Abstract:
:This study investigates the effects of exogenous thyroxine (T4) on running endurance, tissue masses, and the activities of citrate synthase (CS), pyruvate kinase (PK), cytosolic alpha-glycerophosphate dehydrogenase (alpha-GPDH), and beta-hydroxyacyl Coenzyme A dehydrogenase (HOAD) in Sceloporus undulatus (eastern fence lizard). The enzymes were assayed to indicate maximal catabolic activities that support exercise. Parallel experiments were done on captive and field-active groups to determine whether responses in captive studies adequately predict responses in nature. Exogenous T4 was administered via intraperitoneal pellets. The effect of T4 on running endurance was dependent on the location of the experiment (P = 0.040) such that stamina was increased by T4 only in field-active lizards. At lower levels of biological organization, interactivity between T4 and experimental location was evident but less prevalent than at the level of the whole animal, and some location effects occurred independent of T4 treatment. Heart and kidney masses were significantly greater and total hind leg muscle mass was less in captive than in field-active lizards. Thyroxine reduced liver mass in both locations and kidney mass only in captive lizards. Mass-specific CS and alpha-GPDH in gastrocnemius muscle (mixed fiber type) and HOAD in heart were lower in captive than in field-active lizards; PK in heart and liver and alpha-GPDH in heart were higher in captive lizards. Thyroxine increased CS in liver and HOAD in heart, decreased alpha-GPDH in liver in both locations, and decreased alpha-GPDH in gastrocnemius only in captive lizards. The effects of T4 differed significantly between experimental locations in gastrocnemius muscle (T4 decreased PK only in captive lizards) and in liver (T4 increased PK in field-active lizards and decreased PK in captive lizards). The mechanistic basis of differences in stamina between captive and field-active and between placebo and T4-treated lizards is largely unexplained by the factors measured here, thus illustrating the uncertainty of predicting organismal performance from lower level measurements. Nonetheless, T4 has now been shown to have greater physiological activity in field-active than in captive Sceloporus with regard to resting and total daily metabolic rates and running endurance. The results of this study further confirm that endocrine experiments on captive animals may not predict responses in nature. Further efforts to clarify the physiological significance of seasonal variations in levels of thyroid hormones will have to involve, at least in part, invasive studies on field-active lizards.
journal_name
Gen Comp Endocrinoljournal_title
General and comparative endocrinologyauthors
John-Alder HB,Joos Bdoi
10.1016/0016-6480(91)90132-psubject
Has Abstractpub_date
1991-01-01 00:00:00pages
120-32issue
1eissn
0016-6480issn
1095-6840pii
0016-6480(91)90132-Pjournal_volume
81pub_type
杂志文章abstract::Only recently have the cardiac actions of parathyroid hormone and its N-terminal (1-34) fragment (bPTH(1-34] been examined. Parathyroid hormone was found to exert a positive chronotropic effect on the heart tissue of several mammals and one amphibian in vivo and/or in vitro. The purpose of the present study was to exa...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/0016-6480(84)90037-6
更新日期:1984-11-01 00:00:00
abstract::We examined the mechanism of amiloride-sensitive Na(+) channels (ENaC) activated by fANP in epithelial cells of frog urinary bladder by using a cell-attached patch-clamp technique. ENaC activities in the epithelial cells were significantly increased following administration of both 10(-9)M fANP and 10(-5)M 8-Br-cGMP. ...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/j.ygcen.2006.11.003
更新日期:2007-06-01 00:00:00
abstract::We have examined the distribution and physiological effects of three evolutionarily and sequence-related neuropeptides in Rhodnius prolixus. These neuropeptides, adipokinetic hormone (RhoprAKH), corazonin (CRZ) and adipokinetic hormone/corazonin-related peptide (RhoprACP) are present in distinct, non-overlapping neuro...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/j.ygcen.2013.10.012
更新日期:2014-01-01 00:00:00
abstract::The aim of this study was to identify the major C21 steroids produced in vivo during artificially induced final oocyte maturation and spawning in female common dentex (Dentex dentex). During the spawning season, mature females were treated with a gonadotropin-releasing hormone agonist (GnRHa)-loaded delivery system, w...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1006/gcen.2000.7519
更新日期:2001-07-01 00:00:00
abstract::In flatfishes with asynchronous and semicystic spermatogenesis, such as the Senegalese sole (Solea senegalensis), the specific roles of the pituitary gonadotropins during germ cell development, particularly of the follicle-stimulating hormone (Fsh), are still largely unknown in part due to the lack of homologous immun...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/j.ygcen.2014.10.009
更新日期:2015-09-15 00:00:00
abstract::Experiments were carried out to test the efficiency of cryopreservation of whole testicular tissue in tench Tinca tinca and goldfish Carassius auratus and compare it to cryopreservation of isolated testicular cells. Additionally, effects of three cryoprotectants (dimethyl sulphoxyde - Me2SO, methanol - MeOH and ethyle...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/j.ygcen.2016.07.005
更新日期:2017-05-01 00:00:00
abstract::Pancreatic polypeptide (PP) has been isolated from pancreatic extracts of the herring gull (Larus argentatus) using a radioimmunoassay employing an antiserum (PP 221), generated to the conserved C-terminal hexapeptide amide of mammalian PP. Gel permeation and reverse-phase HPLC fractionation of crude pancreatic extrac...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1006/gcen.1994.1029
更新日期:1994-02-01 00:00:00
abstract::Corticosterone, at baseline and moderately elevated levels, is thought to regulate energy mobilization during the predictable life-history cycle. In birds, corticosterone is known to be moderately elevated during migration, and some experiments on captive, but migratory active birds have shown that exogenous corticost...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/j.ygcen.2013.02.042
更新日期:2013-06-01 00:00:00
abstract::The aim of the study was to verify the effect of various hormonal agents [human chorionic gonadotropin (hCG) and salmon gonadoliberine analogue (sGnRHa)] applied at different stages of maturity of the females [out-of-season (maturation stage I) and in-season spawning (maturation stages II and IV)] on the proximate com...
journal_title:General and comparative endocrinology
pub_type: 临床试验,杂志文章
doi:10.1016/j.ygcen.2016.04.027
更新日期:2017-05-01 00:00:00
abstract::The presence and distribution of cholecystokinin (CCK)/gastrin-like immunoreactivity (IR) was examined in the goldfish pituitary. Intense CCK/gastrin-like IR was consistently observed within fibers of the proximal pars distalis (PD), with fewer IR fibers localized in the rostral PD. Within the proximal PD CCK/gastrin-...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1006/gcen.1993.1146
更新日期:1993-10-01 00:00:00
abstract::Determination of serum progesterone concentrations over a period of 2 years in female camels during various reproductive stages (estrus, pregnant, nonpregnant, and lactating) suggests that the progesterone levels exceeding 1 ng/ml are reached only if mating is fertile. A cycling camel does not have a luteal phase and ...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/0016-6480(84)90248-x
更新日期:1984-02-01 00:00:00
abstract::The neuropeptide gonadotropin-releasing hormone (GnRH) plays an important role in the control of reproductive functions. Vertebrates possess multiple GnRH isoforms that are classified into three main groups, namely GnRH1, GnRH2 and GnRH3. In the present study, we show that the chromosomal organization of the three GnR...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/j.ygcen.2010.11.017
更新日期:2011-02-01 00:00:00
abstract::The adenohypophysial cell types in three species of sciaenid teleosts were identified using a combination of classical histochemical techniques and immunocytochemistry with antisera raised against piscine and human pituitary hormones. In general greater specificity for the different cell types was observed with antise...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/0016-6480(91)90086-l
更新日期:1991-12-01 00:00:00
abstract::The binding of 125I-labeled ovine prolactin (oPRL) to membrane preparations of tissue from freshwater-adapted tilapia (Sarotherodon mossambicus) was examined. Liver, ovary, and testis showed a relatively high specific binding (5-10%). A lower specific binding occurred consistently in intestine and gill tissue, and inc...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/0016-6480(84)90056-x
更新日期:1984-10-01 00:00:00
abstract::The social environment of reproducing females can cause physiological changes, with consequences for reproductive investment and offspring development. These prenatal maternal effects are often found to be sex-specific and may have evolved as adaptations, maximizing fitness of male and female offspring for their futur...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/j.ygcen.2018.04.015
更新日期:2018-07-01 00:00:00
abstract::The discovery of novel members of the CRF neuropeptide family, urocortin 1 (Ucn1), urocortin 2 and 3 has provided important insights into stress adaptation pathways, and predicted that stress adaptation involves more systems than the HPA-axis alone. This mini-review aims to summarize our recent data and research by ot...
journal_title:General and comparative endocrinology
pub_type: 杂志文章,评审
doi:10.1016/j.ygcen.2007.04.005
更新日期:2007-08-01 00:00:00
abstract::The developmental sequence of markers for hematopoietic, hormone-producing, and folliculo-stellate cells in the chicken adenohypophysis is described using immunohistochemical staining techniques. Hematopoietic cells are detected in cryosections of the adenohypophysis starting from 10- or 12-day embryos, using chicken-...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1006/gcen.1998.7235
更新日期:1999-05-01 00:00:00
abstract::Triorganotins, such as tributyltin chloride (TBTCl), are environmental contaminants that are commonly found in the antifouling paints used in ships and other vessels. The importance of TBTCl as an endocrine-disrupting chemical (EDC) in different animal models is well known; however, its adverse effects on the thyroid ...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/j.ygcen.2014.07.027
更新日期:2014-09-15 00:00:00
abstract::GPCRs are the largest family of receptors accounting for about 30% of the current drug targets. However, it is difficult to fully elucidate the mechanisms regulating intracellular GPCR signal regulation. It is thus important to consider and investigate GPCRs with respect to endogenous situations. Our group has been in...
journal_title:General and comparative endocrinology
pub_type: 杂志文章,评审
doi:10.1016/j.ygcen.2020.113474
更新日期:2020-07-01 00:00:00
abstract::In dairy cows, heat stress depresses appetite, leading to decreased food intake, a negative energy balance, and modifies ghrelin levels. Ghrelin is a gut-brain peptide with two major forms: acylated, with an O-n-octanoylated serine in position 3, and nonacylated. To date, the effect of heat stress and estrous cycle on...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/j.ygcen.2016.06.006
更新日期:2016-09-01 00:00:00
abstract::The total cortisol content in tilapia was 55 pg immediately following fertilization, then decreased abruptly and maintained a lower level of 10-20 pg until hatching; after hatching the cortisol content increased to 50 pg by the 7th day. Fertilized eggs were incubated in either 32% saltwater or fresh water and sampled ...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1006/gcen.1993.1168
更新日期:1993-11-01 00:00:00
abstract::It is known that in goldfish Carassius auratus, a non-sex changing fish, prostaglandin (PG) treatment can induce female-typical sex behavior in males, and androgen treatment can induce male-typical sex behavior in females. These facts suggest that goldfish have a sexually bipotential brain even after attaining sexual ...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/j.ygcen.2012.08.022
更新日期:2013-01-15 00:00:00
abstract::Several neuropeptides possessing the RFamide motif at their C-termini (designated RFamide peptides) have been characterized in the hypothalamus of a variety of vertebrates. Since the discovery of the 26-amino acid RFamide peptide (termed 26RFa) from the frog brain, 26RFa has been shown to exert orexigenic activity in ...
journal_title:General and comparative endocrinology
pub_type: 杂志文章,评审
doi:10.1016/j.ygcen.2013.03.014
更新日期:2013-09-01 00:00:00
abstract::In hamsters, the Harderian glands (HGs) exhibit a marked sexual dimorphism which is thought to depend on dihydrotestosterone (DHT); however, it is unclear whether hamster HGs contain one or more 5 alpha-reductases and whether these enzymes are differentially expressed in males and females. In this study, we isolated s...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/j.ygcen.2009.12.010
更新日期:2010-04-01 00:00:00
abstract::The aim of our study was to confirm the role of tidal pattern on the coordination of oocyte maturation and spawning in common snook Centropomus undecimalis. To do so, we studied oocyte maturation during the spawning season in relation to the tidal pattern in both males and females by means of histology and hormonal pr...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/j.ygcen.2015.08.007
更新日期:2015-12-01 00:00:00
abstract::The activities of oxidative enzymes of hepatic mitochondria of Anabas testudineus increased following exogenous administration of hydrocortisone and corticosterone. The inhibitors of protein synthesis prevented the hormone-mediated increase of hepatic enzymes, suggesting that corticosteroids regulate the oxidative met...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/0016-6480(90)90017-g
更新日期:1990-05-01 00:00:00
abstract::The possible involvement of calcium in the regulation of steroidogenesis in the goldfish was investigated using preovulatory ovarian follicles incubated in vitro. Incubation of follicles in media deficient in calcium impaired testosterone production in response to human chorionic gonadotropin (hCG) in both the presenc...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/0016-6480(91)90011-t
更新日期:1991-02-01 00:00:00
abstract::The presence of specific, saturable, high-affinity gonadotropin receptors was demonstrated in membrane preparations from preovulatory ovarian follicles of amago salmon (Oncorhynchus rhodurus), including intact follicles, isolated thecal layers, and isolated granulosa cells. Optimum conditions for the binding study usi...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/0016-6480(88)90177-3
更新日期:1988-10-01 00:00:00
abstract::Ovaprim (OVP) is used as an effective spawning inducer for artificial breeding of fishes and contains a salmon gonadotropin-releasing hormone analogue and a dopamine receptor-2 antagonist, domperidone. Previously, we have shown that vasotocin (VT) stimulates ovarian final oocyte maturation, hydration, and ovulation th...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/j.ygcen.2013.11.009
更新日期:2014-01-01 00:00:00
abstract::Testosterone has been suggested to be involved in the regulation of male territorial behavior. For example, seasonal peaks in testosterone typically coincide with periods of intense competition between males for territories and mating partners. However, some species also express territorial behavior outside a breeding...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/j.ygcen.2012.11.027
更新日期:2013-04-01 00:00:00