regu lation lation of of reproduction reproduction in in snakes. snakes. This This review review focuses focuses on on seasonal seasonal hormone hormone concentrations concentrations in in snakes snakes in in relation relation to to events events in in the the reproductive reproductive cycle; cycle; the the limited limited data data available available on on hypothalamic hypothalamic hormones, hormones, gonadotropins gonadotropins (GTHs),
Journal of Experimental Zoology, 1994
Administration of different doses of estrogen (5, 10, and 25 pg) in Anabas testudineus and Calotes versicolor inhibited the activities of alanine aminotransferase and aspartate aminotransferase. In Calotes, higher doses of estrogen (10 and 25 pg) increased the activity of glutamate dehydrogenase and in Ariabas it was stimulated by all three doses. The total protein and RNA were also increased by all three doses of hormone in Anabas and Calotes. Higher doses of estrogen stimulated total DNA in Anabas and Calotes and the lowest dose (5 pg) did not have any significant effect. Activities of transaminases and glutamate dehydrogenase were inhibited and the protein content decreased by the administration of actinomycin and puromycin or simultaneous administration of estrogen and protein synthesis inhibitors. Actinomycin and puromycin alone did not have any significant effect on total DNA in Anabas and Calotes. Actinomycin reduced the level of RNA and puromycin did not produce any significant effect in Calotes. In Anabas actinomycin as well as puromycin decreased total RNA content. Simultaneous administration of estrogen and these inhibitors prevented the hormone mediated increase in the level of RNA and DNA both in Anabas and Calotes.
Zoo Biology, 2008
hormones was determined in captive Western fence lizards (Sceloporus occidentalis). Samples were collected from male and female breeding pairs weekly for a 4-month period after their emergence from artificial brumation. Circulating levels of E 2 corresponded with the expected vitellogenic and ovulatory cycles in females, and surprisingly, E 2 in males followed a similar pattern, indicating a possible role in breeding behavior. Serum T was elevated in male lizards for the first 6 weeks after emergence from brumation, possibly related to an increase in the onset of active spermatogenesis. Thyroid hormones showed little cyclical activity throughout the breeding period, with the exception of small increases of T 3 at weeks 8 and 16, possibly implying an active role of this hormone with r r 2007 Wiley-Liss, Inc. ovulation in females. Overall, these baseline hormone data are not only useful in developing this animal as a laboratory reptile model for assessment of endocrine-mediated toxicity, but also of value for understanding herpetological endocrinology and for application in the conservation of threatened species. Zoo
General and Comparative Endocrinology, 1985
Circulating thyroxine (T,) and triiodothyronine (T,) were estimated by RIA in plasma samples of Calotes versicolor collected over a period of 28 months. Monthly observations on seasonal events, viz., molting, whole body O2 consumption, abdominal fat deposition, and testes weight were also made. Plasma T, ranged from 0.16 to 4.63 ngiml and T, from 0 to 1.76 rig/ml during the course of the year. Peaks of T, and T, coul d be related with prehibernating (October/November) and posthibernating (March/April) periods, when scale shedding and O2 consumption were also enhanced. Maximum abdominal fat deposition was found in prehibernatory months (October/November). Thyroid hormone levels declined sharply with entry into hibernation. Abdominal fat deposits gradually decreased, being almost depleted by the end of hibernation. The gradual increase in thyroid hormone concentration in the later half of hibernation may be associated with increased lipolysis and preparation of the oncoming reproductive period. Although T, and T, profiles were apparently parallel, discrepancies were observed. Posthibernatory peak of T, was maintained much longer than that of T, which declined earlier. Also the rise in the prehibernatory T, concentration was delayed as compared to that in T,.
Comparative Haematology International, 1996
This study deals with a general description of haematology and plasma chemistry of free-living males of the lacertid lizards Psamrnodromus algirus subjected to an experiment of testosterone supplementation. In control lizards the number of red blood cells -1700 000 cells/#l -was smaller than those published for birds and mammals. Haematocrit and haemoglobin content were 33% and 8.4 g/dl. However, they were greater than those reported for other lizards. Testosterone treatment reduced the number of red blood cells and haemoglobin content but did not affect red cell indexes. White blood cell number was 27000 cells//tl, a value higher than those previously published for other lizards. Lymphocytes, heterophils and azurophils counts were 22300, 3700 and 2000 cells//~l. Monocytes, eosinophils and basophils showed proportions lower than 500 cell//d. Testosterone treatment reduced the total number of leucocytes (17 000 cells//~l) and the number of lymphocytes (10 000 cell/#l). Glucose plasma level was in the range published for birds -250 mg/dl -in both control and treated lizards. Plasma proteins (3.6 g/dl), uric acid and urea (4.5 and 5.4 mg/dl, respectively) were similar to previously published values in lizards. Testosterone treatment increased only protein levels (8.2 g/dl).
Reproduction, 1990
Progesterone, 17-hydroxyprogesterone, androstenedione, 5\g=a\-dihydrotestosterone, dehydroepiandrosterone, testosterone and oestradiol concentrations in the plasma were measured by simultaneous radioimmunoassay in males of the lizard Podarcis s. sicula. Hormonal determinations were performed at monthly intervals from January to December (except for August). Testosterone and androstenedione reached peak values of 174\m=.\8 ng/ml and 21\m=.\4 ng/ml in the mating season (spring) and then testosterone fell abruptly to 5\m=.\9 ng/ml in June remaining at this level during hibernation when dehydroepiandrosterone (DHA) reached a maximal level of 28\m=.\5\m=+-\9\m=.\3 ng/ml. Castration resulted in a marked decrease of testosterone, androstenedione, dihydrotestosterone and DHA values, with DHA being significantly lowered only during the winter season. In castrated animals, however, testosterone and androstenedione persisted conspicuously in the plasma during the breeding period, suggesting that adrenal sex steroid output may change during the annual reproductive cycle. In intact animals, progesterone and oestradiol exhibited peak values during the refractory period after the mating season. We suggest a probable role of oestradiol in the induction of the refractory period in this lizard.
General and Comparative Endocrinology, 1982
The vena abdominalis of pentobarbital anesthetized frogs (Rana ridibundo) was cannulated for injection and blood sampling. After acetone and petroleum ether extraction, serum was concentrated 4 and 20 times and T, and T, were determined by radioimmunoassay. In 8 frogs, an injection of 10 pg synthetic TRH (pGlu-His-ProNHJ increased control levels of 0.35 f 0.08 ng Tdml after 1,2,4, and 8 hr, with a maximal increase up to 2.65 + 0.48 &ml after 4 hr. In 7 frogs, 1 pg TRH raised control levels of 0.52 + 0.22 &ml after 1,2, and 4 hr, with a peak value of 1.74 + 0.45 rig/ml after 2 hr. Control injections (Ringer), 0.01 and 0.1 pg TRH were without effect. Control levels of T, (0.029 + 0.005 &ml) were also raised after 4 hr (0.051 f 0.007 @ml) in 7 animals, but only with the lO+g TRH dose. Two days after removal of the pars distalis, circulating levels of T4 (but not T3) in frog serum were significantly depressed, whereas T3 and T4 content of thyroids remained unchanged. An intravenous injection of 10 pg TRH did not alter circulating levels of T, and T,. These results indicate that the activity of the thyroid gland of R. ridibunda is stimulated by intravenous injections of TRH and that this effect is mediated through the hypophysis.