Castration attenuates prolactin response but potentiates ACTH response to conditioned stress in the rat

1995 ◽  
Vol 269 (4) ◽  
pp. R856-R863 ◽  
Author(s):  
E. W. Bingaman ◽  
L. D. Van de Kar ◽  
J. M. Yracheta ◽  
Q. Li ◽  
T. S. Gray
Keyword(s):  
Adrenocorticotropic Hormone ◽  
Behavioral Responses ◽  
Plasma Renin ◽  
Plasma Corticosterone ◽  
Sprague Dawley ◽  
Treatment Groups ◽  
Sprague Dawley Rats ◽  
Response To Stress ◽  
Prolactin Response ◽  
Psychological Stressor

The purpose of this study was to examine the effect of circulating androgens on neuroendocrine, autonomic, and behavioral responses to stress. The effects of conditioned stress were studied in male Sprague-Dawley rats that were intact, gonadectomized, or gonadectomized and treated with dihydrotestosterone (DHT). Intact animals received sham surgeries. Animals were stressed 3 wk after surgery. The adrenocorticotropic hormone (ACTH) response to conditioned stress was significantly potentiated (P < 0.01) in gonadectomized males compared with sham-operated and gonadectomized DHT-treated animals. In stressed rats, plasma corticosterone levels were significantly higher (P < 0.05) in gonadectomized animals compared with DHT-treated castrates. The prolactin response to stress was decreased (P < 0.01) in gonadectomized males compared with sham-operated and gonadectomized DHT-treated rats. The stress-induced increases in plasma renin activity and concentration were not altered in gonadectomized or in gonadectomized DHT-treated animals. Nonstressed DHT-treated castrates exhibited more “fearlike” behavior compared with nonstressed sham-operated and gonadectomized animals. However, conditioned stress produced the same behavioral effects in all treatment groups. The results demonstrate that the ACTH/corticosterone, prolactin, and behavioral responses to a psychological stressor are differentially regulated by circulating androgens.

scholarly journals Effects of repeated doses and continuous infusions of the growth hormone-releasing peptide hexarelin in conscious male rats

1998 ◽  
Vol 158 (3) ◽  
pp. 367-375 ◽  
Author(s):  
LK Conley ◽  
RC Gaillard ◽  
A Giustina ◽  
RS Brogan ◽  
WB Wehrenberg
Keyword(s):  
Adult Male ◽  
Plasma Corticosterone ◽  
Male Rats ◽  
Continuous Exposure ◽  
Sprague Dawley ◽  
Treatment Groups ◽  
Sprague Dawley Rats ◽  
Repeated Doses ◽  
The Mean ◽  
Plasma Gh

We have previously shown that hexarelin, a novel GH-releasing peptide (GHRP), is able to elicit GH release when administered i.v., s.c. or by mouth and that it is a more potent GH secretagogue than GHRP-6. In the current study, we investigated the effects of hexarelin administered as repeated doses at 2 h intervals or as a continuous 6, 30 or 174 h infusion to conscious male rats. In the first experiment, adult male Sprague-Dawley rats were prepared with dual indwelling jugular catheters. On the day of experimentation, these animals received three 25 micrograms/kg i.v. boluses of hexarelin at 2 h intervals with blood sampling at 5, 10, 15, 30, 60, 90 and 120 min after each dose. The mean peak GH response and the mean area under the GH response curve (AUC) for the 30 min after each administration were calculated and are reported as the mean +/- S.E.M. For both the peak and AUC results there was a significant (P < 0.05) difference in the GH response noted between the first (peak 301 +/- 37 ng/ml; AUC 5585 +/- 700 ng/ml per 30 min) and second (peak 149 +/- 47 ng/ml; AUC 3056 +/- 908 ng/ml per 30 min) injections of hexarelin, but not between the first and third (peak 214 +/- 49 ng/ml; AUC 3862 +/- 844 ng/ml per 30 min). In a second series of experiments, adult male Sprague-Dawley rats received continuous infusions (100 micrograms/h) of hexarelin or saline (1 ml/h) for 6, 30 or 174 h. Blood samples were collected every 20 min for the duration of the 6 h infusion and for the last 6 h of the two longer hexarelin infusions. Plasma GH concentrations peaked within 40 min of the initiation of infusion, but soon returned to basal levels. Mean plasma GH concentrations did not differ between any of the treatment groups, nor did any of the parameters of pulsatile hormone release analyzed. No significant differences in plasma corticosterone concentrations were noted between any of the treatment groups. On the other hand, while neither the 6 h (941 +/- 70 ng/ml) nor the 30 h (954 +/- 70 ng/ml) hexarelin infusions resulted in a significant increase in the plasma IGF-I concentrations over those noted in the saline controls (935 +/- 65 ng/ml), a 174 h hexarelin infusion did elicit a significant increase (1289 +/- 42 ng/ml; P < 0.05). Thus it appears that, while continuous exposure to hexarelin does not disrupt normal GH cycling, it may (after up to 174 h of exposure) alter other components of the growth axis. In addition, since the character of pulsatile GH release remained unaltered in response to the hexarelin infusion, it appears that this GHRP may not act by suppression of functional somatostatin tone as has been suggested previously.

scholarly journals Antidepressant-Like Effect of Lipid Extract ofChanna striatusin Postpartum Model of Depression in Rats

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Mohamed Saleem Abdul Shukkoor ◽  
Mohamad Taufik Hidayat Bin Baharuldin ◽  
Abdul Manan Mat Jais ◽  
Mohamad Aris Mohamad Moklas ◽  
Sharida Fakurazi ◽  
...  
Keyword(s):  
Postpartum Period ◽  
Estradiol Benzoate ◽  
Plasma Corticosterone ◽  
Positive Control ◽  
Lipid Extract ◽  
High Dose ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Malay Population ◽  
Swimming Test

Postpartum depression affects 15% of women.Channa striatus, a freshwater fish, is consumed in local Malay population as a rejuvenating diet during postpartum period. This study evaluated the antidepressant-like effect of lipid extract ofC. striatusfillet and its mechanism of action in female Sprague-Dawley rats in postpartum model of depression. The rats were ovariectomized and treated with high dose of progesterone and estradiol benzoate for 23 days to have hormone-simulated pregnancy. The day 24 and afterwards were considered as the postpartum period. During the postpartum period, lipid extract was administered at 125, 250, and 500 mg/kg through intraperitoneal route for 15 days. Fluoxetine (10 mg/kg) was used as the positive control. On postpartum day 15, the animals were tested in forced swimming test (FST) and open field test (OFT) followed by biochemical analysis. Withdrawal of hormone administration during the postpartum period induced depressive-like behavior in FST. Administration of lipid extract reversed that depressive-like behavior at 125, 250, and 500 mg/kg in FST. In OFT, it decreased the exploratory activity. The mechanism of the antidepressant-like effect may be mediated through the decrease in plasma corticosterone, increase in plasma oxytocin, and decrease in nuclear factor-kappa B in prefrontal cortex of rats.

scholarly journals Dexamethasone Suppressed LPS-Induced Matrix Metalloproteinase and Its Effect on Endothelial Glycocalyx Shedding

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Na Cui ◽  
Hao Wang ◽  
Yun Long ◽  
Longxiang Su ◽  
Dawei Liu
Keyword(s):  
Escherichia Coli ◽  
Vascular Endothelium ◽  
Free Water ◽  
Endothelial Glycocalyx ◽  
Sprague Dawley ◽  
Treatment Groups ◽  
Protein Levels ◽  
Sprague Dawley Rats ◽  
The Matrix ◽  
Rat Thoracic Aorta

The aim of this study is to determine the mechanism of sepsis-induced vascular hyperpermeability and the beneficial effect of glucocorticoid in protecting vascular endothelium. Male Sprague-Dawley rats were given either a bolus intraperitoneal injection of a nonlethal dose of LPS (Escherichia coli055:B5, 10 mg/kg, Sigma) or vehicle (pyrogen-free water). Animals of treatment groups were also given either dexamethasone (4 mg/kg, 30 min prior to LPS injection) or the matrix metalloproteinases (MMPs) inhibitor doxycycline (4 mg/kg, 30 min after LPS injection). Both activities and protein levels of MMP-2p<0.001and MMP-9p<0.001were significantly upregulated in aortic homogenates from LPS-treated rats, associated with decreased ZO-1p<0.001and syndecan-1p=0.011protein contents. Both dexamethasone and doxycycline could significantly inhibit MMPs activity and reserve the expressions of ZO-1 and syndecan-1. The inhibition of MMPs by dexamethasone was significantly lower than that by doxycycline, while the rescue of syndecan-1 expression from LPS-induced endotoxemic rat thoracic aorta was significantly higher in the dexamethasone-treated compared to the doxycycline-treatedp=0.03. In conclusion, activation of MMPs plays important role in regulating ZO-1 and syndecan-1 protein levels in LPS mediated endothelial perturbation. Both dexamethasone and doxycycline inhibit activation of MMPs that may contribute to the rescue of ZO-1 and syndecan-1 expression.

Importance of chloride for the correction of chronic metabolic alkalosis in the rat

1987 ◽  
Vol 253 (5) ◽  
pp. F1031-F1039 ◽  
Author(s):  
B. M. Wall ◽  
G. V. Byrum ◽  
J. H. Galla ◽  
R. G. Luke
Keyword(s):  
Plasma Volume ◽  
Metabolic Alkalosis ◽  
Choline Chloride ◽  
Plasma Renin ◽  
Sodium Balance ◽  
Sprague Dawley ◽  
Volume Contraction ◽  
Chloride Depletion ◽  
Sprague Dawley Rats ◽  
Sodium And Potassium

To determine whether chloride repletion without sodium could correct chronic chloride depletion metabolic alkalosis (CDA) in Sprague-Dawley rats without volume expansion and without increasing glomerular filtration rate (GFR), CDA was generated by peritoneal dialysis (PD) against 0.15 M NaHCO3 and maintained for 7-10 days by a chloride-restricted diet supplemented with sodium and potassium salts. Control animals were dialyzed against Ringer bicarbonate. The maintenance period of chronic CDA, compared with control, was characterized by hypokalemic metabolic alkalosis (serum TCO2 31.9 +/- 0.6 vs. 23.1 +/- 0.5 meq/l, P less than 0.05), volume contraction (plasma volume 3.76 +/- 0.08 vs. 4.19 +/- 0.22 ml/100 g body wt, P less than 0.05), decreased GFR (838 +/- 84 vs. 1045 +/- 45 microliters.min-1.100 g body wt-1, P less than 0.05), increased plasma renin activity (PRA) (63 +/- 13 vs. 12 +/- 3 ng.ml-1.h-1, P less than 0.05), but unchanged plasma aldosterone concentrations (PAC) (4.1 +/- 1.0 vs. 3.4 +/- 1.6 ng/dl, P = NS). Complete correction of chronic CDA was accomplished by 24 h of ingestion of choline chloride drink, and despite negative sodium balance, neutral potassium balance, continued bicarbonate ingestion, and persistent volume contraction (plasma volume 3.76 +/- 0.08 vs. 3.73 +/- 0.12 ml/100 g body wt pre- and postcorrection, P = NS), GFR remained decreased (659 +/- 87 vs. 1,045 +/- 45 microliters.min-1.100 g body wt-1, P less than 0.05), PRA decreased (63 +/- 13 vs. 33 +/- 5 ng.ml-1.h-1, P less than 0.05), but PAC did not change (4.1 +/- 1.0 vs. 6.1 +/- 1.6 ng/dl, P = NS) after correction of CDA.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Effects of Aqueous Quassia amara L. (Korales) Leaf Extract on the Cardiovascular and Respiratory Functions of Male Sprague-Dawley Rats

2018 ◽  
Vol 52 (6) ◽  
Author(s):  
Maria Concepcion C. Sison ◽  
Lynn Crisanta R. Panganiban ◽  
Daisy Mae A. Bagaoisan ◽  
Nelia P. Cortes-Maramba
Keyword(s):  
Blood Pressure ◽  
Adult Male ◽  
Leaf Extract ◽  
Sprague Dawley ◽  
Treatment Groups ◽  
Respiratory Flow ◽  
Sprague Dawley Rats ◽  
Parallel Group ◽  
Aqueous Leaf Extract ◽  
Quassia Amara

Objective. To To evaluate potential effects of the aqueous extract of Quassia amara L. leaves on the cardiovascular and respiratory systems of adult male Sprague- Dawley rats. Methods. The cardiovascular and respiratory effects of the Quassia amara L. leaf extract on adult male SpragueDawley rats were assessed using non-invasive blood pressure (NIBP) determination and head-out plethysmography, respectively, in a randomized, parallel group study. Mean observations of blood pressure and heart rate were recorded at different time periods after dosing. Respiratory flow and irritation effects were evaluated using mean observations of respiratory rate (RR), tidal volume (TV), mid-expiratory flow rate (EF50), time of inspiration (TI) and expiration (TE), and time of break (TB) and pause (TP). Results. There were no significant differences among the control and the treatment groups in SBP, DBP and HR parameters. The extract showed statistically significant effect on mean RR by time period (F=2.45, p=0.0234), trends over time of TV among the dose groups (F=2.00, p=0.0202), and EF50 among dose groups ((F=3.11, p=0.0422). However, these did not correlate with the changes in the time of break (TB) and time of pause (TP) which are more sensitive and specific tests for respiratory irritation. Conclusion. Aqueous leaf extract of Quassia appeared to have no significant effects on SBP, DPB, Pulse pressure, and HR. There are no conclusive dose-related respiratory flow or pulmonary irritation effects.

Effects of prior adrenalectomy on postpneumonectomy lung growth in the rat

1985 ◽  
Vol 248 (1) ◽  
pp. E70-E74 ◽  
Author(s):  
R. A. Bennett ◽  
P. C. Colony ◽  
J. L. Addison ◽  
D. E. Rannels
Keyword(s):  
Dry Mass ◽  
Hydrocortisone Acetate ◽  
Lung Growth ◽  
Sprague Dawley ◽  
Treatment Groups ◽  
Compensatory Lung Growth ◽  
Sprague Dawley Rats ◽  
Total Dna ◽  
Glucocorticoid Replacement Therapy ◽  
The Right

The effects of adrenalectomy, with and without subsequent glucocorticoid replacement therapy, on postpneumonectomy compensatory lung growth in the rat were investigated. Male Sprague-Dawley rats (200-230 g) were subjected to no operation (UNOP), left pneumonectomy (PNX), or PNX preceded by bilateral adrenalectomy 5 days earlier (ADX/PNX). At 14 days post-PNX, when compensatory lung growth is normally complete in 200-g rats, right lung (RL) dry weights of PNX (263 +/- 6 mg, n = 26) and ADX/PNX (334 +/- 13 mg, n = 25) rats were increased 58 and 101%, respectively, relative to UNOP controls (166 +/- 5 mg, n = 10). Increases in total DNA, RNA, and protein in the right lungs of PNX and ADX/PNX rats occurred in proportion to RL dry mass. The increase in all parameters examined in PNX and ADX/PNX rats at 7 days post-PNX was half that at 14 days, indicating linear lung growth in both treatment groups. The stimulatory effect of ADX on lung growth was blocked by hydrocortisone acetate (HCA), administered intraperitoneally in daily doses of 5 mg/kg, beginning on the day of PNX. The RL dry weights of HCA-treated ADX/PNX rats (241 +/- 7 mg, n = 10) did not differ significantly from the corresponding value in PNX rats (270 +/- 14 mg, n = 7). The lower RL weights in the HCA-treated rats resulted from an inhibition of cell division, as evidenced by the total RL DNA content, which was similar to that in PNX animals.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Aversion to Desflurane and Isoflurane in Sprague-Dawley Rats (Rattus norvegicus)

Animals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 950 ◽  
Author(s):  
Katrina Frost ◽  
Maaria Shah ◽  
Vivian S.Y. Leung ◽  
Daniel S.J. Pang
Keyword(s):  
Carbon Dioxide ◽  
Exposure Time ◽  
Washout Period ◽  
Rattus Norvegicus ◽  
Sprague Dawley ◽  
Initial Exposure ◽  
Treatment Groups ◽  
Avoidance Paradigm ◽  
Sprague Dawley Rats

Carbon dioxide and isoflurane are widely used for killing rats, yet may not truly achieve “euthanasia”, because they elicit aversion. The inhalant anesthetic desflurane is faster acting than isoflurane, representing a potential refinement. Using an aversion-avoidance paradigm, 24 rats were exposed to isoflurane or desflurane (n = 12 per group) at initial exposure. Fourteen rats were then re-exposed to isoflurane or desflurane (n = 7 per group), after a 7 days washout period. Initial exposure: time to recumbency was faster for desflurane than isoflurane (p = 0.0008, 95% CI [-12.9 to 32.6 s]), with 9/12 and 6/12 rats becoming recumbent, respectively. At initial exposure, there was no difference between groups in time to withdrawal (p = 0.714). At re-exposure, all rats withdrew and no rats became recumbent. Time to withdrawal at re-exposure did not differ between treatment groups (p = 0.083). Compared to initial exposure, time to withdrawal during re-exposure was similar for isoflurane (p = 0.228) and faster with desflurane (p = 0.012, 95% CI [19.1 to 49.5 s]). Isoflurane and desflurane are similarly aversive, with aversion increasing at re-exposure. The shorter time from exposure to recumbency with desflurane indicates that any distress is of a shorter duration when compared with isoflurane.

Lactation alters the effects of conditioned stress on immune function

1997 ◽  
Vol 272 (1) ◽  
pp. R16-R25 ◽  
Author(s):  
N. Shanks ◽  
A. Kusnecov ◽  
M. Pezzone ◽  
J. Berkun ◽  
B. S. Rabin
Keyword(s):  
Immune Function ◽  
Stress Responses ◽  
Lymphocyte Proliferation ◽  
Physiological State ◽  
Cell Receptor ◽  
Plasma Corticosterone ◽  
Endocrine Function ◽  
Nitrite Accumulation ◽  
Sprague Dawley ◽  
Sprague Dawley Rats

During lactation, endocrine function is altered and stress responses are dampened. Stress effects on immune function are partially determined by endocrine factors; therefore, we assessed whether stress similarly alters immune function during lactation. Sprague-Dawley rats were conditioned by exposure to a tone paired with foot shock (2 sessions, 16 shocks each) prior to breeding or were left undisturbed. Lactating (day 10) (Lac) and nonlactating diestrous virgin controls (C) were killed immediately after reexposure to the tone or removal from their home cage. Plasma corticosterone stress responses were dampened in Lac relative to C animals. Peripheral blood lymphocyte proliferation to T cell receptor antibody stimulation was reduced to a similar extent in both experimental groups. Conditioned stress reduced splenocyte proliferation and increased nitrite accumulation in C animals, but not in Lac animals. Mesenteric lymph node lymphocyte proliferation was significantly increased after stress in Lac compared with C animals. Both plasma interleukin-6 (IL-6) and phytohemagglutinin-stimulated splenic IL-6 production were increased in Lac animals compared with C animals after stress exposure. These data indicate that stress-induced alterations may be determined by different regulatory mechanisms within immune compartments and that these effects depend on the physiological state of the organism.

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