The pre-Bötzinger complex participates in generating the respiratory effects of thyroliberin

Abstract

Experiments on anesthetized rats were performed to study the effects of microinjection of thyroliberin (10 fM-100 microM) into the area of the pre-Bötzinger complex on respiratory and circulatory parameters. Thyroliberin dose-dependently increased respiration frequency, with shortening of inspiration and expiration. Tidal volume and the amplitude of the integrated EMG recorded from the inspiratory muscles decreased after administration of concentrated solutions. Using this dosage method, thyroliberin had weak effects on systemic hemodynamics. The data suggest that structures located in the area of the pre-Bötzinger complex take part in generating the respiratory effects of thyroliberin.

Intravenous and Intratracheal Thyrotropin Releasing Hormone and Its Analog Taltirelin Reverse Opioid-Induced Respiratory Depression in Isoflurane Anesthetized Rats

“…TRH and its analogs activate breathing in a number of species including humans and nonhuman primates (Kraemer et al, 1976;Nink et al, 1991). Breathing effects are likely central in origin, since small TRH doses injected into cerebral ventricles or near the respiratory rhythm-generating pre-Bötzinger complex provoke tachypnea (Hedner et al, 1983;Inyushkin et al, 1999). Additionally, TRH directly activates medullary chemosensing, nucleus tractus solitarius, and hypoglossal motor neurons, and taltirelin restores central carbon dioxide chemosensing in Brown Norway rats (Dekin et al, 1985;Bayliss et al, 1992;Mulkey et al, 2007;Puissant et al, 2015).…”

Are thyrotropin‐releasing hormone (TRH) and analog taltirelin viable reversal agents of opioid‐induced respiratory depression?

“…Apart from areas within the brainstem respiratory network, TRH and its receptors were identified in the phrenic motor nucleus and hypoglossal motoneurons 22,32 . Later studies demonstrate that TRH exerts its effects through actions within the preBötzinger complex at TRH‐receptors, 15,33‐37 although similar excitatory effects were observed from TRH injections at other nuclei involved in ventilatory control such as the dorsal respiratory group, area postrema, nucleus ambiguous, nucleus tractus solitarius, and retrotrapezoid nucleus, 38‐43 Still, also respiratory depression was observed after injection of TRH into the Bötzinger complex of the anesthetized rabbit 43 . Finally, TRH analogue taltirelin restored the central ventilatory chemoreflex in rats with an inherent ventilatory insensitivity to hypercapnia 44 …”