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Anaesthetised Rats (anaesthetised + rat)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Angiotensin AT1 Receptor Antagonist Losartan and the Defence Reaction in the Anaesthetised Rat.

EXPERIMENTAL PHYSIOLOGY, Issue 3 2003
Effect on the Carotid Chemoreflex
Modulation at the level of the nucleus tractus solitarii (NTS) appears to be an effective way of controlling cardiovascular reflexes. Angiotensin II acting on angiotensin AT1 receptors at the central nervous system appears to have an important role in these modulatory processes. The hypothalamic defence area (HDA) is a potential source of descending fibres containing angiotensin II that innervate the NTS. We investigated the effect of AT1 receptor blockade in the NTS on the response to stimulation of HDA in anaesthetised rats treated with the neuromuscular blocking agent pancuronium bromide. The characteristic increase in heart rate, blood pressure and phrenic nerve activity evoked by electrical stimulation of HDA is decreased by the microinjection of the AT1 receptor antagonist losartan into the NTS and the cardiovascular response to carotid body chemical stimulation is also reduced. These results support the hypothesis that AT1 receptors in the NTS play a role in the modulation of cardiovascular reflexes, and modify the influence exerted on the processing of these reflexes by other areas of the central nervous system. [source]

Constitutive Secretion of Immunoglobulin a and Other Proteins into Lumina of Unstimulated Submandibular Glands in Anaesthetised Rats

EXPERIMENTAL PHYSIOLOGY, Issue 1 2003
G. B. Proctor
Salivary fluid secretion is dependent upon reflex stimuli mediated by autonomic nerves. In order to determine if immunoglobulin A (IgA) and salivary proteins are secreted in the absence of nerve stimulation, small volumes (< 2 µl) of saliva were consecutively collected from the submandibular duct of anaesthetised rats following rest pauses in order to sample the protein contents of the ductal system. Within the first 5 µl of such saliva collected by parasympathetic nerve stimulation, IgA and other salivary proteins reached peak concentrations that were over 20-fold greater than levels in parasympathetically stimulated saliva subsequently collected during a 5 min period of stimulation. Confocal microscopy of TRITC-labelled IgA added to live, acutely isolated submandibular acini indicated that it did not enter the lumina by paracellular leakage. IgG is thought to enter saliva by paracellular leakage but did not accumulate in luminal saliva in the present study. Electrophoresis suggested that the major proteins secreted in the absence of stimulation were the same as those present in subsequently stimulated saliva. It can be concluded that IgA and other major submandibular proteins are secreted into glandular lumina in the absence of nerve stimulation. The functional significance of such unstimulated protein secretion is at present unclear. [source]

Effect of mesenchymal stem cell penile transplantation on erectile signaling of aged rats

ANDROLOGIA, Issue 3 2010
M. T. Abdel Aziz
Summary Stem cell-based therapy targeted at the penile tissue has been lately considered in preclinical studies. This work aimed to assess the effect of intracavernous administration of mesenchymal stem cells (MSCs) in aged rats (n = 100). They were subjected to single intracavernous injection (ICI) of 1.0 million MSCs, followed up for 3, 4 weeks, 3 and 4 months (each group 25 rats) and compared with both adult and aged controls (n = 50). In dissected cavernous tissues, cGMP and histopathology were assessed in addition to intracavernous pressure (ICP) measurement in some anaesthetised rats. The results showed that cavernous tissue cGMP was significantly increased in MSCs transplanted rats in all investigated groups compared with the controls. The mean cavernous cGMP levels after 3 and 4 months of MSCs transplantation were significantly increased compared with those after 3 or 4 weeks. Cavernous tissue ICP measurement showed significant increase in MSCs transplanted groups compared with the controls, more in the long-term follow up than in the shorter one. Histopathological examination detected markedly dilated sinusoidal vascular spaces in the long-term follow-up study. It is concluded that stem cell-based therapy is feasible for age-associated erectile dysfunction and could improve erectile signaling. [source]

Cannabinoid receptor activation in the rostral ventrolateral medulla oblongata evokes cardiorespiratory effects in anaesthetised rats

BRITISH JOURNAL OF PHARMACOLOGY, Issue 2 2003
James R Padley
The nature of the cardiorespiratory effects mediated by cannabinoids in the hindbrain is poorly understood. In the present study we investigated whether cannabinoid receptor activation in the rostral ventrolateral medulla oblongata (RVLM) affects cardiovascular and/or respiratory function. Initially, we looked for evidence of CB1 receptor gene expression in rostral and caudal sections of the rat ventrolateral medulla (VLM) using reverse transcription,polymerase chain reaction. Second, the potent cannabinoid receptor agonists WIN55,212-2 (0.05, 0.5 or 5 pmol per 50 nl) and HU-210 (0.5 pmol per 50 nl) or the CB1 receptor antagonist/inverse agonist AM281 (1 pmol per 100 nl) were microinjected into the RVLM of urethane-anaesthetised, immobilised and mechanically ventilated male Sprague,Dawley rats (n=22). Changes in splanchnic nerve activity (sSNA), phrenic nerve activity (PNA), mean arterial pressure (MAP) and heart rate (HR) in response to cannabinoid administration were recorded. The CB1 receptor gene was expressed throughout the VLM. Unilateral microinjection of WIN55,212-2 into the RVLM evoked short-latency, dose-dependent increases in sSNA (0.5 pmol; 175±8%, n=5) and MAP (0.5 pmol; 26±3%, n=8) and abolished PNA (0.5 pmol; duration of apnoea: 5.4±0.4 s, n=8), with little change in HR (P<0.005). HU-210, structurally related to ,9 -tetrahydrocannabinol (THC), evoked similar effects when microinjected into the RVLM (n=4). Surprisingly, prior microinjection of AM281 produced agonist-like effects, as well as significantly attenuated the response to subsequent injection of WIN55,212-2 (0.5 pmol, n=4). The present study reveals CB1 receptor gene expression in the rat VLM and demonstrates sympathoexcitation, hypertension and respiratory inhibition in response to RVLM-administered cannabinoids. These findings suggest a novel link between CB1 receptors in this region of the hindbrain and the central cardiorespiratory effects of cannabinoids. The extent to which these central effects contribute to the cardiovascular and respiratory outcomes of cannabis use remains to be investigated. British Journal of Pharmacology (2003) 140, 384,394. doi:10.1038/sj.bjp.0705422 [source]