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Guagnoni IN, Armelin VA, da Silva Braga VH, Monteiro DA, Florindo LH. Cardiovascular responses and the role of the neurohumoral cardiac regulation during digestion in the herbivorous lizard Iguana iguana. J Exp Biol 2024; 227:jeb247105. [PMID: 38186316 DOI: 10.1242/jeb.247105] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 12/27/2023] [Indexed: 01/09/2024]
Abstract
Carnivorous reptiles exhibit an intense metabolic increment during digestion, which is accompanied by several cardiovascular adjustments responsible for meeting the physiological demands of the gastrointestinal system. Postprandial tachycardia, a well-documented phenomenon in these animals, is mediated by the withdrawal of vagal tone associated with the chronotropic effects of non-adrenergic and non-cholinergic (NANC) factors. However, herbivorous reptiles exhibit a modest metabolic increment during digestion and there is no information about postprandial cardiovascular adjustments. Considering the significant impact of feeding characteristics on physiological responses, we investigated cardiovascular and metabolic responses, as well as the neurohumoral mechanisms of cardiac control, in the herbivorous lizard Iguana iguana during digestion. We measured oxygen consumption rate (O2), heart rate (fH), mean arterial blood pressure (MAP), myocardial activity, cardiac autonomic tone, fH/MAP variability and baroreflex efficiency in both fasting and digesting animals before and after parasympathetic blockade with atropine followed by double autonomic blockade with atropine and propranolol. Our results revealed that the peak of O2 in iguanas was reached 24 h after feeding, accompanied by an increase in myocardial activity and a subtle tachycardia mediated exclusively by a reduction in cardiac parasympathetic activity. This represents the first reported case of postprandial tachycardia in digesting reptiles without the involvement of NANC factors. Furthermore, this withdrawal of vagal stimulation during digestion may reduce the regulatory range for short-term fH adjustments, subsequently intensifying the blood pressure variability as a consequence of limiting baroreflex efficiency.
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Affiliation(s)
- Igor Noll Guagnoni
- Department of Biological Sciences, São Paulo State University (UNESP), Rua Cristóvão Colombo, 2265, São José do Rio Preto, SP 15054-000, Brazil
- National Institute of Science and Technology in Comparative Physiology (INCT - FAPESP/CNPq), São Paulo, SP 13506-900, Brazil
| | - Vinicius Araújo Armelin
- Department of Biological Sciences, São Paulo State University (UNESP), Rua Cristóvão Colombo, 2265, São José do Rio Preto, SP 15054-000, Brazil
- National Institute of Science and Technology in Comparative Physiology (INCT - FAPESP/CNPq), São Paulo, SP 13506-900, Brazil
- Department of Physiology, Institute of Biosciences (IB), University of São Paulo (USP), São Paulo, SP 05508-090, Brazil
| | - Victor Hugo da Silva Braga
- Department of Biological Sciences, São Paulo State University (UNESP), Rua Cristóvão Colombo, 2265, São José do Rio Preto, SP 15054-000, Brazil
- National Institute of Science and Technology in Comparative Physiology (INCT - FAPESP/CNPq), São Paulo, SP 13506-900, Brazil
| | - Diana Amaral Monteiro
- Department of Physiological Sciences, Federal University of São Carlos (UFSCar), Rodovia Washington Luiz, km 235, São Carlos, SP 13565-905, Brazil
| | - Luiz Henrique Florindo
- Department of Biological Sciences, São Paulo State University (UNESP), Rua Cristóvão Colombo, 2265, São José do Rio Preto, SP 15054-000, Brazil
- National Institute of Science and Technology in Comparative Physiology (INCT - FAPESP/CNPq), São Paulo, SP 13506-900, Brazil
- Department of Physiological Sciences, Federal University of São Carlos (UFSCar), Rodovia Washington Luiz, km 235, São Carlos, SP 13565-905, Brazil
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2
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Baroreflex responses to activity at different temperatures in the South American rattlesnake, Crotalus durissus. J Comp Physiol B 2021; 191:917-925. [PMID: 34363512 DOI: 10.1007/s00360-021-01396-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 07/15/2021] [Accepted: 07/30/2021] [Indexed: 10/20/2022]
Abstract
In humans, physical exercise imposes narrower limits for the heart rate (fH) response of the baroreflex, and vascular modulation becomes largely responsible for arterial pressure regulation. In undisturbed reptiles, the baroreflex-related fH alterations at the operating point (Gop) decreases at elevated body temperatures (Tb) and the vascular regulation changes accordingly. We investigated how the baroreflex of rattlesnakes, Crotalus durissus, is regulated during an activity at different Tb, expecting that activity would reduce the capacity of the cardiac baroreflex neural pathway to buffer arterial pressure fluctuations while being compensated by the vascular neural pathway regulation. Snakes were catheterized for blood pressure assessment at three different Tb: 15, 20 and 30 °C. Data were collected before and after activity at each Tb. Baroreflex gain (Gop) was assessed with the sequence method; the vascular limb, with the time constant of pressure decay (τ), using the two-element Windkessel equation. Both Gop and τ reduced when Tb increased. Activity also reduced Gop and τ in all Tb. The relationship between τ and pulse interval (τ/PI) was unaffected by the temperature at resting snakes, albeit it reduced after activity at 20 °C and 30 °C. The unchanged τ/PI and normalized Gop at different Tb indicated those variables are actively adjusted to work at different fH and pressure conditions at rest. Our data suggest that during activity, the baroreflex-related fH response is attenuated and hypertension is buffered by a disproportional increase in the rate which pressure decays during diastole. This compensation seems especially important at higher Tb where Gop is already low.
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Armelin VA, Braga VHDS, Teixeira MT, Guagnoni IN, Wang T, Florindo LH. The nonpharmacological sequence method provides a reliable evaluation of baroreflex sensitivity in fish. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2021; 335:348-358. [PMID: 33503334 DOI: 10.1002/jez.2448] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 12/22/2020] [Accepted: 01/08/2021] [Indexed: 11/10/2022]
Abstract
The most commonly used technique to study the barostatic regulation of blood pressure in ectothermic vertebrates consists of determining the heart rate response to pharmacological manipulations of blood pressure, the so-called "Oxford method." Although well established, the Oxford method has some important limitations, such as induction of hypervolemia in small animals and undesired effects of vasoactive drugs on central and peripheral baroreflex components. As an alternative, the sequence method, which consists in the computerized evaluation of naturally-occurring baroreflex adjustments of heart rate without the need for pharmacological administrations, was developed to study baroreflexes. In the present study, we compare this sequence method with the Oxford technique in two teleost species with different life styles, and we assess the optimal software configuration for the employment of the sequence method in fish. Calculation of baroreflex gain through the sequence method was adequate and reliable when the software was configured to search for baroreflex sequences with a minimum length of three cardiac cycles with a delay of one cardiac cycle between fluctuations in mean ventral aortic blood pressure and reflex changes in pulse interval. When properly configured, the sequence and the Oxford methods yielded similar determinations of the baroreflex gain in fish.
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Affiliation(s)
- Vinicius A Armelin
- Department of Physiology, University of São Paulo (USP), São Paulo, SP, Brazil.,Department of Zoology and Botany, São Paulo State University (UNESP), São José do Rio Preto, SP, Brazil.,National Institute of Science and Technology in Comparative Physiology (INCT-FAPESP/CNPq), Rio Claro, SP, Brazil
| | - Victor H da Silva Braga
- Department of Zoology and Botany, São Paulo State University (UNESP), São José do Rio Preto, SP, Brazil.,National Institute of Science and Technology in Comparative Physiology (INCT-FAPESP/CNPq), Rio Claro, SP, Brazil
| | - Mariana T Teixeira
- Department of Zoology and Botany, São Paulo State University (UNESP), São José do Rio Preto, SP, Brazil.,National Institute of Science and Technology in Comparative Physiology (INCT-FAPESP/CNPq), Rio Claro, SP, Brazil
| | - Igor N Guagnoni
- Department of Zoology and Botany, São Paulo State University (UNESP), São José do Rio Preto, SP, Brazil.,National Institute of Science and Technology in Comparative Physiology (INCT-FAPESP/CNPq), Rio Claro, SP, Brazil
| | - Tobias Wang
- National Institute of Science and Technology in Comparative Physiology (INCT-FAPESP/CNPq), Rio Claro, SP, Brazil.,Section for Zoophysiology, Department of Bioscience, Aarhus University (AU), Aarhus, Denmark
| | - Luiz H Florindo
- Department of Zoology and Botany, São Paulo State University (UNESP), São José do Rio Preto, SP, Brazil.,National Institute of Science and Technology in Comparative Physiology (INCT-FAPESP/CNPq), Rio Claro, SP, Brazil.,Aquaculture Center (CAUNESP), São Paulo State University (UNESP), Jaboticabal, SP, Brazil
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4
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Filogonio R, Orsolini KF, Oda GM, Malte H, Leite CAC. Baroreflex gain and time of pressure decay at different body temperatures in the tegu lizard, Salvator merianae. PLoS One 2020; 15:e0242346. [PMID: 33227002 PMCID: PMC7682859 DOI: 10.1371/journal.pone.0242346] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 11/01/2020] [Indexed: 12/20/2022] Open
Abstract
Ectotherms may experience large body temperature (Tb) variations. Higher Tb have been reported to increase baroreflex sensitivity in ectotherm tetrapods. At lower Tb, pulse interval (PI) increases and diastolic pressure decays for longer, possibly resulting in lower end-diastolic pressures and mean arterial pressures (Pm). Additionally, compensatory baroreflex-related heart rate modulation (i.e. the cardiac branch of the baroreflex response) is delayed due to increased PI. Thus, low Tb is potentially detrimental, leading to cardiovascular malfunctioning. This raises the question on how Pm is regulated in such an adverse condition. We investigated the baroreflex compensations that enables tegu lizards, Salvator merianae, to maintain blood pressure homeostasis in a wide Tb range. Lizards had their femoral artery cannulated and pressure signals recorded at 15°C, 25°C and 35°C. We used the sequence method to analyse the heart rate baroreflex-related corrections to spontaneous pressure fluctuations at each temperature. Vascular adjustments (i.e. the peripheral branch) were assessed by calculating the time constant for arterial pressure decay (τ)—resultant from the action of both vascular resistance and compliance—by fitting the diastolic pressure descent to the two-element Windkessel equation. We observed that at lower Tb, lizards increased baroreflex gain at the operating point (Gop) and τ, indicating that the diastolic pressure decays at a slower rate. Gop normalized to Pm and PI, as well as the ratio τ/PI, did not change, indicating that both baroreflex gain and rate of pressure decay are adjusted according to PI lengthening. Consequently, pressure parameters and the oscillatory power fraction (an index of wasted cardiac energy) were unaltered by Tb, indicating that both Gop and τ modulation are crucial for cardiovascular homeostasis.
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Affiliation(s)
- Renato Filogonio
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, São Paulo, Brazil
- * E-mail:
| | - Karina F. Orsolini
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, São Paulo, Brazil
| | - Gustavo M. Oda
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, São Paulo, Brazil
| | - Hans Malte
- Section for Zoophysiology, Department of Bioscience, Aarhus University, Aarhus C, Denmark
| | - Cléo A. C. Leite
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, São Paulo, Brazil
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Niu Y, Cao W, Storey KB, He J, Wang J, Zhang T, Tang X, Chen Q. Metabolic characteristics of overwintering by the high-altitude dwelling Xizang plateau frog, Nanorana parkeri. J Comp Physiol B 2020; 190:433-444. [PMID: 32274534 DOI: 10.1007/s00360-020-01275-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 03/20/2020] [Accepted: 03/27/2020] [Indexed: 12/12/2022]
Abstract
The Xizang plateau frog, Nanorana parkeri, has the highest altitudinal distribution of all frogs in the world and survives the cold of winter without feeding by entering into a hibernating state. However, little attention has been paid to its physiological and biochemical characteristics that support overwintering underwater in small ponds. Here, we measured metabolic rate and heart rate, and collected liver and muscle samples from N. parkeri in summer and winter for analysis of mitochondrial respiration rate, and activities and relative mRNA transcript expression of metabolic enzymes. Compared with summer-collected frogs, both resting metabolic rate and heart rate were significantly reduced in winter-collected frogs. Both state 3 and state 4 respiration of liver mitochondria were also significantly reduced in winter but muscle mitochondria showed a decline only in state 3 respiration in winter. The activities and corresponding mRNA expression of cytochrome c oxidase showed a marked decline in winter, whereas the activities and corresponding mRNA expression of lactate dehydrogenase increased in winter-collected frogs, compared to summer. The thermal sensitivity (Q10 values) for state 3 respiration rate by liver mitochondria, and activities of lactate dehydrogenase, and cytochrome c oxidase all increased in winter-collected frogs, compared with summer frogs, suggesting that overwintering frogs were more sensitive to changes in external temperature. Enzyme changes mainly result from lower overall quantities of these enzymes as well as post-translational modifications. We conclude that overwintering N. parkeri exhibit a seasonal, temperature-independent suppression of metabolism that is mediated at multiple levels: physiological, mitochondrial, gene expression and enzyme activity levels.
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Affiliation(s)
- Yonggang Niu
- School of Life Sciences, Dezhou University, Dezhou, China.,Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, China.,State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, China
| | - Wangjie Cao
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, China
| | - Kenneth B Storey
- Department of Biology, Carleton University, Ottawa, ON, K1S 5B6, Canada
| | - Jie He
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, China
| | - Jinzhou Wang
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, China
| | - Tao Zhang
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, China
| | - Xiaolong Tang
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, China
| | - Qiang Chen
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, China. .,State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, China.
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Zena LA, Dillon D, Hunt KE, Navas CA, Buck CL, Bícego KC. Hormonal correlates of the annual cycle of activity and body temperature in the South-American tegu lizard (Salvator merianae). Gen Comp Endocrinol 2020; 285:113295. [PMID: 31580883 DOI: 10.1016/j.ygcen.2019.113295] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 08/19/2019] [Accepted: 09/29/2019] [Indexed: 01/29/2023]
Abstract
Life history transitions and hormones are known to interact and influence many aspects of animal physiology and behavior. The South-American tegu lizard (Salvator merianae) exhibits a profound seasonal shift in metabolism and body temperature, characterized by high daily activity during warmer months, including reproductive endothermy in spring, and metabolic suppression during hibernation in winter. This makes S. merianae an interesting subject for studies of interrelationships between endocrinology and seasonal changes in physiology/behavior. We investigated how plasma concentrations of hormones involved in regulation of energy metabolism (thyroid hormones T4 and T3; corticosterone) and reproduction (testosterone in males and estrogen/progesterone in females) correlate with activity and body temperature (Tb) across the annual cycle of captive held S. merianae in semi-natural conditions. In our initial model, thyroid hormones and corticosterone showed a positive relationship with activity and Tb with independent of sex: T3 positively correlated with activity and Tb, while T4 and corticosterone correlated positively with changes in Tb only. This suggests that thyroid hormones and glucocorticoids may be involved in metabolic transitions of annual cycle events. When accounting for sex-steroid hormones, our sex separated models showed a positive relationship between testosterone and Tb in males and progesterone and activity in females. Coupling seasonal endocrine measures with activity and Tb may expand our understanding of the relationship between animal's physiology and its environment. Manipulative experiments are required in order to unveil the directionality of influences existing among abiotic factors and the hormonal signaling of annual cyclicity in physiology/behavior.
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Affiliation(s)
- Lucas A Zena
- Department of Physiology, Institute of Biosciences, University of São Paulo, 05508-090 São Paulo, SP, Brazil; Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA.
| | - Danielle Dillon
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - Kathleen E Hunt
- Department of Biology, George Mason University, Fairfax, VA, USA
| | - Carlos A Navas
- Department of Physiology, Institute of Biosciences, University of São Paulo, 05508-090 São Paulo, SP, Brazil
| | - C Loren Buck
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - Kênia C Bícego
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, 14884-900 Jaboticabal, São Paulo, Brazil.
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Burggren W, Filogonio R, Wang T. Cardiovascular shunting in vertebrates: a practical integration of competing hypotheses. Biol Rev Camb Philos Soc 2019; 95:449-471. [PMID: 31859458 DOI: 10.1111/brv.12572] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 10/30/2019] [Accepted: 11/07/2019] [Indexed: 12/20/2022]
Abstract
This review explores the long-standing question: 'Why do cardiovascular shunts occur?' An historical perspective is provided on previous research into cardiac shunts in vertebrates that continues to shape current views. Cardiac shunts and when they occur is then described for vertebrates. Nearly 20 different functional reasons have been proposed as specific causes of shunts, ranging from energy conservation to improved gas exchange, and including a plethora of functions related to thermoregulation, digestion and haemodynamics. It has even been suggested that shunts are merely an evolutionary or developmental relic. Having considered the various hypotheses involving cardiovascular shunting in vertebrates, this review then takes a non-traditional approach. Rather than attempting to identify the single 'correct' reason for the occurrence of shunts, we advance a more holistic, integrative approach that embraces multiple, non-exclusive suites of proposed causes for shunts, and indicates how these varied functions might at least co-exist, if not actually support each other as shunts serve multiple, concurrent physiological functions. It is argued that deposing the 'monolithic' view of shunting leads to a more nuanced view of vertebrate cardiovascular systems. This review concludes by suggesting new paradigms for testing the function(s) of shunts, including experimentally placing organ systems into conflict in terms of their perfusion needs, reducing sources of variation in physiological experiments, measuring possible compensatory responses to shunt ablation, moving experiments from the laboratory to the field, and using cladistics-related approaches in the choice of experimental animals.
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Affiliation(s)
- Warren Burggren
- Department of Biological Sciences, Developmental Integrative Biology Cluster, University of North Texas, Denton, TX, 76203-5220, U.S.A
| | - Renato Filogonio
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, SP, 13565-905, Brazil
| | - Tobias Wang
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus C, 8000, Denmark.,Aarhus Institute of Advanced Sciences (AIAS), Aarhus University, Aarhus C, 8000, Denmark
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8
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Cardiovascular and ventilatory interactions in the facultative air-breathing teleost Pangasianodon hypophthalmus. J Comp Physiol B 2019; 189:425-440. [DOI: 10.1007/s00360-019-01225-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 05/20/2019] [Accepted: 06/24/2019] [Indexed: 02/07/2023]
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9
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Filogonio R, Orsolini KF, Castro SA, Oda GM, Rocha GC, Tavares D, Abe AS, Leite CAC. Evaluation of the sequence method as a tool to assess spontaneous baroreflex in reptiles. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2019; 331:374-381. [DOI: 10.1002/jez.2273] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 05/09/2019] [Indexed: 01/22/2023]
Affiliation(s)
- Renato Filogonio
- Department of Physiological Sciences; Federal University of São Carlos (UFSCar); São Carlos São Paulo Brazil
| | - Karina F. Orsolini
- Department of Physiological Sciences; Federal University of São Carlos (UFSCar); São Carlos São Paulo Brazil
| | - Samanta A. Castro
- Department of Physiological Sciences; Federal University of São Carlos (UFSCar); São Carlos São Paulo Brazil
| | - Gustavo M. Oda
- Department of Physiological Sciences; Federal University of São Carlos (UFSCar); São Carlos São Paulo Brazil
| | - Gabriella C. Rocha
- Department of Physiological Sciences; Federal University of São Carlos (UFSCar); São Carlos São Paulo Brazil
| | - Driele Tavares
- Department of Physiological Sciences; Federal University of São Carlos (UFSCar); São Carlos São Paulo Brazil
| | - Augusto S. Abe
- Department of Zoology; State University of São Paulo (UNESP); Rio Claro São Paulo Brazil
| | - Cléo A. C. Leite
- Department of Physiological Sciences; Federal University of São Carlos (UFSCar); São Carlos São Paulo Brazil
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Zena LA, Dillon D, Hunt KE, Navas CA, Bícego KC, Buck CL. Seasonal changes in plasma concentrations of the thyroid, glucocorticoid and reproductive hormones in the tegu lizard Salvator merianae. Gen Comp Endocrinol 2019; 273:134-143. [PMID: 29913170 DOI: 10.1016/j.ygcen.2018.06.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 05/16/2018] [Accepted: 06/15/2018] [Indexed: 12/21/2022]
Abstract
The tegu lizard Salvator merianae is a large, widely distributed teiid lizard endemic to South America that exhibits annual cycles of high activity during the spring and summer, and hibernation during winter. This pattern of activity and hibernation is accompanied by profound seasonal changes in physiology and behavior, including endothermy during the austral spring. The unusual combination of seasonal endothermy, hibernation and oviparity, in a non-avian, non-mammalian species, makes S. merianae an interesting subject for study of comparative aspects of endocrine regulation of seasonal changes in physiology. In the present study, we first validated commercially available immunoassay kits for quantification of hormone concentrations of the reproductive (testosterone, estradiol and progesterone), adrenal (corticosterone), and thyroid [thyroxine (T4) and triiodothyronine (T3)] axes in plasma of an outdoor, captive adult male and female S. merianae in southeastern Brazil. All assays exhibited parallelism and accuracy with S. merianae plasma. We next assessed patterns of concentration of these hormones across the annual cycle of S. merianae. Testosterone in males and estradiol in females peaked in spring coincident with the peak in reproductive behavior. Progesterone in females was significantly elevated in October coincident with putative ovulation when gravid females build nests. Thyroid hormones, known for regulating energy metabolism, varied seasonally with some sex-dependent differences. T4 gradually increased from an annual nadir during pre-hibernation and hibernation to high concentrations during spring in both sexes. In contrast, T3 did not vary seasonally in males, but females showed a two-fold increase in T3 during the spring reproductive season. T3 may be involved in energy investment during the seasonal production of large clutches of eggs. Corticosterone was significantly elevated during the active season in both sexes, suggesting its involvement in mobilization of energy stores and modulation of behavior (territoriality) and physiology. Ours is the first investigation of concurrent changes in reproductive, thyroid and adrenal hormone concentrations in this endemic and physiologically unique South American lizard. Our findings set the stage for future investigations to determine the extent to which these hormones influence activity and thermoregulation in S. merianae.
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Affiliation(s)
- Lucas A Zena
- Department of Physiology, Institute of Biosciences, University of São Paulo, 05508-090 São Paulo, SP, Brazil; Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, 14884-900, Jaboticabal, São Paulo, Brazil; National Institute of Science and Technology in Comparative Physiology (INCT Fisiologia Comparada), Brazil.
| | - Danielle Dillon
- Department of Biological Sciences, Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ, USA
| | - Kathleen E Hunt
- Department of Biological Sciences, Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ, USA
| | - Carlos A Navas
- Department of Physiology, Institute of Biosciences, University of São Paulo, 05508-090 São Paulo, SP, Brazil
| | - Kênia C Bícego
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, 14884-900, Jaboticabal, São Paulo, Brazil; National Institute of Science and Technology in Comparative Physiology (INCT Fisiologia Comparada), Brazil
| | - C Loren Buck
- Department of Biological Sciences, Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ, USA.
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Longhini LS, Zena LA, da Silva GSF, Bícego KC, Gargaglioni LH. Temperature effects on the cardiorespiratory control of American bullfrog tadpoles based on a non-invasive methodology. ACTA ACUST UNITED AC 2017; 220:3763-3770. [PMID: 28819055 DOI: 10.1242/jeb.160911] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Accepted: 08/14/2017] [Indexed: 11/20/2022]
Abstract
Temperature effects on cardiac autonomic tonus in amphibian larval stages have never been investigated. Therefore, we evaluated the effect of different temperatures (15, 25 and 30°C) on the cardiorespiratory rates and cardiac autonomic tonus of premetamorphic tadpoles of the bullfrog, Lithobates catesbeianus To this end, a non-invasive method was developed to permit measurements of electrocardiogram (ECG) and buccal movements (fB; surface electromyography of the buccal floor). For evaluation of autonomic regulation, intraperitoneal injections of Ringer solution (control), atropine (cholinergic muscarinic antagonist) and sotalol (β-adrenergic antagonist) were performed. Ringer solution injections did not affect heart rate (fH) or fB across temperatures. Cardiorespiratory parameters were significantly augmented by temperature (fH: 24.5±1.0, 54.5±2.0 and 75.8±2.8 beats min-1 at 15, 25 and 30°C, respectively; fB: 30.3±1.1, 73.1±4.0 and 100.6±3.7 movements min-1 at 15, 25 and 30°C, respectively). A predominant vagal tone was observed at 15°C (32.0±3.2%) and 25°C (27.2±6.7%) relative to the adrenergic tone. At 30°C, the adrenergic tone increased relative to the lower temperature. In conclusion, the cholinergic and adrenergic tones seem to be independent of temperature for colder thermal intervals (15-25°C), while exposure to a hotter ambient temperature (30°C) seems to be followed by a significant increase in adrenergic tone and may reflect cardiovascular adjustments made to match oxygen delivery to demand. Furthermore, while excluding the use of implantable electrodes or cannulae, this study provides a suitable non-invasive method for investigating cardiorespiratory function (cardiac and respiratory rates) in water-breathing animals such as the tadpole.
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Affiliation(s)
- Leonardo S Longhini
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, 14884-900, Jaboticabal, São Paulo, Brazil
| | - Lucas A Zena
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, 14884-900, Jaboticabal, São Paulo, Brazil .,National Institute of Science and Technology in Comparative Physiology (INCT Fisiologia Comparada), Brazil
| | - Glauber S F da Silva
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, 14884-900, Jaboticabal, São Paulo, Brazil.,National Institute of Science and Technology in Comparative Physiology (INCT Fisiologia Comparada), Brazil
| | - Kênia C Bícego
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, 14884-900, Jaboticabal, São Paulo, Brazil.,National Institute of Science and Technology in Comparative Physiology (INCT Fisiologia Comparada), Brazil
| | - Luciane H Gargaglioni
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, 14884-900, Jaboticabal, São Paulo, Brazil .,National Institute of Science and Technology in Comparative Physiology (INCT Fisiologia Comparada), Brazil
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Braga VHDS, Armelin VA, Teixeira MT, Abe AS, Rantin FT, Florindo LH. The Effects of Feeding on Cardiac Control of the Broad-Nosed Caiman (Caiman latirostris): The Role of the Autonomic Nervous System and NANC Factors. ACTA ACUST UNITED AC 2016; 325:524-531. [DOI: 10.1002/jez.2036] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 07/06/2016] [Accepted: 08/05/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Victor Hugo Da Silva Braga
- Department of Zoology and Botany; São Paulo State University (UNESP); São José do Rio Preto São Paulo Brazil
- National Institute of Science and Technology in Comparative Physiology (INCT-FAPESP/CNPq); São Paulo Brazil
| | - Vinicius Araújo Armelin
- Department of Zoology and Botany; São Paulo State University (UNESP); São José do Rio Preto São Paulo Brazil
- National Institute of Science and Technology in Comparative Physiology (INCT-FAPESP/CNPq); São Paulo Brazil
| | - Mariana Teodoro Teixeira
- Department of Zoology and Botany; São Paulo State University (UNESP); São José do Rio Preto São Paulo Brazil
- National Institute of Science and Technology in Comparative Physiology (INCT-FAPESP/CNPq); São Paulo Brazil
| | - Augusto Shinya Abe
- National Institute of Science and Technology in Comparative Physiology (INCT-FAPESP/CNPq); São Paulo Brazil
- Department of Zoology; São Paulo State University (UNESP); Rio Claro São Paulo Brazil
- Aquaculture Center (CAUNESP); São Paulo State University (UNESP); Jaboticabal São Paulo Brazil
| | - Francisco Tadeu Rantin
- National Institute of Science and Technology in Comparative Physiology (INCT-FAPESP/CNPq); São Paulo Brazil
- Department of Physiological Sciences; Federal University of São Carlos (UFSCar); São Carlos, São Paulo Brazil
| | - Luiz Henrique Florindo
- Department of Zoology and Botany; São Paulo State University (UNESP); São José do Rio Preto São Paulo Brazil
- National Institute of Science and Technology in Comparative Physiology (INCT-FAPESP/CNPq); São Paulo Brazil
- Aquaculture Center (CAUNESP); São Paulo State University (UNESP); Jaboticabal São Paulo Brazil
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Zena LA, da Silva GSF, Gargaglioni LH, Bícego KC. Baroreflex regulation affects ventilation in the Cururu toad Rhinella schneideri. J Exp Biol 2016; 219:3605-3615. [DOI: 10.1242/jeb.144774] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 08/31/2016] [Indexed: 10/21/2022]
Abstract
Anurans regulate short-term oscillations in blood pressure through changes in heart rate (fH), vascular resistance and lymph hearts frequency. Lung ventilation in anurans is linked to blood volume homeostasis by facilitating lymph return to the cardiovascular system. We hypothesized that the arterial baroreflex modulates pulmonary ventilation in the Cururu toad Rhinella schneideri, and that this relationship is temperature-dependent. Pharmacologically induced hypotension (sodium nitroprusside) and hypertension (phenylephrine) increased ventilation (25°C: 248.7±25.7; 35°C: 351.5±50.2 ml kg−1 min−1) and decreased ventilation (25°C: 9.0±6.6; 35°C: 50.7±15.6 ml kg−1 min−1), respectively, relative to control values from Ringer's injection (25°C: 78.1±17.0; 35°C: 137.7±15.5 ml kg−1 min−1). The sensitivity of the ventilatory response to blood pressure changes was higher during hypotension than hypertension (25°C: -97.6±17.1 vs. -23.6±6.0 breaths min−1 kPa−1; 35°C: -141.0±29.5 vs. -28.7±6.4 breaths min−1 kPa−1, respectively), while temperature had no effect on those sensitivities. Hyperoxia (30%; 25°C) diminished ventilation, but did not abolish the ventilatory response to hypotension, indicating a response independent of peripheral chemoreceptors. Although there are previous data showing increased fH baroreflex sensitivity from 15 to 30°C in this species, further increases in temperature (35°C) diminished fH baroreflex gain (40.5±5.62 vs. 21.6±4.64 % kPa−1). Therefore, besides a pulmonary ventilation role in matching O2 delivery to demand at higher temperatures in anurans, it also plays a role in blood pressure regulation, independent of temperature, possibly owing to an interaction between baroreflex and respiratory areas in the brain, as previously suggested for mammals.
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Affiliation(s)
- Lucas A. Zena
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, 14884-900, Jaboticabal, São Paulo, Brazil
- National Institute of Science and Technology in Comparative Physiology (INCT Fisiologia Comparada), 14884-900, Jaboticabal, São Paulo, Brazil
| | - Glauber S. F. da Silva
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, 14884-900, Jaboticabal, São Paulo, Brazil
- National Institute of Science and Technology in Comparative Physiology (INCT Fisiologia Comparada), 14884-900, Jaboticabal, São Paulo, Brazil
| | - Luciane H. Gargaglioni
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, 14884-900, Jaboticabal, São Paulo, Brazil
- National Institute of Science and Technology in Comparative Physiology (INCT Fisiologia Comparada), 14884-900, Jaboticabal, São Paulo, Brazil
| | - Kênia C. Bícego
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, 14884-900, Jaboticabal, São Paulo, Brazil
- National Institute of Science and Technology in Comparative Physiology (INCT Fisiologia Comparada), 14884-900, Jaboticabal, São Paulo, Brazil
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