侧脑室及下丘脑视前区微量注射孤啡肽对大鼠血压、心率的影响

孤啡肽（OrphaninFQ,OFQ）是1995年底发现的内阿片肽,一级结构与强啡肽A很相似,但生物学作用与其它内阿片肽有所不同。本工作采用侧脑室及核团微量注射的方法,观察了中枢OFQ对大鼠心血管活动的影响。结果表明：侧脑室注射1、10μgONQ可明显降低大鼠平均动脉压（MAP）及心率（HR）;侧脑室预先注射4μg纳洛酮不影响1μgOWQ的降压及减慢心率的效应。下丘脑视前区（POA）微量注射1μgOFQ也可降低血压、减慢心率。结果表明,中枢OFQ与其它内阿片肽相似,可抑制心血管活动,且其抑制作用不是通过μ、δ、κ阿片受体介导。POA为中枢OFQ抑制心血管活动的靶区之一。     

The extended amygdala system and self-stimulation of the lateral hypothalamus in rats: modulation with opiates and opioids

Wistar male rats were implanted with bipolar electrodes in the lateral hypothalamus to study self-stimulation reaction in the Skinner box. Simultaneously, the microcanules were implanted into the central nucleus of the amygdala to inject the drugs studied (1 microl in volume for each injection). The blockade of CRF receptors (astressin 1 microg) or sodium influx ionic currents (xycaine, or lidocain 1 microg) by means of intrastructural administration of drugs into the amygdala descreased self-stimulation reaction of the lateral hypothalamus in rats by 29-55%. The inhibition of D2 and D2 dopamine receptors in the amygdala with SCH23390 (1 microg) or sulpiride (1 microg), respectively. reduced self-stimulation too, but in less degree. On the background of blockade of CRF (astressin) and dopamine (sulpiride) receptors, as well as sodium influx ionic currents (lidocain) in the amygdala neurons, psychomotor stimulant amphetamine (1 mg/kg) and barbiturate sodium ethaminal (5 mg/kg) supported their psychoactivating effect on self-stimulation (+30-37%), but fentanyl (0.1 mg/kg) had got no effect. Fentanyl activated self-stimulation moderately only after blockade D1 dopamine receptors with SCH23390. After blockade of CRF receptors, leu-enkephaline strengthened its depressant effect on self-stimulation reaction (-89%). Therefore, if the modulating influence of the amygdala on the hypothalamus is diminished, the reinforcing effects of opiated (fentanyl) and opioids (leuencephaline) will block, but there will be no effect for psychomotor stimulant amphetamine and barbiturate sodium ethaminal.     

Effects of intrahypothalamic testosterone implants on LHRH levels in the preoptic area and the medial basal hypothalamus.

Following castration LHRH levels in the MBH but not in the POA decreased. Testosterone implants in the medial POA following castration failed to alter the LHRH activity either locally in the POA or in remote sites in the MBH. On the contrary, similar T implants in the MBH blocked castration-induced depletion of MBH LHRH stores without affecting either the POA LHRH content or the post-castration hypersecretion of pituitary LH. These findings identify the MBH as the focal site of T action in the regulation of hypothalamic LHRH activity.     

Changes in blood pressure, heart rate and blood constituents during heat exposure in men with elevated blood pressure

Although the vascular volume response of hypertensive men during exercise has been rather well characterized, the effect of resting heat exposure in this patient population has not been examined. This was done in the present report in seven men with high blood pressure (BP) (i.e., diastolic pressure greater than 12 kPa (90 mmHg) upon initial interview) and 5 normotensive control subjects. 50 min after each subject had consumed an amount of water equal to 1% of his body weight, he reclined on a cot. 10 min later the subject was carried into an environmental chamber equilibrated at Tdb = 45 degrees C, Twb = 28 degrees C. Free-flowing venous blood samples were obtained from a cubital vein, and BP and heart rate were measured, before the heat exposure and at 15 min intervals during the experiment. Within 30 min systolic, diastolic and mean BP of the high BP subjects had decreased to normal levels; no BP changes were detected in normotensive subjects. Accompanying this depressor response was an exaggerated elevation in plasma glucose concentration. No alterations were found with haematocrit, plasma osmolality or electrolytes, or total protein and albumin. The data suggest that heat exposure may have been more stressful for the subjects with high BP than for their controls. This finding implies that phasic depressor responses may be as important as phasic pressor episodes in the aetiology of established essential hypertension.     

Attenuation of morphine analgesia by lesions of the preoptic forebrain region in the rat.

Latency to tail withdrawal from hot water was measured as a pain response before and after morphine injection in female rats. Morphine increased the withdrawal latency. Lesions in the preoptic forebrain region attenuated morphine analgesia.     

Heart rate and blood pressure changes during radiofrequency irradiation and environmental heating.

1. Whole-body exposure of animals to radiofrequency radiation (RFR) can cause an increase in body temperature. 2. Responses to heating, whether due to RFR or to more conventional means, include changes in heart rate and blood pressure. 3. Although cardiovascular responses to various types of heating are similar, differences in the magnitude of changes may result from different thermal gradients within the body. 4. This review compares the effects of RFR and conventional environmental heating on heart rate and blood pressure.     

Infusions of naloxone into the medial preoptic area,ventromedial nucleus of the hypothalamus,and amygdala block conditioned place preference induced by paced mating behavior

Paced mating induces positive affect as revealed by conditioned place preference (CPP) in female rats. It has been suggested that endogenous opioids are involved in the generation of this positive affect since systemic administration of the opioid antagonist naloxone blocks mating-induced CPP. Several brain structures, including the medial preoptic area (mPOA), the ventromedial nucleus of the hypothalamus (VMH), the amygdala (Me), and the nucleus accumbens (Acb) have been implicated in the control of female sexual behavior. However, it is not known if these structures also participate in the positive affect produced by paced mating. To this end we determined the effects of intracranial administration of naloxone methiodide into the mPOA, VMH, Me and Acb on conditioned place preference induced by paced mating in female rats. Regardless of the site of infusion 5 μg of naloxone did not affect any of the sexual behavior parameters measured during copulation. When CPP was evaluated, the groups infused with naloxone into the mPOA, the VMH, and the Me before each conditioning session did not develop place preference. Only the group infused with naloxone in the Acb and the control groups did so. These results demonstrate that opioid receptors within the mPOA, VMH and Me are necessary for the rewarding aspects of paced mating. We suggest that the Me and VMH are important for the transmission of sensory information produced by copulation while the mPOA is the site where the positive affect is originated.     

Infusions of naloxone into the medial preoptic area, ventromedial nucleus of the hypothalamus, and amygdala block conditioned place preference induced by paced mating behavior

Paced mating induces positive affect as revealed by conditioned place preference (CPP) in female rats. It has been suggested that endogenous opioids are involved in the generation of this positive affect since systemic administration of the opioid antagonist naloxone blocks mating-induced CPP. Several brain structures, including the medial preoptic area (mPOA), the ventromedial nucleus of the hypothalamus (VMH), the amygdala (Me), and the nucleus accumbens (Acb) have been implicated in the control of female sexual behavior. However, it is not known if these structures also participate in the positive affect produced by paced mating. To this end we determined the effects of intracranial administration of naloxone methiodide into the mPOA, VMH, Me and Acb on conditioned place preference induced by paced mating in female rats. Regardless of the site of infusion 5 μg of naloxone did not affect any of the sexual behavior parameters measured during copulation. When CPP was evaluated, the groups infused with naloxone into the mPOA, the VMH, and the Me before each conditioning session did not develop place preference. Only the group infused with naloxone in the Acb and the control groups did so. These results demonstrate that opioid receptors within the mPOA, VMH and Me are necessary for the rewarding aspects of paced mating. We suggest that the Me and VMH are important for the transmission of sensory information produced by copulation while the mPOA is the site where the positive affect is originated.     

Peptide injections into the amygdala of conscious rats: effects on blood pressure, heart rate and plasma catecholamines

The central nucleus of the amygdala (Ce) mediates cardiovascular and autonomic changes associated with defense or fear responses. At least 16 different neuropeptides have been identified within nerve terminals within the Ce. The role that these peptides play in the Ce regulation of cardiovascular and autonomic function has been assessed. Neuropeptides were microinjected into the region of the Ce and mean arterial pressure (MAP), heart rate (HR) and plasma catecholamine concentrations were measured. Five of the 16 peptides caused changes of MAP and HR. Thyrotropin releasing factor (TRF) and calcitonin gene-related peptide (CGRP) induced increases of MAP and HR. Angiotensin-II (A-II) and somatostatin-28 (SS-28) injection produced increases of MAP and decreases of HR. Bombesin (Bom) injections into the Ce induced an increase of MAP but did not alter HR. Corticotropin releasing factor (CRF), TRF and CGRP were the only peptides found to increase plasma catecholamine concentrations. These results support the conclusion that the Ce contains several peptides that could be involved in the regulation of cardiovascular and autonomic nervous system function. A role of the amygdala in mediating the observed effects of CRF, TRF, CGRP, A-II, SS-28, and Bom is suggested by these studies.     

Ranges of diurnal variation and the pattern of body temperature, blood pressure and heart rate in laboratory beagle dogs.

Ranges in diurnal variation and the patterns of body temperature (T), blood pressure (BP), heart rate (HR) and locomotor activity (LA) in 61 laboratory beagle dogs were analyzed using a telemetry system. Body temperature, BP, HR and LA increased remarkably at feeding time. Locomotor activity increased sporadically during the other periods. Body temperature was maintained at the higher value after feeding but had decreased by 0.2 C by early the next morning. Blood pressure fell to a lower value after feeding but had increased by 2.8% by early the next morning. Heart rate decreased progressively after feeding and was 14.5% lower the next morning. This study determined that in laboratory beagles the ranges of diurnal variation and patterns of T, BP and HR are significantly different from those reported in humans and rodents, and that over 24 hr these physiological changes were associated with their sporadic wake-sleep cycles of the dogs.     

Changes in arterial blood pressure, heart rate and haematocrit during acute hyperkalaemia in conscious sheep.

The systolic, diastolic and mean arterial blood pressures, heart rate and haematocrit were measured at 15 minute intervals before, during and after 2 hour infusions of 0-4 mol.l-1 NaCl at 2-2 ml min-1 into conscious intact sheep and 0-4 mol. l-1 KCl at 2-2 ml. min-1 into conscious sheep which were either intact or adrenalectomized. The haemotocrit was also measured in splenectomized sheep receiving 0-4 mol. l-1 KCl. The NaCl infusion had no significant effect on blood pressure(BP), heart rate and haematocrit. Both intact and adrenalectomized sheep were able to withstand an increase in plasma potassium concentration in excess of 50% of the preinfusion concentration before any substantial fall in BP occurred. In intact and adrenalectomized sheep, heart rate and haematocrit increased rapidly and progressively throughout the potassium infusions and at maximum plasma potassium concentration the mean increments in these parameters for both groups of sheep were 21-6+/-2-69 beats/min and 7-5+/-0-47% respectively. Heart rate and haematocrit were more closely correlated with the plasma potassium concentration than with any other variable measured in these experiments. Adrenalectomy did not reduce the ability of the sheep to maintain their BP or to increase their heart rate and haematocrit. As the mean increase in haematocrit during potassium infusion into splenectomized sheep was 1-3+/-0-45% most of the increase in haematocrit observed in the potassium-infused intact and adrenalectomized sheep was caused by ejection of red cells from the spleen into the circulation.     

Baroreflex modulation of ultradian oscillations of blood pressure and heart rate in unanesthetized dogs

Telemetered, free-running dogs were studied to determine the role of cardiovascular control systems in modulation of ultradian oscillations of arterial pressure (MAP) and heart rate (HR). Data, aquired (2 Hz) by a stable telemetry system, was stored on a digital computer and analyzed for its harmonic content by a Fast Fourier Transform (FFT) algorithm. Both AP and HR consistently demonstrated rhythms having a period of from 0.6 to 1.0 h. Modulation of these rhythms by arterial pressure control systems was assessed in dogs studied before and carotid sinus baroreceptor denervation, before and after denervation of the aortic arch baroreceptors and before and after a combination of both these procedures. The data indicate the power spectral density (PSD) of MAP, but not HR, is increased (p less than 0.05) after denervation of the carotid sinuses alone, while the primary frequency of the oscillations was unchanged. On the other hand, denervation of the aortic arch baroreceptors alone was without effect on either the frequency or PSD of these oscillations. A combination of both carotid sinus and aortic arch denervation resulted in an increased (p less than 0.05) PSD of MAP oscillations but not in their frequency. These data indicate that the carotid sinuses modulate rhythmic behavior of MAP by buffering the magnitude, but not frequency, of the oscillations. Moreover, since oscillations were present in dogs after denervation of both the carotid sinus and aortic arch baroreceptors, these ultradian oscillations are not a result of a non-linear negative feedback mechanisms arising from these pressure sensitive regions.     

Impact of acute hypoxia on heart rate and blood pressure variability in conscious dogs

To examine whether the impacts of hypoxia on autonomic regulations involve the phasic modulations as well as tonic controls of cardiovascular variables, heart rate, blood pressure, and their variability during isocapnic progressive hypoxia were analyzed in trained conscious dogs prepared with a permanent tracheostomy and an implanted blood pressure telemetry unit. Data were obtained at baseline and when minute ventilation (VI) first reached 10 (VI10), 15 (VI15), and 20 (VI20) l/min during hypoxia. Time-dependent changes in the amplitudes of the high-frequency component of the R-R interval (RRIHF) and the low-frequency component of mean arterial pressure (MAPLF) were analyzed by complex demodulation. In a total of 47 progressive hypoxic runs in three dogs, RRIHF decreased at VI15 and VI20 and MAPLF increased at VI10 and VI15 but not at VI20, whereas heart rate and arterial pressure increased progressively with advancing hypoxia. We conclude that the autonomic responses to isocapnic progressive hypoxia involve tonic controls and phasic modulations of cardiovascular variables; the latter may be characterized by a progressive reduction in respiratory vagal modulation of heart rate and a transient augmentation in low-frequency sympathetic modulation of blood pressure.     

Acoustic modulation of neural activity in the preoptic area and ventral hypothalamus of the green treefrog (Hyla cinerea)

Summary Responses of neurons in the preoptic area and ventral hypothalamus to conspecific mating calls or white noise bursts were examined in male green treefrogs (Hyla cinerea) during different seasons. In the winter, 34.3% of preoptic neurons and 46.7% of ventral hypothalamic cells demonstrated significant changes in activity level during presentation of a conspecific mating call. In contrast, only 13.3% of preoptic units and 16.7% of ventral hypothalamic cells responded to the white noise. The percentage of preoptic and hypothalamic units responding to the advertisement call did not differ significantly during the summer breeding season. Type I units exhibited a dramatic increase in activity during acoustic stimulation followed by a rapid return to baseline activity levels after stimulus offset. Type II cells showed a robust activity increase during stimulation, but maintained an intermediate activity level after stimulus offset. In the preoptic area, a third response type exhibited suppressed activity during acoustic stimulation. Although seasonal condition did not alter the percentage of acoustically responsive units within either nucleus, the proportion of Type I units in the ventral hypothalamus was greatest during the summer.Abbreviations MC mating call - NS no stimulus - POA preoptic area - VH ventral hypothalamus - WN white noise     

Inhibition of the preoptic area and anterior hypothalamus by tetrodotoxin alters thermoregulatory functions in exercising rats.

We have previously demonstrated a functional role of the preoptic area and anterior hypothalamus (PO/AH) in thermoregulation in freely moving rats at various temperature conditions by using microdialysis and biotelemetry methods. In the present study, we perfused tetrodotoxin (TTX) solution into the PO/AH to investigate whether this manipulation can modify thermoregulation in exercising rats. Male Wistar rats were trained for 3 wk by treadmill running. Body core temperature (Tb), heart rate (HR), and tail skin temperature (Ttail) were measured. Rats ran for 120 min at speed of 10 m/min, with TTX (5 microM) perfused into the left PO/AH during the last 60 min of exercise through a microdialysis probe (control, n=12; TTX, n=12). Tb, HR, and Ttail increased during the first 20 min of exercise. Thereafter, Tb, HR, and Ttail were stable in both groups. Perfusion of TTX into the PO/AH evoked an additional rise in Tb (control: 38.2 +/- 0.1 degrees C, TTX: 39.3 +/- 0.2 degrees C; P <0.001) with a significant decrease in Ttail (control: 31.2 +/- 0.5 degrees C, TTX: 28.3 +/- 0.7 degrees C; P <0.01) and a significant increase in HR (control: 425.2 +/- 12 beats/min, TTX: 502.1 +/- 13 beats/min; P <0.01). These results suggest that the TTX-induced hyperthermia was the result of both an impairment of heat loss and an elevation of heat production during exercise. We therefore propose the PO/AH as an important thermoregulatory site in the brain during exercise.