Plasma vitellogenin and 17β-estradiol levels during the annual reproductive cycle of Podarcis s. sicula Raf

Carnevali, Oliana; Mosconi, Gilberto; Angelini, F.; Limatola, Ermelinda; Ciarcia, Gaetano; Polzonetti-Magni, A.M.

doi:10.1016/0016-6480(91)90079-l

Cited by 51 publications

(29 citation statements)

References 19 publications

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“…The ovarian cycle of this squamate shows a well-defined seasonal rhythm characterized by the winter, vitellogenic, and postreproductive periods; cyclical ovarian changes, previously described [14][15][16], are consistent with a quiescent ovary during winter and vitellogenic and steroidogenetic activity during the reproductive period (April-June) followed by a summer refractoriness.…”

Section: Introductionmentioning

confidence: 52%

Presence and Steroidogenetic Activity of β-Endorphin in the Ovary of the Lizard, Podarcis S. Sicula Raf1

Polzonetti-Magni

Facchinetti

Carnevali

et al. 1994

Biology of Reproduction

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In mammals, proopiomelanocortin (POMC)-related peptides are involved in reproductive processes at both the hypothalamopituitary and ovarian levels. Through immunocytochemical and physiological in vitro studies, evidence for a diffuse POMC-related opioid system in the lizard Podarcis s sicula is provided. In the lizard ovary, ,-endorphin (-EP)-like immunoreactive cells were observed within the granulosa layer; the immunoresponse showed seasonal variation, being most pronounced in the winter ovary. HPLC followed by immunoassay showed that acetyl P-EP is the main form of POMC-related peptide in both pituitary and ovary. In vitro studies showed that picomolar amounts of P-EP stimulate follicular estrogen production during both the reproductive and winter phases; induction was found to be higher in the reproductive phase.The data reported here provide evidence for the physiological role played by -EP in the reproductive function of Podarcis s sicula via induction of ovarian production of estradiol-17, which is the main factor responsible for the vitellogenic process.

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Section: Introductionmentioning

confidence: 52%

Presence and Steroidogenetic Activity of β-Endorphin in the Ovary of the Lizard, Podarcis S. Sicula Raf1

Polzonetti-Magni

Facchinetti

Carnevali

et al. 1994

Biology of Reproduction

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“…Previous studies on the same species have demonstrated that a similar body condition determines reproductive status (vitellogenic versus nonvitellogenic females) and the occurrence of mating , and that plasma estradiol levels control the induction of vitellogenesis . Indeed, estradiol is the primary stimulus for vitellogenesis in many vertebrates (Ho et al, 1982;Callard, Riley, and Perez, 1990;Peyon, Baloche, and Burzawa-Gerard, 1993;Carnavelli, Mosconi, Angelini, Limatola, Ciarcia, and Polzonetti-Magni, 1991) and strongly influences sexual behavior in reptiles (Halpern, Morrell, and Pfaff, 1982;Mason, 1992; but see Whittier, Mason, and Crews, 1987;Saint Girons et al, 1993). Taken together, these data show that reproductive status and sexual behavior are tightly linked in female asp vipers.…”

Section: Discussionmentioning

confidence: 99%

Fat Is Sexy for Females but Not Males: The Influence of Body Reserves on Reproduction in Snakes (Vipera aspis)

Aubret

Bonnet

Shine

et al. 2002

Hormones and Behavior

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Reproduction is energetically expensive for both sexes, but the magnitude of expenditure and its relationship to reproductive success differ fundamentally between males and females. Males allocate relatively little to gamete production and, thus, can reproduce successfully with only minor energy investment. In contrast, females of many species experience high fecundity-independent costs of reproduction (such as migration to nesting sites), so they need to amass substantial energy reserves before initiating reproductive activity. Thus, we expect that the relationship between energy reserves and the intensity of reproductive behavior involves a threshold effect in females, but a gradual (or no) effect in males. We tested this prediction using captive vipers (Vipera aspis), dividing both males and females into groups of high versus low body condition. Snakes from each group were placed together and observed for reproductive behavior; sex-steroid levels were also measured. As predicted, females in below-average body condition had very low estradiol levels and did not show sexual receptivity, whereas males of all body condition indices had significant testosterone levels and displayed active courtship. Testosterone levels and courtship intensity increased gradually (i.e., no step function) with body condition in males, but high estradiol levels and sexual receptivity were seen only in females with body reserves above a critical threshold. The energetics of reproduction has been a central theme in the ecological study of life history variation (Hirshfield and Tinkle, 1975;Morris, 1987Morris, , 1992Winkler and Wallin, 1987;Stearns, 1992; Monaghan and Nager, 1997), and more recently this topic has become an important focus in behavioral endocrinology (Cherel, Mauget, Lacroix, and Gilles, 1994;Bronson, 1998). It is obvious that organisms cannot reproduce in the total absence of energy reserves (Frish, 1978;Frish and McArthur, 1974), but the relationship between the amount of energy reserves and reproductive output (or effort) is complex and varies among species. In some species there is a linear relationship between energy reserves and reproductive output. In others there appears to be no discernible relationship (e.g., if clutch and offspring sizes are fixed) or a complex nonlinear relationship between the two variables. For example, many organisms are "capital breeders" that rely on previously gathered energy stored in the form of body reserves (i.e., fat bodies, proteins) rather than on current energy intake to fuel the energetically costly process of reproduction (Drent and Daan, 1980;Jö nsson, 1997; Bonnet, Bradshaw, and Shine, 1998). In such species, life history theory predicts that a threshold level of energy reserves is necessary for a reproductive cycle to begin, rather than a linear relationship in which an increment in energy availability adds an increment in reproductive output (Schaffer, 1974;Bull and Shine, 1979;Stearns, 1992). Several empirical studies provide evidence for nonlinear relationships between...

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“…alligators [Alligator mississippiensis; Guillette et al, 1997;Bermudez et al, 2005], these studies have been conducted primarily in free-ranging animals. Studies on hormonal systems have been conducted on a few lizard species including male and female sex steroids in the lacertid lizard [Podarcis sicula ;Carnevali et al, 1991;Ando et al, 1992], the blue spiny lizard [Callard et al, 1972], and the mountain spiny lizard [Sceloporus jarrovi; Woodley and Moore, 1999]. Androgens were studied in the green anole [Anolis carolinesis; Wade, 1997] and the male eastern fence lizard [S. undulatus;McKinney and Marion, 1985].…”

Section: Introductionmentioning

confidence: 99%

Reproductive and thyroid hormone profiles in captive Western fence lizards (Sceloporus occidentalis) after a period of brumation

2007

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Seasonal fluctuation in serum concentrations of sex steroid (testosterone [T] and 17beta-estradiol [E(2)]) and thyroid (triiodothyronine [T(3)] and thyroxine [T(4)]) 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 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 Biol 27:36-48, 2008. (c) 2007 Wiley-Liss, Inc.

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Plasma vitellogenin and 17β-estradiol levels during the annual reproductive cycle of Podarcis s. sicula Raf

Cited by 51 publications

References 19 publications

Presence and Steroidogenetic Activity of β-Endorphin in the Ovary of the Lizard, Podarcis S. Sicula Raf1

Presence and Steroidogenetic Activity of β-Endorphin in the Ovary of the Lizard, Podarcis S. Sicula Raf1

Fat Is Sexy for Females but Not Males: The Influence of Body Reserves on Reproduction in Snakes (Vipera aspis)

Reproductive and thyroid hormone profiles in captive Western fence lizards (Sceloporus occidentalis) after a period of brumation

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