Search

Made available in DSpace on 2022-04-29T08:28:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 Introduction: The prenatal period is highly sensitive to pharmacological interventions. The psychoactive compounds of Cannabis act directly on the endocannabinoid system, and the deleterious effects of external cannabinoids during gestation may be related to negative interference in the central nervous system (CNS) formation, structuring and functioning of the respiratory system. Nevertheless, the influence of external cannabinoids on the ventilatory network development as well as in the chemosensitivity and the future consequences during neonatal and juvenile period is still unclear. Objective: To evaluate the effects of exposure to cannabinoid during the whole gestational period on the respiratory control system at P0, P6-7, P12-13 and P27-28 male and female rats. Material and Methods: Osmotic pumps were implanted subcutaneously in pregnant rats at embryonic day 0 and delivered vehicle (VEH) or CB1 receptor agonist (WIN 55212-2, 0.5 mg/Kg/day) for 21 days. Ventilation (VE) of animals was recorded by pressure-plethysmography (P0, P6-7 and P12-13) and whole body plethysmography (P27-28) during normoxia, hypercapnia (7% CO2) and hypoxia (10% O2), as well as the O2 consumption (VO2) was measured. Results: At P0, WIN-treated male rats had a higher resting ventilation (~45%), hypercapnic (HCVR, ~41%) and hypoxic ventilatory response (HVR, ~35%) compared to vehicle group. At P6-7, WIN male group had a decreased HCVR (~19%) and also a lower HVR (~16%). For P12-13 animals, both male and female WIN-treated rats had an increase in the response to CO2 (male-33% and female-18%). For P27-28 rats, the HCVR was significantly higher for male (~21%) as well as for female (~25%) WIN-treated groups, no difference was observed for HVR. All the respiratory changes observed were not caused by metabolic issues since no difference was observed in the VO2. Conclusions: A chronic and over activation of endocannabinoid system during gestation promotes alteration in the respiratory system development affecting the chemosensitivity to CO2 and O2 during neonatal and juvenile period. Financial support: FAPESP and CNPq. Dept of Animal Morphology and Physiology São Paulo State University FCAVJ Dept of Animal Morphology and Physiology São Paulo State University FCAVJ

Made available in DSpace on 2020-12-12T02:35:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Introduction: Cardiorespiratory studies in tadpols species are scarce, reflecting challenges of using invasive tools, for measuring heart rate (fH) and breathing frequency (fB) by means of implanting electrodes, cannulae, and others, especially in the case of long-term measurements. This study attempted to improve techniques previously used by Longhini and coworkers (2017) on measuring cardiorespiratory parameters non-invasively in bullfrog tadpoles in a much smaller anuran tadpole specie, Boana albopunctaca (Anura: Hylidae) from the Savannah-like Cerrado. This specie occurs in the central, southern and southeastern regions of Brazil in an area where deforestation levels are high. Objective: To determine the resting values for fH and fB of tadpoles (stage 26 from Gosner, 1960) B. albopunctata at 25°C using a non-invasive methodology. Additionally, we determined the Maximum Critical Temperature (CTmax) by exposing tadpoles to a heating ramp (1°C/4min). Material and Methods: Pre-metamorphic tadpoles (N=11) of Boana albopunctata were collected (SISBIO: 621361) in the Cerrado biome, in Minas Gerais state (20º 14' 43 S; 46º 21' 57 O), and maintained in the lab in aquariums at 25°C. The cardiorespiratory parameters, fH and fB, were obtained by a non-invasive electrocardiogram (ECG) and surface electromyogram (EMG) method, respectively. After baseline measurement, animals were handled in order to administer an intraperitoneal injection of Ringer solution (vehicle) to verify the influence of the injections on the basal cardiorespiratory parameters, which were recorded for an additional hour. For that, we used a thin dental needle (30 gauge) connected by a polyethylene tube (PE10, Clay Adams) to a Hamilton syringe (5 μl). The CTmax, the temperature at which animals lose the ability to escape from conditions that may ultimately lead to death, was determined by exposing tadpoles acclimatized at two different temperatures (15 and 25°C) to a constant heating rate of 1°C/4min. When the animals began to present loss of equilibrium, we stimulated them with a glass rod, and considered the CTmax when tadpoles were motionless after five consecutive taps. Immediately after assessing CTmax, we transferred tadpoles to plastic cups with water at ambient temperature (25°C). We validated the CTmax for individuals that remained alive for at least 24 h after the test. The data obtained were expressed as mean ± s. e. m. Results: At 25°C, baseline values for fH and fB were 104.6 ± 20.0 and 85.94 ± 18.9, respectively. Cardiorespiratory parameters were not significantly affected by the intraperitoneal Ringer solution injection: fH (beats.min−1): 103.2 ± 15.6 and fB (movements.min−1): 85.3 ± 16.1. Animals’ acclimatized at 20°C exhibited CTmax of 35.88 ± 1.58°C compared to those acclimatized at 30°C, with a CTmax of 39.57 ± 0.49°C. Conclusion: According to our preliminary results, we confirm that the non-invasive methodology adapted for larger tadpoles (e.g Bullfrog; size: ~9 cm) can be improved for measuring cardiorespiratory parameters non-invasively in small tadpoles (size: ~4 cm).After one hour from intraperitoneal ringer injection, fH and fB returned to their baseline values. Furthermore, animals acclimated to the higher temperature (30°C) showed greater thermal tolerance during a heating rate protocol. Sao Paulo State University FCAV/UNESP University of Sao Paulo Institute of Biosciences/USP Sao Paulo State University FCAV/UNESP FAPESP: 2018/01899-0