Central mechanism underlying pressor and bradycardic effect of intracerebroventricularly injected arachidonic acid

2011 ◽  
Vol 89 (2) ◽  
pp. 127-133 ◽  
Author(s):  
Murat Yalcin
Keyword(s):  
Heart Rate ◽  
Arachidonic Acid ◽  
Cardiovascular Effect ◽  
Cardiovascular Effects ◽  
Central Mechanism ◽  
Sprague Dawley ◽  
Synthesis Inhibitor ◽  
Sprague Dawley Rats ◽  
Cox Inhibitor ◽  
Different Doses

The aim of the current study was to determine the central cyclooxygenase (COX) pathway and central thromboxane signaling in the cardiovascular effects evoked by arachidonic acid (AA). As a main control for the study, different doses of AA (75, 150, or 300 µg) were administered intracerebroventricularly (i.c.v.). Centrally injected AA dose- and time-dependently increased mean arterial pressure and decreased heart rate in conscious normotensive Sprague–Dawley rats. The maximal cardiovascular effects of AA were observed at min 10 of the injection and lasted almost 30 min. To investigate the central mechanism of the AA-induced cardiovascular effect in conscious normotensive animals, pretreatment with nonselective COX inhibitor indomethacin (200 µg; i.c.v.), thromboxane A2 (TXA2) synthesis inhibitor furegrelate (250 or 500 µg; i.c.v.), or TXA2 receptor antagonist SQ-29548 (8 or 16 µg; i.c.v.) was carried out 15 min before AA (150 µg; i.c.v.) injection. While indomethacin completely prevented the pressor and bradycardic responses to AA, furegrelate and SQ-29548 attenuated these effects in part in awake normotensive rats. In conclusion, these findings suggest that the pressor and bradycardic cardiovascular effects of centrally injected AA are dependent on COX activity being totally central and the TXA2 signaling pathway being subsequently central, at least in part.

scholarly journals The Intermediation Role of Central Cyclooxygenase Products TXA2, PGF2α, PGE, and PGD in Orexin-evoked Cardiovascular Effects

2021 ◽  
Author(s):  
Burçin Altınbaş ◽  
Gökcen Guvenc Bayram ◽  
Murat Yalcin
Keyword(s):  
Receptor Antagonist ◽  
Cardiovascular Effects ◽  
Cardiovascular Responses ◽  
Mediating Effects ◽  
Sprague Dawley ◽  
Synthesis Inhibitor ◽  
Sprague Dawley Rats ◽  
Arachidonic Acid Metabolites ◽  
Acid Metabolites

Abstract Centrally injected some prostaglandins (PG) and orexin (OX) produce similar cardiovascular responses. We have recently reported that both central cyclooxygenase (COX) and central lipoxygenase (LOX) enzymes mediate the cardiovascular effects of OX. In the current study, we aimed to investigate the mediating effects of thromboxane (TX) A2, PGD, PGE, and PGF2a, as COX pathway subproducts known to be active in cardiovascular control, on cardiovascular responses elicited by OX. Intracerebroventricular (i.c.v.) injection of OX increased cardiovascular levels in normotensive male Sprague Dawley rats. Moreover, central pretreatment with the TXA2 synthesis inhibitor furegrelate, PGF2α receptor antagonist, PGF2α-dimethylamine, PGE, and PGD receptor antagonist AH6809 partially attenuated the centrally administered OX -induced pressor and tachycardic cardiovascular responses in rats. In conclusion, our results show that i.c.v. injection of OX increases blood pressure and heart rate. Moreover, TXA2, PGF2α, PGE, and PGD mediate, at least in part, the centrally applied OX -evoked pressor and tachycardic responses. The results suggest that centrally injected OX -evoked pressor and tachycardia responses may also be mediated by arachidonic acid metabolites other than TXA2, PGF2α, PGE, and PGD.

Neuropeptide action in nucleus tractus solitarius: angiotensin specificity and hypertensive rats

1985 ◽  
Vol 249 (3) ◽  
pp. R341-R347 ◽  
Author(s):  
R. Casto ◽  
M. I. Phillips
Keyword(s):  
Heart Rate ◽  
Nucleus Tractus Solitarius ◽  
Dose Range ◽  
Cardiovascular Effects ◽  
Ang Ii ◽  
Sprague Dawley ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Sprague Dawley Rats ◽  
Wistar Kyoto

We have reported that microinjection of angiotensin II (ANG II) into the nucleus tractus solitarius of urethan-anesthetized normotensive rats produces an increase in mean arterial pressure (MAP) over the dose range 50-500 pmol. The effect in spontaneously hypertensive rats (SHR) is now reported. Over the range 100-500 pmol SHR exhibit increases in MAP and heart rate greater than Wistar-Kyoto or Sprague-Dawley rats. SHR did not exhibit exaggerated responses to intravenous phenylephrine, suggesting a central site of increased responsiveness to ANG II. We also found depressor effects in Sprague-Dawley at lower doses (0.1 and 1 pmol). The decreases in MAP were extremely variable and not dose related. A selected dose of additional neuropeptides identified in the NTS was tested. Somatostatin, bradykinin, and vasoactive intestinal peptide (0.5 nmol) were without cardiovascular effects. Oxytocin and vasopressin, however, produced significant increases in MAP. Substance P produced a very small but significant increase in heart rate and MAP. Interaction between the vasopressin and ANG II pressor effects was studied, and each proved to be independent.

Serotonin depletion reduces both acquisition and expression of context-conditioned fear

2021 ◽  
pp. 1-8
Author(s):  
S. Melker Hagsäter ◽  
Robert Pettersson ◽  
Axel Holmäng ◽  
Elias Eriksson
Keyword(s):  
Unconditioned Stimulus ◽  
Memory Consolidation ◽  
Clinical Studies ◽  
Conditioned Fear ◽  
Sprague Dawley ◽  
Serotonin Synthesis ◽  
Synthesis Inhibitor ◽  
Serotonin Depletion ◽  
Sprague Dawley Rats ◽  
The Impact

Abstract Objective: Whereas numerous experimental and clinical studies suggest a complex involvement of serotonin in the regulation of anxiety, it remains to be clarified if the dominating impact of this transmitter is best described as anxiety-reducing or anxiety-promoting. The aim of this study was to assess the impact of serotonin depletion on acquisition, consolidation, and expression of conditioned fear. Methods: Male Sprague–Dawley rats were exposed to foot shocks as unconditioned stimulus and assessed with respect to freezing behaviour when re-subjected to context. Serotonin depletion was achieved by administration of a serotonin synthesis inhibitor, para-chlorophenylalanine (PCPA) (300 mg/kg daily × 3), (i) throughout the period from (and including) acquisition to (and including) expression, (ii) during acquisition but not expression, (iii) after acquisition only, and (iv) during expression only. Results: The time spent freezing was significantly reduced in animals that were serotonin-depleted during the entire period from (and including) acquisition to (and including) expression, as well as in those being serotonin-depleted during either acquisition only or expression only. In contrast, PCPA administrated immediately after acquisition, that is during memory consolidation, did not impact the expression of conditioned fear. Conclusion: Intact serotonergic neurotransmission is important for both acquisition and expression of context-conditioned fear.

Contribution of α2-adrenoceptors in caudal ventrolateral medulla to cardiovascular regulation in rat

1998 ◽  
Vol 274 (4) ◽  
pp. R1119-R1124 ◽  
Author(s):  
Shogo Sesoko ◽  
Hiromi Muratani ◽  
Masanobu Yamazato ◽  
Hiroshi Teruya ◽  
Shuichi Takishita ◽  
...  
Keyword(s):  
Cardiovascular Effect ◽  
Ventrolateral Medulla ◽  
Sprague Dawley ◽  
Renal Sympathetic Nerve Activity ◽  
Caudal Ventrolateral Medulla ◽  
Adrenoceptor Antagonist ◽  
Sprague Dawley Rats ◽  
Artificial Cerebrospinal Fluid ◽  
Cardiovascular Neurons ◽  
Selective Blocker

The inhibitory action of α2-agonists on the cardiovascular neurons has been elucidated in the rostral ventrolateral medulla (RVLM) but not in the caudal ventrolateral medulla (CVLM). Our study aimed to clarify whether microinjection of clonidine into the CVLM elicits any cardiovascular effect and whether endogenous α2-adrenoceptor-mediated mechanisms contribute to the tonic activity of the CVLM neurons. In male Sprague-Dawley rats (7–9 wk old, 270–320 g) anesthetized with urethan, unilateral microinjection of 8 nmol of clonidine into the CVLM ( n = 10) increased mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) by 12.1 ± 1.8 mmHg (mean ± SE, P < 0.01) and 25.8 ± 4.8% ( P < 0.01), while heart rate (HR) remained unaltered. Unilateral microinjection of 2 nmol of SKF-86466, a selective blocker of the α2-adrenoceptors, into the CVLM ( n = 10) decreased MAP, HR, and RSNA (−11.6 ± 2.6 mmHg, −26 ± 7 beats/min, and −15.3 ± 1.7%, respectively, P < 0.01 for each). Artificial cerebrospinal fluid caused neither a cardiovascular effect nor a sympathetic response. Prior injection of SKF-86466 into the ipsilateral CVLM attenuated the effects of clonidine. Bilateral microinjection of muscimol into the RVLM abolished the effects of both clonidine and SKF-86466 injected into the CVLM. The pressor and sympathoexcitatory effects of clonidine injected into the CVLM suggest a neuroinhibitory action of the drug on the CVLM neurons. In addition,the depressor and sympathoinhibitory effects of SKF-86466 injected into the CVLM indicated that activation of α2-adrenoceptors by endogenous ligand inhibits CVLM neurons. The effects of clonidine and the α2-adrenoceptor antagonist in the CVLM require the integrity of the RVLM.

Androgen-mediated sex differences of cardiovascular responses in rats

1978 ◽  
Vol 235 (2) ◽  
pp. H242-H246 ◽  
Author(s):  
P. J. Baker ◽  
E. R. Ramey ◽  
P. W. Ramwell
Keyword(s):  
Sex Differences ◽  
Arachidonic Acid ◽  
Rank Order ◽  
Cardiovascular Responses ◽  
Sprague Dawley ◽  
Similar Treatment ◽  
Depressor Response ◽  
Sprague Dawley Rats ◽  
Significant Change ◽  
Dose Levels

Sex differences in the systemic depressor response to arachidonic acid (50 or 150 microgram/kg iv) were observed in intact and castrated anesthetized Sprague-Dawley rats. The rank order of responsiveness was: castrate males, castrate females, females, males; all four groups were significantly different (P less than 0.05) at the higher dose. Castrated males pretreated with testosterone (1 mg/kg sc) 5 or 7 days previously gave a response at the higher arachidonate dose levels that was of the same order as that obtained with intact males. Similar treatment of castrate males with androgen potentiated (P less than 0.05) the vasopressor action of norepinephrine (0.25 microgram/kg) on day 7 after the testosterone pretreatment. In contrast, treatment with depot estradiol (100 microgram/kg sc) in castrate males produced no significant change in the response to either of the vasoactive compounds on both days 5 and 7 after pretreatment. These data suggest that testosterone may be a significant factor in the development of sex differences in the cardiovascular systems of rats.

Cinnamomum cassia ameliorates Ni-NPs-induced liver and kidney damage in male Sprague Dawley rats

2020 ◽  
Vol 39 (11) ◽  
pp. 1565-1581
Author(s):  
S Iqbal ◽  
F Jabeen ◽  
C Peng ◽  
MU Ijaz ◽  
AS Chaudhry
Keyword(s):  
Dependent Manner ◽  
Sprague Dawley ◽  
Cinnamomum Cassia ◽  
Preliminary Information ◽  
Sprague Dawley Rats ◽  
Liver And Kidney ◽  
Altered Blood ◽  
Biochemical Analyses ◽  
Dose Dependent ◽  
Different Doses

Nickel nanoparticles (Ni-NPs) have been widely used in various industries related to electronics, ceramics, textiles, and nanomedicine. Ambient and occupational exposure to Ni-NPs may bring about potential detrimental effects on animals and humans. Thus, there is a growing effort to identify compounds that can ameliorate NPs-associated pathophysiologies. The present study examined Cinnamomum cassia ( C. cassia) bark extracts (CMBE) for its ameliorative activity against Ni-NPs-induced pathophysiological and histopathological alterations in male Sprague Dawley rats. The biochemical analyses revealed that dosing rats with Ni-NPs at 10 mg/kg/body weight (b.w.) significantly altered the normal structural and biochemical adaptations in the liver and kidney. Conversely, supplementations with CMBE at different doses (225, 200, and 175 mg/kg/b.w. of rat) ameliorated the altered blood biochemistry and reduced the biomarkers of liver and kidney function considerably ( p < 0.05) in a dose-dependent manner. However, the best results were at 225 mg/kg/b.w. of rat. The study provided preliminary information about the protective effect of C. cassia against Ni-NPs indicated liver and kidney damages. Future investigations are needed to explore C. cassia mechanism of action and isolation of single constituents of C. cassia to assess their pharmaceutical importance accordingly.

Impaired follicular development and endocrine disorders in female rats by prepubertal exposure to toxic doses of cadmium

2020 ◽  
Vol 36 (2) ◽  
pp. 63-75
Author(s):  
Saman Saedi ◽  
Mohammad Reza Jafarzadeh Shirazi ◽  
Mohammad Javad Zamiri ◽  
Mehdi Totonchi ◽  
Mohammad Dadpasand ◽  
...  
Keyword(s):  
Steroid Hormones ◽  
Endocrine System ◽  
Follicular Development ◽  
Female Rats ◽  
High Dose ◽  
Endocrine Disorders ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Puberty Onset ◽  
Different Doses

Cadmium (Cd) has been associated with several physiological problems including reproductive and endocrine system dysfunction resulting in temporary infertility. The principal objective of this project was to investigate the effects of prepubertal exposure to toxic doses of Cd on puberty onset, the endocrine system, and follicular development. For this purpose, 16 female Sprague-Dawley rats weaned on postnatal day (PND) 21 were randomly divided into 4 groups ( n = 4 per group). The treatments were as follows: 0, 25, 50, and 75 mg/kg/day of cadmium chloride (CdCl2) by oral gavage from PND 21 to observation of first vaginal opening (VO). The results demonstrated that prepubertal exposure to different doses of CdCl2 delays the age of VO, first diestrus, and first proestrus via altering the concentrations of estradiol and progesterone. The low level of these steroid hormones contributed to lower differentiation and maturation of follicles and it finally led to reduced ovarian reservoir of follicles and impaired follicular development. The number of atretic follicles and secondary follicles with premature cavity increased in rats that received a high dose of CdCl2, whereas the number of secondary follicles and corpora luteum decreased in the same circumstances. Taken together, these data suggest that prepubertal exposure to toxic doses of Cd delays the onset of puberty via disorderliness in the concentration of steroid hormones and reduces the ovarian reservoir of follicles, as well as folliculogenesis.

scholarly journals Effects of Interferon-Gamma on Bone Remodeling during Experimental Tooth Movement

2007 ◽  
Vol 77 (1) ◽  
pp. 135-141 ◽  
Author(s):  
Sila Mermut ◽  
Ali Osman Bengi ◽  
Erol Akin ◽  
Mehmet Kürkçü ◽  
Şeniz Karaçay
Keyword(s):  
Trabecular Bone ◽  
Bone Remodeling ◽  
Interferon Gamma ◽  
Tooth Movement ◽  
Orthodontic Tooth Movement ◽  
Bone Area ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Ifn Γ ◽  
Different Doses

Abstract Objective: To determine the effects of interferon-gamma (IFN-γ) on bone remodeling during orthodontic tooth movement. Materials and Methods: Thirty adult male Sprague Dawley rats were randomly categorized into five groups. IFN-γ was administered in three different doses (0.01, 0.02, and 0.05 μg/20 μL) and the remaining two groups served as control. Mandibular first molars were moved mesially by means of Ni-Ti closed coil springs in all groups. The results were evaluated histomorphometrically, and parameters of trabecular bone volume (BV/TV), trabecular bone number (Tr.N), and trabecular separation (Tr.Sep) were observed at the interradicular bone area of the mandibular first molars. Results: Increases in BV/TV and Tr.N and decreases in Tr.Sep revealed the antiosteoclastic activity of IFN-γ. Conclusion: IFN-γ administration may be useful clinically for anchorage control.

A STANDARDIZED METHOD FOR THE PRODUCTION OF HEMORRHAGIC SHOCK IN THE RAT

1955 ◽  
Vol 33 (3) ◽  
pp. 436-447 ◽  
Author(s):  
H. G. Downie ◽  
J. A. F. Stevenson
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Mortality Rate ◽  
Hemorrhagic Shock ◽  
Respiratory Rate ◽  
Rectal Temperature ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Standardized Method

Although the blood pressure is one of the important criteria in the standardization of hemorrhagic shock in the dog, it has rarely been used for this purpose in the rat. A method resembling the reservoir technique developed by Wiggers and Werle (1942) for the dog using blood pressure as the criterion has been modified for use with the rat. Male Sprague-Dawley rats weighing approximately 400 gm. were used. In the standardization of this technique the blood pressure was reduced to 30 mm. Hg in a 10-min. period of hemorrhage and then maintained at this level by subsequent small hemorrhages into the reservoir until reinfusion indicated the beginning of vascular collapse, at which time all the blood in the reservoir was returned. Considering that those animals which lived longer than 48 hr. were survivors, in a series of 27 animals, 21 died and 6 survived—a mortality rate of 78%.During the hypotensive period there was a consistent and steady drop in the respiratory rate and rectal temperature. The heart rate declined initially and tended to recover as the hypotensive period progressed. After reinfusion the blood pressure rose but. did not reach prehemorrhage levels. Hemorrhage into the bowel and convulsions were significant postreinfusion findings.

Sign in / Sign up

Export Citation Format

Share Document