The behavior of the homozygous and heterozygous sub-types of rats which are genetically-selected for diabetes insipidus: A comparison with Long Evans and Wistar stocks

Several aspects of spontaneous and conditioned behavior (food and water intake, locomotion and emotionality, passive and active avoidance acquisition and retention) of standard (albino and pigmented) rats, and rats heterozygous (HEDI) and homozygous (HODI) for diabetes insipidus, are reviewed. As would be expected, HODI rats have been repeatedly found to consume far more fluid than either HEDI or control rats. Pigmented rats appear to be more active than albinos. HODI rats exhibit less marked emotional responses than do control rats, among which the pigmented ones exhibit the highest emotionality. Light aversion is more evident in albino than in pigmented rats. No differences are found among HEDI, HODI and normal Long Evans rats. It is quite difficult to provide a clear-cut statement concerning inter-strain differences in passive avoidance behavior, possibly because of the variety of techniques employed. In any case, HODI rats do not perform worse than normal controls do. In one-way active avoidance paradigms, pigmented rats perform better than albinos, and the performance of HODI rats does not differ from that of controls. In two-way avoidance paradigms, albinos appear to outperform pigmented rats. Once again, there are no obvious differences between HODI and control animals.In addition to indicating that HODI rats may actually be less emotional than the other groups of rats reviewed here, the studies described once again fail to confirm the previously alleged functions of vasopressin in memory consolidation.     

The behavior of the homozygous and heterozygous sub-types of rats which are genetically-selected for diabetes insipidus: a comparison with Long Evans and Wistar stocks

Several aspects of spontaneous and conditioned behavior (food and water intake, locomotion and emotionality, passive and active avoidance acquisition and retention) of standard (albino and pigmented) rats, and rats heterozygous (HEDI) and homozygous (HODI) for diabetes insipidus, are reviewed. As would be expected, HODI rats have been repeatedly found to consume far more fluid than either HEDI or control rats. Pigmented rats appear to be more active than albinos. HODI rats exhibit less marked emotional responses than do control rats, among which the pigmented ones exhibit the highest emotionality. Light aversion is more evident in albino than in pigmented rats. No differences are found among HEDI, HODI and normal Long Evans rats. It is quite difficult to provide a clear-cut statement concerning inter-strain differences in passive avoidance behavior, possibly because of the variety of techniques employed. In any case, HODI rats do not perform worse than normal controls do. In one-way active avoidance paradigms, pigmented rats perform better than albinos, and the performance of HODI rats does not differ from that of controls. In two-way avoidance paradigms, albinos appear to outperform pigmented rats. Once again, there are no obvious differences between HODI and control animals. In addition to indicating that HODI rats may actually be less emotional than the other groups of rats reviewed here, the studies described once again fail to confirm the previously alleged functions of vasopressin in memory consolidation.     

Effects of epinephrine on plasma fibrinogen levels in rats submitted to tissue injury

Summary Tissue injury (laparotomy) produces an increase in plasma fibrinogen. This increase is inhibited by the removal of the adrenal medulla, but injection of epinephrine in laparotomized-medullectomized rats returns fibrinogen levels to values similar to those observed in only laparotomized rats. Epinephrine administration to laparotomized rats increases the fibrinogen compared with the group of laparotomized rats without treatment, but epinephrine by itself does not modify plasma fibrinogen levels in uninjured rats. Epinephrine is apparently responsible for the increase of plasma fibrinogen in rats subjected to tissue injury, probably through beta adrenergic stimulation.     

Variations in cardiac noradrenaline content during sodium loading in hypertension prone and resistant rats

Summary The cardiac catecholamine content of Sabra rats and their 2 genetically derived substrains, hypertension prone and resistant rats, was studied by high pressure liquid chromatography and electrochemical detection. Both in the control period and after sodium and DOCA administration the cardiac noradrenaline level is higher in hypertension resistant rats than in Sabra rats, and also higher than in hypertension prone rats. This finding suggests that a reduction of the cardiac sympathetic nervous tone is involved in the genetic resistance to sodium.     

New bone induction by demineralized bone matrix in immunosuppressed rats.

Subcutaneous implantation of demineralized bone matrix (DBM) initiates a sequence of developmental events which culminate in endochondral bone formation. To test the effects of T-cell deficiency on new bone formation, the morphology of DBM-induced bone was examined in rats thymectomized at three weeks of age and in thymectomized or nonthymectomized rats lethally irradiated and reconstituted with syngeneic bone marrow. At 24 days after implantation, bone induction in control rats was appropriate for their age, while thymectomized-irradiated-reconstituted rats and thymectomized rats had significantly more new bone and larger bone marrow space than the controls. In non-thymectomized, irradiated and reconstituted rats, bone induction occurred in only 25% of the animals, compared to 95% in other groups.     

New bone induction by demineralized bone matrix in immunosuppressed rats

Subcutaneous implantation of demineralized bone matrix (DBM) initiates a sequence of developmental events which culminate in endochondral bone formation. To test the effects of T-cell deficiency on new bone formation, the morphology of DBM-induced bone was examined in rats thymectomized at three weeks of age and in thymectomized or nonthymectomized rats lethally irradiated and reconstituted with syngeneic bone marrow. At 24 days after implantation, bone induction in control rats was appropriate for their age, while thymectomized-irradiated-reconstituted rats and thymectomized rats had significantly more new bone and larger bone marrow space than the controls. In non-thymectomized, irradiated and reconstituted rats, bone induction occurred in only 25% of the animals, compared to 95% in other groups.     

Effect of pretreatment with acetylsalicylate on surgical bleeding and peroperative mortality in rats undergoing kidney transplantation.

42 rats were pretreated with L-ASA before kidney transplantation, 43 rats acted as controls. 9 rats with L-ASA, but no control rats, died with i.p. haemorrhage. However, in animals surviving the operation, the intraoperative blood loss did not differ significantly between the 2 groups.     

Changes with hypertension and maturation in the response of stomach fundus to acetylcholine

The purpose of these experiments was to compare the contractile response to ACh of stomach fundal strips from hypertensive (SHR) and normotensive (WKY) rats during the development of hypertension. The results indicate that the reactivity to ACh is the same in fundal strips from young SHR and WKY rats; however, with maturation strips from WKY rats undergo a reduction in responsiveness which does not occur in the SHR. Therefore, strips from older SHR rats are more reactive to ACh than are those from age matched WKY rats.     

Effects of adrenal demedullation combined with chemical sympathectomy on cold-induced responses of endocrine pancreas in rats

Adrenal demedullation combined with chemical sympathectomy with 6-hydroxydopamine (ACS) lowered plasma glucagon and insulin levels in rats. Acute cold exposure increased plasma glucagon in both ACS and control rats, while it increased plasma insulin only in ACS rats. ACS rats responded to cold with a smaller increase in plasma glycerol and a more pronounced elevation of plasma free fatty acids.     

Age-related response of citrate synthase to hydrocortisone in the liver and brain of male rats

The activity of citrate synthase of the liver and brain of rats shows a gradual increase as a function of age. Adrenalectomy causes no significant change in the activity of citrate synthase in either of these tissues in young, adult or old rats. Administration of hydrocortisone to adrenalectomized rats depresses the activity of this enzyme maximally in the liver and brain of young rats. Administration of actinomycin D tends to normalize the depressed level of this enzyme.     

Vascular reactivity in chronic Goldblatt two kidney-one clip hypertensive rats

We studied the possible contribution of increased vascular reactivity in the chronic phase of Goldblatt two kidney-one clip hypertension. Vascular reactivity was evaluated in aortic strips from hypertensive rats (16 weeks after inducing hypertension) and age-matched control rats. The findings were: a) increased sensitivity to vasopressin in the aortic tissue of hypertensive rats, b) a similar response to angiotensin II, noradrenaline and KCl in hypertensive and control rats, and c) reduced maximal response to angiotensin II compared with other vasoconstrictors in both groups of rats. These results suggest a possible role for vasopressin in the chronic phase of this model of hypertension.     

Is the basal activity of rat stomach histidine decarboxylase affected by antrectomy?

The serum gastrin concentration and the gastric histidine decarboxylase activity are high in freely fed, unoperated rats but low in antrectomized rats. Following food deprivation the serum gastrin level and the enzyme activity are reduced simultaneously in the unoperated rats. After fasting for 36-48 h - but not before - the enzyme activity drops to the same low levels as in antrectomized rats.     

Effect of pretreatment with acetylsalicylate on surgical bleeding and peroperative mortality in rats undergoing kidney transplantation

Summary 42 rats were pretreated with L-ASA before kidney transplantation, 43 rats acted as controls. 9 rats with L-ASA. but no control rats, died with i.p. haemorrhage. However, in animals surviving the operation, the intraoperative blood loss did not differ significantly between the 2 groups.     

Increase of collagen synthesis in pulmonary arteries of monocrotaline-treated rats

Collagen synthesis in the pulmonary artery in animals with pulmonary hypertension was studied using monocrotaline-treated rats as a model. Incorporation of 14C-lateled proline into collagenase-digestible protein in the pulmonary artery was found to be 4-5 times higher in monocrotaline-treated rats than in control rats.     

Hypothalamo-hypophyseal-gonadal function in the rat following administration of the novel and selective D-1 agonist CY 208-243

The effects of the novel and selective dopamine D-1 agonist CY 208-243 on the rat hypothalamo-hypophyseal-gonadal (HHG) axis were studied. CY 208-243 did not modify the concentration of luteinizing hormone (LH) in serum from female or male rats, and had no effect upon opiate antagonist-induced stimulation of LH secretion in male rats. CY 208-243 did not inhibit ovulation in cycling female rats. Thus, D-1 receptor activation by systemic drug administration does not alter HHG function in rats.     

Long-term depressor effects of catecholamine neuronal grafts in the third ventricle of the brain in normotensive rats

Neuronal tissue containing A-6 group noradrenalin (NA) neurons of the locus ceruleus, or A-10 group dopamine (DA) neurons of the substantia nigra, was grafted into the third ventricle at the level of the preoptic-anterior hypothalamic region, in normotensive male rats. A significant and long-lasting depressor effect was shown in rats with either graft. In rats with an NA neuron-rich graft, plasma concentrations of arginine-vasopressin (AVP), plasma renin activity (PRA), and corticosterone (CS) decreased significantly, whereas in rats with a DA neuron-rich graft, AVP and PRA concentrations also decreased significantly but CS showed no significant change. Neither NA nor adrenalin in plasma changed significantly in rats with either graft.     

Vascular reactivity in chronic Goldblatt two kidney-one clip hypertensive rats

Summary We studied the possible contribution of increased vascular reactivity in the chronic phase of Goldblatt two kidney-one clip hypertension. Vascular reactivity was evaluated in aortic strips from hypertensive rats (16 weeks after inducing hypertension) and age-matched control rats. The findings were: a) increased sensitivity to vasopressin in the aortic tissue of hypertensive rats, b) a similar response to angiotensin II, noradrenaline and KCl in hypertensive and control rats, and c) reduced maximal response to angiotensin II compared with other vasoconstrictors in both groups of rats. These results suggest a possible role for vasopressin in the chronic phase of this model of hypertension.The authors thank Ms Karen Shashok for revising the English style.     

Effects of sham-pinealectomy,performed under white and red light,on the melatonin content of rat pineal glands

Summary Sham-pinealectomy, performed under different light conditions in newborn and adult rats, is followed by changes of pineal activity resulting in variations of melatonin content. The pineal glands of rats sham-operated under white light produce significantly less melatonin. In contrast, glands of rats operated on under red light show a melatonin content corresponding to that of intact rats. This result implies that normal white light causes a disturbance in melatonin production by a non-retinal pathway.     

Copper metabolism in the LEC rat: Involvement of induction of metallothionein and disposition of zinc and iron

The Cu concentration was about 40 times higher in the liver of LEC (Long-Evans with a cinnamon-like coat color) rats aged 77 days (227.5±21.6 g/g liver) than in Fischer rats (5.2±0.1 g/g liver). However, in the kidney and brain of the LEC rats, Cu concentrations were lower than in these organs of the Fischer rats. Cu concentration in the hepatic metallothionein fraction was about 130 times higher in the LEC rats than in the Fischer rats. The LEC rats showed markedly low concentrations of Cu in the serum and bile. It seems likely that excretion of Cu from the liver into the bile and blood (as ceruloplasmin) is inherently lacking in the LEC rat.     

Decreased number of asialoglycoprotein receptors in diabetic BB Wistar rat

The binding of asialoglycoproteins by hepatic binding protein was studied in freshly isolated hepatocytes from genetically diabetic BB Wistar rats. The number of cell surface asialoglycoprotein receptors was dramatically decreased (58,000 +/- 38,000 for diabetic rats compared to 267,000 +/- 70,000 for normal rats), while the association equilibrium constant was not changed. These results parallel those obtained with streptozotocin-diabetic rats and support the hypothesis that insulin deprivation is responsible for the decrease in the receptor number.