Daily spontaneous running alters behavioral and neurochemical indexes of nigrostriatal function.
Animal/*physiology; Animals; Behavior; Chromatography; Circadian Rhythm; Corpus Striatum/cytology/*physiology; Dopamine/*metabolism; High Pressure Liquid; In Vitro Techniques; Male; Neuropsychological Tests; Organ Size; Perfusion; Physical Conditioning; Potassium/*metabolism; Psychomotor Performance/*physiology; Random Allocation; Rats; Sprague-Dawley
Behavioral and neurochemical indexes of nigrostriatal dopaminergic function were compared between sedentary control rats (n = 12) and daily spontaneous running (DSR) male rats (n = 10). Nine weeks of DSR did not significantly alter body, heart, pituitary, or testes weights. DSR and control animals did differ in performance on a sensorimotor beam walking task, with DSR rats showing significantly shorter times required to cross the beam (60 +/- 17 vs. 119 +/- 14s; P \textless 0.02) as well as fewer slips off the beam (3.0 +/- 0.8 vs 6.2 +/- 1.1; P \textless 0.05). DSR animals also engaged in significantly greater durations of social investigation than control rats (43 +/- 5 vs 25 +/- 3 s; P \textless 0.01) when tested in a social investigation memory-recognition test. Basal dopamine release rates from superfused corpus striatal tissue fragments of DSR rats were about one-half those obtained from control animals (18 +/- 5 vs. 34 +/- 6 pg.mg-1.min-1; P \textless 0.05), whereas responses of these striatal tissue fragments to a depolarizing concentration of potassium were virtually identical (45 +/- 10 vs. 47 +/- 8 pg.mg-1.min-1). These data indicate that a relatively limited intensity of DSR insufficient to alter cardiovascular function can exert substantial effects on behavioral and neurochemical indicators of nigrostriatal dopaminergic activity.
Dluzen D E; Liu B; Chen C Y; DiCarlo S E
Journal of applied physiology (Bethesda, Md. : 1985)
1995
1995-04
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1152/jappl.1995.78.4.1219" target="_blank" rel="noreferrer noopener">10.1152/jappl.1995.78.4.1219</a>
Daily exercise attenuates the sympathetic component of the arterial baroreflex control of heart rate.
Animal/*physiology; Animals; Arteries/drug effects/innervation/*physiology; Baroreflex/drug effects/*physiology; Body Weight; Female; Heart Rate/*physiology; Heart/anatomy & histology/*physiology; Nitroprusside/pharmacology; Organ Size; Parasympathetic Nervous System/physiology; Phenylephrine/pharmacology; Physical Conditioning; Pulse; Rats; Sympathetic Nervous System/physiology
The influence of daily spontaneous running (DSR) on the sympathetic (SC) and parasympathetic components of the arterial baroreflex control of heart rate (HR) was examined in 16 female Long Evans rats [8 sedentary (SED) and 8 DSR]. After
Collins H L; DiCarlo S E
The American journal of physiology
1997
1997-12
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1152/ajpheart.1997.273.6.h2613" target="_blank" rel="noreferrer noopener">10.1152/ajpheart.1997.273.6.h2613</a>
Daily exercise attenuates the sympathetic nerve response to exercise by enhancing cardiac afferents.
Afferent Pathways; Animal/*physiology; Animals; Baroreflex; Blood Pressure; Femoral Artery/physiology; Femoral Vein/physiology; Heart Rate; Heart/innervation/*physiology; Kidney/innervation; Physical Conditioning; Rabbits; Sympathetic Nervous System/*physiology
"Central command" may initiate the sympathoexcitatory responses at the onset of exercise by shifting the operating point of the arterial baroreflex toward higher pressures. Daily exercise (DE) attenuates the sympathoexcitatory responses to submaximal exercise. This DE-induced adaptation may be due, in part, to an enhanced inhibitory influence of cardiac afferents. This is suggested because cardiac afferents exert a tonic inhibitory influence on the arterial baroreflex which is enhanced by DE. Therefore, the influence of cardiac afferents on the regulation of renal sympathetic nerve activity (RSNA) during exercise was examined in a group of sedentary and age-matched DE rabbits. The rabbits were instrumented with a Silastic catheter inserted into the pericardial sac, electrodes around the renal sympathetic nerves, and catheters in the femoral artery and vein. In the sedentary rabbits, treadmill exercise (12 m/min, 20% grade) significantly increased mean arterial pressure (delta 18 +/- 3 mmHg), heart rate (delta 36 +/- 3 beats/min), and RSNA (delta 295 +/- 23%). More importantly, cardiac afferent blockade (2% intrapericardial procainamide) did not significantly alter the RSNA response to exercise in the sedentary rabbits. DE did not alter the mean arterial pressure (delta 15 +/- 1 mmHg) or heart rate (delta 55 +/- 8 beats/min) response to exercise; however, RSNA (delta 252 +/- 9%) was significantly reduced. In contrast to the sedentary rabbits, cardiac afferent blockade in the DE rabbits significantly increased the RSNA response to exercise (delta 417 +/- 30%). These results suggest that DE attenuates the RSNA response to dynamic exercise due, in part, to an enhanced inhibitory influence of cardiac afferents.
DiCarlo S E; Stahl L K; Bishop V S
The American journal of physiology
1997
1997-09
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1152/ajpheart.1997.273.3.H1606" target="_blank" rel="noreferrer noopener">10.1152/ajpheart.1997.273.3.H1606</a>
Daily spontaneous running attenuated the central gain of the arterial baroreflex.
Animal; Animals; Arteries/*physiology; Baroreflex/*physiology; Brain/*physiology; Female; Male; Motor Activity/*physiology; Physical Conditioning; Rats; Sprague-Dawley
Exercise training attenuates arterial baroreflex function. Mechanisms responsible may include an attenuated aortic baroreceptor reactivity (afferent mechanisms) and/or an attenuated central baroreflex gain. We tested the hypothesis that the aortic baroreceptor reactivity and/or central gain is attenuated by daily spontaneous running (DSR). Eighteen anesthetized Sprague-Dawley rats (11 control and 7 DSR) were tracheotomized and instrumented with femoral venous and right carotid arterial catheters. Electrodes were placed around the left aortic depressor nerve and the lumbar sympathetic trunk. Eight to thirteen weeks of DSR were associated with a 20% increase in heart weight-to-body weight ratio (2.83 +/- 0.04 vs. 3.39 +/- 0.10 g/kg; P \textless 0.001) and resting bradycardia (413 +/- 6 vs. 384 +/- 10 beats/min; P = 0.01). DSR reduced the central gain of the baroreflex regulation of heart rate (0.210 +/- 0.046 vs. 0.005 +/- 0.021 beats.min-1.%-1; P = 0.004) during decreases in arterial pressure. However, the reactivity of aortic baroreceptor afferents and the central gain of the baroreflex control of lumbar sympathetic nerve activity were not different in control and DSR rats. Thus DSR reduced the central gain of the arterial baroreflex regulation of heart rate without changing the reactivity of aortic baroreceptor afferents. We conclude that afferent mechanisms are not responsible for the training-induced reduction in arterial baroreflex function.
Chen C Y; DiCarlo S E; Scislo T J
The American journal of physiology
1995
1995-02
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1152/ajpheart.1995.268.2.H662" target="_blank" rel="noreferrer noopener">10.1152/ajpheart.1995.268.2.H662</a>
Onset of exercise increases lumbar sympathetic nerve activity in rats.
Animal/*physiology; Animals; Blood Pressure; Heart Rate; Lumbar Vertebrae/*innervation; Physical Conditioning; Rats; Sympathetic Nervous System/*physiology
We hypothesized that lumbar sympathetic nerve activity (LSNA) increases at the onset of whole-body dynamic exercise in the rat. To test this hypothesis, we recorded LSNA, heart rate (HR), and arterial pressure (AP) at rest and during a graded exercise test in six adult rats. Rats were instrumented with arterial and venous catheters and recording electrodes around the lumbar sympathetic trunk. Following recovery, each rat ran continuously on a hand-driven or motorized treadmill at 6 m.min-1, 12 m.min-1, and 18 m.min-1 on a 10% grade for approximately 3 min at each workload. Before exercise, mean arterial pressure (MAP), HR, and LSNA averaged 108 +/- 4 mm Hg, 385 +/- 20 bpm, and 100%, respectively. As hypothesized, all variables increased abruptly and dramatically at the onset of treadmill exercise. For example, MAP (117 +/- 5 mm Hg), HR (450 +/- 15 bpm), and LSNA (225 +/- 19%) all increased significantly within the first 25 s of treadmill running at 6 m.min-1. As the exercise continued, there was a progressive increase in HR; however, MAP plateaued at 6 m.min-1 and LSNA plateaued at 12 m.min-1. Since LSNA increased at the onset of whole-body dynamic exercise in the rat, we suggest that the increase in LSNA at the onset of exercise is mediated by a central (feed forward) mechanism.
DiCarlo S E; Chen C Y; Collins H L
Medicine and science in sports and exercise
1996
1996-06
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1097/00005768-199606000-00006" target="_blank" rel="noreferrer noopener">10.1097/00005768-199606000-00006</a>