Biology subjects

Filogonio, R.

Publications and source records attributed to Filogonio, R..

3 recordsLinked to original sources

bioRxiv2026

Cold-acclimation, not motor inactivity, attenuates GABA signaling in the respiratory network of bullfrogs in response to overwintering

Neural circuits produce reliable activity even after environmental disturbances. This occurs because neurons respond to perturbations in a compensatory manner, a process termed homeostatic plasticity. Bullfrogs undergo prolonged periods underwater during winter, when lung ventilation and its neural control system ceases activity, but air-breathing resumes unscathed when environmental temperatures increase weeks to months later. Compensatory neural mechanisms that contribute involve upregulation of excitatory synaptic transmission on motoneurons driven by inactivity, but whether inactivity or acclimation to low temperatures drive other forms of compensation is not known. The GABAA receptor contribution to respiratory rhythm generation is downregulated following overwintering, which promotes network excitability. Therefore, we disentangled the contributions of cold temperature acclimation and inactivity experienced during overwintering on reduced GABAergic signaling. Here, we show that cold temperature, and not inactivity, reduces GABAA signaling in the respiratory rhythm generating network, without influencing GABAA transmission onto motoneurons. Therefore, cold temperature acclimation drives reduced GABAergic signaling selectively in inter-neuronal rhythm generating circuits, while excitatory motoneurons synapses are strengthened by inactivity in the overwintering environment. Most work interprets compensatory plasticity as activity-dependent during activity perturbations, but we reveal that different aspects of a disruptive environment elicit distinct forms of plasticity across a motor network.

neuroscience↗

bioRxiv2026

Activity-dependent homeostatic synaptic plasticity widens the temperature range of synaptic transmission

The framework of homeostatic plasticity posits that neurons regulate cellular properties through feedback homeostasis to maintain activity during changes in the environment. However, when disturbances occur in wild animals they are often caused by environmental variables that induce their own acclimation effects, making it difficult to discern if activity-sensitive feedback plays a role in ecological settings. We addressed this problem using a natural activity perturbation, where frogs hibernate in cold water, leaving brainstem motor circuits that generate breathing inactive for long periods. We show here that motor inactivity, amid complex environmental variables in the hibernation environment, represents a key signal for increasing AMPA-glutamate receptors (AMPARs) on motoneurons. Homeostatic upregulation of AMPARs do not regulate neural activity per se but instead correspond with enhanced evoked transmission selectively at cool temperatures. The results show how homeostatic synaptic plasticity may allow animals to restart motor behavior after chronic inactivity encountered in the natural environment. More broadly, these results introduce the concept of homeostatic plasticity as a mechanism to shape thermal tolerance ranges of neural performance in ecological settings.

neuroscience↗

bioRxiv2021

The mechanical and morphological properties of systemic and pulmonary arteries differ in the earth boa, a snake without ventricular pressure separation

The walls of the mammalian aorta and pulmonary artery are characterized by diverging morphologies and mechanical properties, which has been correlated with high systemic and low pulmonary blood pressures, as a result of intraventricular pressure separation in the mammalian ventricle. However, the relation between intraventricular pressure separation and diverging aortic and pulmonary artery wall morphologies and mechanical characteristics is not understood. The snake cardiovascular system poses a unique model for the study of this question, since representatives both with and without intraventricular pressure separation exist. In this study we perform uniaxial tensile testing on vessel samples taken from the aortas and pulmonary arteries of the earth boa, Acrantophis madagascariensis, a species without intraventricular pressure separation. We then compare these morphological and mechanical characteristics with samples from the ball python, Python regius, and the yellow anaconda, Eunectes notaeus, species with and without intraventricular pressure separation, respectively. Strikingly, we find that although the aortas and pulmonary arteries of A. madagascariensis respond similarly to the same intramural blood pressures, they diverge strongly in morphology, and that this is a common attribute among species without intraventricular pressure separation in this study. In contrast, P. regius aortas and pulmonary arteries diverge both morphologically and in terms of their mechanical properties. Altogether our data indicate that intraventricular pressure separation does not explain diverging aortic and pulmonary artery morphologies. Following the Law of Laplace, we propose that thin pulmonary arteries represent a mechanism to protect the fragile pulmonary vascular bed by reducing the blood volume that passes through, to which genetic factors may contribute more strongly than physiological parameters.

physiology↗