Prenatal influence of mild decompressions on hooded rats

Frequent, brief, and mild prenatal decompressions caused decreases in newborn rats' viability and in survivors' “emotional” development. Both hypoxia and otic barotrauma contributed to these effects, but hypoxia, alone, did not affect offspring behavior in the open field or in a shock avoidance task.     

Histopathologic and histobacteriologic studies of chronic periapical changes of the permanent teeth

Chronic periapical lesions were recognized clinically and radiologically in 109 patients aged from 10 to 79, twice as frequent in the maxilla as in the mandible. Histopathological analysis revealed periapical granulomas and cysts. Forty-eight periapical granulomas were studied histobacteriologically. Detailed microscopic analysis of these cases in order to find bacteria was negative. Histopathological analysis of 72 periapical granulomas and 13 cysts (including four follicular cysts) revealed mixed forms apart from homogenous granulomas. In addition changes in the composition of infiltrate cells are rather qualitative than quantitative, therefore classification of periapical lesions into periapical granulomas and cysts seems justified and sufficient for diagnostic and clinical needs. Detailed analysis of cellular composition of periapical granulomas and cysts shows that immunologic agents may play a role in the pathomechanism of these lesions.     

Histopathologic changes of the spleen in suckling rats inoculated with Hantaan virus.

The purpose of this study is to delineate the histopathologic findings of the spleen after Hantaan viral inoculation, which is the largest lymphoid organ in rats, and to identify the viral location by anti-Hantaan virus (HTNV) monoclonal antibody. All the sixty one suckling rats of less than twenty four hours of age were used. Except twenty one rats of control group, twenty-five rats inoculated intracerebrally for the early change and fifteen suckling rats inoculated intramuscularly for the late change were uniformly susceptible to lethal infection with the ROK 84-105-1 strain of seed HTNV. The characteristic histopathologic findings were; appearance of macrophages below the splenic capsule on the 3rd day, small lymphocytes around the periarteriolar sheath on the 5th day increasing in numbers on the 7th day, and a markedly expanded marginal zone with some immunoblasts and plasma cells as well as decreased extramedullary hematopoiesis on the 9th and 14th days. Time of onset of histopathologic changes in spleen thickness, appearance of medium and large lymphocytes and degree of extramedullary hematopoiesis were influenced by inoculation route, whereas expansion of the marginal zone was affected by postnatal age.     

Histopathologic changes of uterus following gossypol treatment during early pregnancy in rats

Intramuscular injections of gossypol acetic acid (25 mg in 10% EtOH/kg/day beginning on day 2 of diestrus) disrupted early pregnancy in rats as determined by light and electron microscopy. As in pregnant controls, in the uteri of treated rats increased glandular secretion, stromal hyperemia, and decidual tissue formation were noted at days 3-5 of pregnancy. At day 6, extreme hyperemia and stromal hemorrhage had occurred around well-developed decidual tissue with foci of denuded mucosal surface. There was extravasation of blood into the uterine lumen, which was absent in controls. At days 5 and 6 of pregnancy, electron microscopy revealed shorter and fewer microvilli on the uterine glandular cells in the treated versus the control uterus. Luminal epithelial cells had not undergone the normal changes of pregnancy. These results imply that gossypol administered under our conditions neither prevented nor delayed implantation and formation of decidual tissue in the rat uterine endometrium but continuing development of the endometrium was disrupted at day 6 of pregnancy. This disruption of pregnancy may have resulted from a luteolytic action by gossypol that would not permit full structural differentiation in the rat uterus after implantation.     

Reflex changes in the activity of the cardiovascular system under the influence of chemical stimulation of pericardial receptors

Summary Experiments were performed on cats under urethan anesthesia and on cats with normal respiration.Pericardial receptors stimulated by nicotine (0.4·10^–9 to 1·10^–3) cause pronounced reflex changes in the level of the blood pressure, heart rate and respiration. In 60% of experiments, stimulation of pericardial receptors by weak concentrations of nicotine caused increase of the blood pressure and tachycardia, while stimulation by strong concentrations of nicotine resulted in reflex decrease of the blood pressure and bradycardia. In 25% of the experiments, the animals reacted by pressor reactions and tachycardia when pericardial receptors were stimulated [by any concentration of nicotine. In 15% of the experiments, any stimulation of these receptors by nicotine caused depression of the cardiovascular system. In all experiments, any chemical stimulation of pericardial receptors both by weak and strong solutions caused increase of the rate and depth of respiratory movements.It is suggested that the change of the pressor reaction into depressor is caused not by the stimulation of different types of receptors, but depends on the more intense stimulation of a large number of similar receptors.Presented by Active Member Acad. Med. Sci. USSR, V. N. Chernigovskii     

Histologic and histochemical changes in the aorta and myocardium of rats under the influence of atherogenic diet and phosphatidylcholine (EPL).

The prophylactic and therapeutic action of EPL on arteriosclerotic changes induced with fat-rich diet in the aorta and myocardium of white rats was studied. Histologic and histochemical studies showed that EPL administered prophylactically in doses of 280 mg/kg and 900 mg/kg body weight does not significantly inhibit development of arteriosclerotic lesions if fat-rich diet is continued. A distinct prophylactic action of EPL was first seen at a dosage of 2800 mg/kg. The therapeutic action of EPL on pathologic changes in the blood vessels also depends on dosage. The higher the dosage of EPL, the less pronounced the changes. At a dosage level of 2800 mg/kg, changes are slight and sporadic.     

Metyrapone-induced cardiovascular degenerative changes in non-arteriosclerotic and arteriosclerotic rats

Virgin and breeder, male and female, Sprague-Dawley rats were unilaterally nephrectomized and given 1% saline drinking water. Animals were injected i.p., twice daily, with a 10 mg/100 g body wt dose of the 11-beta hydroxylation inhibitor, Metyrapone. After 7 weeks of treatment, both the previously nonarteriosclerotic virgin rats and the breeder rats with pre-existing arteriosclerosis developed de nove, widely distributed, intimal hyalinization of their peripheral arteries along with myocardial fibrosis and hyalinization of their intramyocardial coronary arteries. The Metyrapone-treated animals developed severe hypertension with greatly elevated serum creatin phosphokinase, glucose, BUN and cholesterol levels. The adrenal glands, hearts, and kidneys were greatly hypertrophied, in keeping with Metyrapone-induced extra ACTH release and the hypertension-induced myocardial and renal histopathology. Uniparous, Metyrapone-treated, female rats manifested an unusually high incidence of saccular aneurysms of the aorta. It is suggested that the hypertension and the intimal hyalinization and other specific morphologic characteristics of the cardiovascular degenerative changes observed were directly related to excess production of mineralocorticoids, e.g., deoxycorticosterone.     

Behavioral and cardiovascular changes in the chronic mild stress model of depression

Depression is a multifaceted psychological disorder that involves changes in behavior, neuroendocrine function, and physiological responses. The present study investigated multiple behavioral and cardiovascular consequences in the chronic mild stress (CMS) rodent model of depression. Rats were exposed to 4 weeks of CMS followed by 4 weeks of a stress-free recovery period. Sucrose intake, a measure of anhedonia, and spontaneous locomotor activity were measured weekly throughout the study, and cardiovascular function tests were conducted at the completion of the protocol. The results indicate that CMS results in anhedonia and reduced locomotor activity, as well as elevated heart rate (HR), reduced HR variability, and elevated sympathetic cardiac tone. The behavioral effects of CMS recovered to baseline (prestress) levels during the recovery period; however, cardiovascular changes were observed following the recovery of sucrose intake and activity levels. The present findings suggest that behavioral changes that are indicative of anhedonia and locomotor alterations associated with depression are dissociable from long-term cardiovascular changes induced by CMS.     

Effects of sectioning the corpus callosum on interocular transfer in hooded rats

Summary After learning a vertical/horizontal visual discrimination with one eye rats were tested on the same or the reverse discrimination with the second eye. Positive but imperfect savings were found in transfer rats and zero savings in reversal rats. However, there were no differences between the savings scores of normal rats and rats with section of the corpus callosum. When the first eye was subsequently retested, the normal rats which had learned the reverse discrimination with the second eye were significantly worse than those tested on transfer with the second eye, whereas no such difference occurred in the operated groups. It is argued that the uncrossed optic pathway is responsible for the indistinguishable performance of normal and operated rats on second eye performance, but that performance when the first eye is retested is now influenced by callosal fibres connecting primary traces in each hemisphere.     

Acoustically elicited behaviours in Lister hooded and Wistar rats

It has been reported previously that experimenter-presented 20-kHz tones at low intensities produce bursts of locomotor running in Lister hooded rats, but reduced locomotion (freezing) in Wistar rats. Because rats emit 20-kHz tones when stressed, it was proposed that this ultrasound-elicited running and freezing behaviour in Lister hooded and Wistar rats, respectively, represents a model for qualitative strain differences in fear behaviour. The present studies examined the acoustic specificity of acoustically elicited locomotor behaviours in Lister hooded and Wistar rats. In Experiment 1, it was found that brief exposure (i.e., 15 s) of Lister hooded rats to tones at frequencies of 7, 12, or 20 kHz and intensities of 85-95 dB SPL, elicited running behaviour characterised by brief bursts of locomotion followed by periods of quiescence. Somewhat surprisingly, the 7- and 12-kHz tones elicited running behaviour at lower intensities than did the 20-kHz tones. In Experiment 2, it was found that exposure of Lister hooded rats to the 20-kHz acoustic stimulus (91-101 dB, SPL) for a much longer duration, up to 9 min, resulted in episodic bursts of locomotion and convulsions in a significant proportion of subjects. Both the maximal velocity of locomotion and the likelihood of occurrence of convulsions was related to the intensity of the acoustic stimulus. Exposure of Lister hooded rats to white noise for up to 9 min also elicited episodic bursts of locomotion and convulsions in an intensity-dependent manner. The white noise stimulus was found to be a more effective stimulus than the 20-kHz stimulus in this regard. In Experiment 3, it was found that Lister hooded rats exhibited reduced locomotion when they were exposed to a low-intensity 20-kHz acoustic stimulus (e.g., 81 dB, SPL). In Experiment 4, it was found that Wistar rats did not exhibit locomotor bursts or convulsions when presented with 20-kHz tones using stimulus parameters equal to and even greater than those that had been shown to be effective in producing locomotor bursts in Lister hooded rats. Rather, Wistar rats exhibited only reduced locomotion. The present data indicate that (1) running behaviour in Lister hooded rats is not specific for the 20-kHz stimulus. Moreover, (2) when compared to Lister hooded rats, Wistar rats are relatively insensitive to the running and convulsions elicited by acoustic stimuli. Finally, (3) both Lister hooded and Wistar rats exhibited reduced locomotion when presented with the 20-kHz tones, although the range of stimulus intensities that produces freezing behaviour is much more limited in Lister hooded rats because of their propensity to exhibit locomotor bursting and convulsions. Thus, it appears that the difference between the two strains with respect to their unconditioned locomotor responses to novel acoustic stimuli relates to the fact that Lister hooded rats are uniquely susceptible to acoustically elicited locomotor bursts and/or convulsions.     

Functional and structural changes in the ovaries of rats fed a well-balanced diet after being kept on a protein-deficient diet

Summary Sexually mature and immature rats kept for a long time on a diet deficient in protein (1.5% protein) were fed a control diet of 19.5% protein content. The functions, relative and absolute weight of the ovaries were restored. The microscopic structure of the organ was restored, likewise the growth processes and follicular differentiation were resumed. In comparison with the period of dificiency the number of oocytes markedly increased.Presented by Prof. N. N. Zhukov-Verezhnikov, Active Member of the USSR Academy of Medical Sciences     

The effects of olfactory system lesions and food deprivation on spontaneous behavior patterns of male hooded rats

The behavior of normal male rats was observed in an exploration field in which a number of olfactory cues were present. Locomotor activity, freezing, grooming, sniffing, rearing and boluses dropped were quantified over days and correlations between them were obtained. Following olfactory nerve sections at the bulb surface or total olfactory bulb and peduncle destruction, the measures were made again and lesion induced changes in them and olfactory cue exploration were noted. After a period of food deprivation, the measures were made a third time to assess possible motivational factors on the results. Both lesions and food deprivation altered many variables with the deeply lesioned animals more affected than the shallowly lesioned animals. Possible interactions between partial or complete anosmia and lesion induced changes in reactivity were considered. Some problems associated with the production of and tests for anosmia were also discussed.     

Properties of ipsilateral retinogeniculate afferents in albino and hooded rats

By recording single unit activities from the dorsal lateral geniculate nucleus in albino and hooded rats, physiological properties of the ipsilateral retinogeniculate afferents were compared with those of the contralateral ones. The results show that the ipsilateral retinogeniculate pathway was characterized by intermediate conduction velocities, relatively high incidence of the tonic response and the visual field representation of central 30° from the vertical midline on both sides.     

Comparative effects of hydralazine and captopril on the cardiovascular changes in spontaneously hypertensive rats.

Vascular changes that develop during the course of blood pressure rise in spontaneously hypertensive rats (SHRs) can be modified by antihypertensive therapy. It is not known, however, whether there is selectivity in the structural response to specific antihypertensive drugs. This issue was examined by comparing the effects of a direct vasodilator (hydralazine) and a converting enzyme inhibitor (captopril) on morphologic aspects of the cardiovascular system. Male SHRs, 21 weeks of age, were given either hydralazine (HCl plus hydrochlorothiazide, captopril plus hydrochlorothiazide, or hydrochlorothiazide alone. Untreated age-matched SHRs and Wistar-Kyoto normotensive rats (WKYs) were used as controls. Animals were sacrificed at 27-28 weeks of age. Both hydralazine and captopril lowered significantly the blood pressure of SHRs, whereas hydrochlorothiazide alone was ineffective. The heart/body weight ratios were dramatically reduced in captopril-treated SHRs to below the level of WKYs; hydralazine induced only a very modest (5%) reduction, whereas the diuretic alone was ineffective. The morphology of the aortic intima improved dramatically in response to captopril and hydralazine and, to a lesser extent, hydrochlorothiazide alone. This effect becomes apparent within 6 weeks of treatment, and the only evidence of preexisting disease is the persistence of collagen in the subendothelium. Captopril and hydralazine, but not hydrochlorothiazide alone, reduce the thickness of the aortic media below that of normotensive controls. In addition, captopril and hydralazine improve the structure of small intrarenal vessels. There was a strong correlation between the relative effectiveness of the three pharmacologic agents in lowering blood pressure and in improving the changes of intrarenal vessels. These results highlight the capacity of antihypertensive therapy to arrest or reverse the structural sequelae of hypertension. In addition, they underscore the heterogeneity in the response of different components of the cardiovascular system, which, in part, reflects selectivity in the action of antihypertensive agents.     

Metyrapone-induced cardiovascular degenerative changes in non-arteriosclerotic and arteriosclerotic rats.

Virgin and breeder, male and female, Sprague-Dawley rats were unilaterally nephrectomized and given 1% saline drinking water. Animals were injected i.p., twice daily, with a 10 mg/100 g body wt dose of the 11-beta hydroxylation inhibitor, Metyrapone. After 7 weeks of treatment, both the previously nonarteriosclerotic virgin rats and the breeder rats with pre-existing arteriosclerosis developed de nove, widely distributed, intimal hyalinization of their peripheral arteries along with myocardial fibrosis and hyalinization of their intramyocardial coronary arteries. The Metyrapone-treated animals developed severe hypertension with greatly elevated serum creatin phosphokinase, glucose, BUN and cholesterol levels. The adrenal glands, hearts, and kidneys were greatly hypertrophied, in keeping with Metyrapone-induced extra ACTH release and the hypertension-induced myocardial and renal histopathology. Uniparous, Metyrapone-treated, female rats manifested an unusually high incidence of saccular aneurysms of the aorta. It is suggested that the hypertension and the intimal hyalinization and other specific morphologic characteristics of the cardiovascular degenerative changes observed were directly related to excess production of mineralocorticoids, e.g., deoxycorticosterone.     

Effects of 50-Hz magnetic field on the cardiovascular system in rats

AIM: The 50-Hz magnetic field( MF) is a potential health-risk factor. Its effects on the cardiovascular system have not been fully investigated. This study was conducted to explore the effects of long-term exposure to 50-Hz MF on the cardiovascular system.METHODS: In the study,an exposure system was constructed and the distribution of 50-Hz MF was detected. Sixty-four SpragueDawley( SD) rats were exposed to 50-Hz MF at 100 μT for 24 weeks,20 hours per day,while another 64 rats were sham exposed.During the exposure,blood pressure was measured every 4 weeks,and 24 weeks later,echocardiography,cardiac catheterisation and electrocardiography were performed. Moreover,heart and body weight were recorded,while haematoxylin-eosin staining and real-time PCR were conducted. RESULTS: The results showed that compared with the sham group,exposure to 50-Hz MF did not exert any effect on blood pressure,pulse rate,heart rate and cardiac rhythm. Further,echocardiography and cardiac catheterisation showed that there were no significant differences in the cardiac morphology and haemodynamics. In addition,histopathological examination showed that 50-Hz MF exposure had no effect on the structure of hearts. Finally,the expression of the cardiac hypertrophic relative genes did not show any significant differences between 50-Hz MF exposure group and the sham group. CONCLUSION: Taken together,in SD rats,exposure to 50-Hz /100-μT MF for 24 weeks did not show any obvious effects on the cardiovascular system.