Ability of the opiate kappa-agonist bremazocine to facilitate the flexor reflex of the right hindlimb in spinal rats

It has been found that bremazocine predominantly enhances the flexor reflex of the right hind limb, without affecting the left limb. The similarity of the visual data measuring the asymmetry of the pose and the asymmetry of EMG responses to painful stimulation has a high probability. No correlation between the asymmetry of the pose and EMG extensor activity has been found.     

Inhibition of the development of adjuvant arthritis in rats as affected by vitamin E

The experiments on rats have shown that preliminary oral administration of vitamin E significantly suppressed generalization, but not development of adjuvant-induced arthritis. Oral vitamin E administration beginning one day after the onset of arthritis inhibited the development and generalization of the disease. Vitamin E had no effect on serum lysosomal enzyme activity, but markedly depressed lipid peroxidation.     

Demonstration of postural asymmetry factors in a hypophyseal tissue culture as affected by the cerebrospinal fluid of cats with unilateral damage to the hemispheric cortex

It has been experimentally established that special hypophysiotropic factors--precursors of pose asymmetry factors (PAF) are found in the cerebrospinal fluid of donor animals with cortical lesions during the first postoperative hours. These factors, being specific for the location of the cortical lesion in donor animals, appear to be hypophysiotropic peptide substances inducing the production of corresponding PAF by hypophysial cells. The production of certain PAF by the rat hypophysial tissue cultures under the influence of cerebrospinal fluid from cats gives evidence in favour of species nonspecificity of PAF inductors.     

Characteristics of the compensatory repair processes in the thyroid of 1-month-old rats as affected by sympathectomy

A considerable decrease in the amount of sympathetic nervous cells in neonatal rats injected guanethidine resulted in the depression of thyroid gland functional activity in 1-month-old animals, there was an apparent parallel increase in the proliferative activity of the gland. A 2/3 thyroidectomy led to the functional tension of the remaining part of the organ. A comparison of compensatory-reparative processes after thyroidectomy has shown similarity of reparative changes in experimental and control rats, however, the degree of repair potential was much higher in the sympathectomized thyroid gland.     

Characteristics of the granules formed in nucleated erythrocytes as affected by cardiotrast

Numerous granules are formed in frog erythrocytes under the influence of cardiotrast (C) (diethanolamine-3,5-diiodo-4-pyridone-1-acetic acid). However, as revealed by cytospectrophotometric investigation and X-ray microanalysis, no C was accumulated in these granules. It is known that C can dissociate into diethanolamine and 3,5-diiodo-4-pyridone-1-acetic acid. It was assumed that under the influence of C granule formation may occur at the expense of an uncharged diethanolamine form penetrating into lysosome-like structures to be accumulated by protonation process. Diethanolamine was found to provoke granule formation in frog erythrocytes. It is impossible to reveal substance in granules because it is colourless and has no ultraviolet absorbtion band. Under the influence of some inhibitors of energy metabolism on granule formation and the granules formed, their inhibitory effect is exerted on the process of granule formation. In granules isolated by differential centrifugation activity of some marker lysosomal enzymes was found which enabled us to attribute these granules to lysosome-like structures.     

Passive avoidance in amygdalectomized rats as affected by methylphenidate and midantan

It is shown that disturbance of conditioned reaction of passive avoidance in Wistar rats, elicited after bilateral amygdalectomy, may be compensated by administration of indirect dopamine agonist--methylphenidate. Two-fold administration proved to be effective: that before learning and that before testing. Two-fold administration of another dopamine agonist--amantadine did not restore the disturbed conditioned reaction. The results are discussed in the aspect of the role of different dopamine brain systems in passive avoidance and possible specificity of the drugs action.     

Release of immunoreactive met-enkephalin by intraventricular beta-endorphin in anesthetized rats

The release of immunoreactive met-enkephalin and leu-enkephalin from the spinal cord by intraventricular injection of different doses of beta-endorphin was studied using the intrathecal perfusion technique. The intraventricular beta-endorphin elicited the release of immunoreactive met-enkephalin from the spinal cord in a dose dependent manner. Immunoreactive leu-enkephalin in the spinal perfusate was not increased after intraventricular beta-endorphin injection. Both immunoreactive met-enkephalin and leu-enkephalin in the spinal cord were not changed by low doses (2-6 micrograms) of beta-endorphin but were increased markedly by 60-70% after high doses of beta-endorphin (32-64 micrograms). It is likely that the biosynthesis of enkephalins was also increased after intraventricular beta-endorphin injection. Intraventricular naloxone, 30 micrograms did not induce any release of immunoreactive met-enkephalin from the spinal cord and did not block the release of immunoreactive met-enkephalin induced by intraventricular beta-endorphin, 15 micrograms.     

Effects of endogenous opioids on the development of reproductive function in rats]

The influence of opioid peptide on the process of formation of reproductive function in rats was studied. Administration of beta-endorphin to neonatal female rats did not affect the concentrations of oestrogen and androgen receptors in the hypothalamus and pituitary, whereas the content of testosterone receptors was significantly higher in both hypothalamus and pituitary. Chronic administration of beta-endorphin to both female and male rats does not affect the concentration of sex hormones. The results obtained indicate that chronic administration of beta-endorphin to neonatal female rats lead to formation of instable contacts in the mechanism of regulation of hypophysis gonadotropic function.     

Opioids evoke postural asymmetry in rats: the side of the flexed paw depends on the type of opioid agonist

Opioid kappa-agonists bremazocine and dynorphin (1-13), sigma-agonist SKF 10.047 and delta-agonist D-Ala2, D-Leu5-enkephalin (DADL) induce postural asymmetry of rats hind limbs under subarachnoidal administration below the level of spinal cord section (T3-T4). The side of the flexed leg depends on the opioid agonist type: bremazocine and dynorphin (1-13) induce predominantly right flexion. SKF 10.047--the left flexion, but not in all doses, DADL--in small doses (1 and 100 pg per animal)--of the right one, in larger doses (up to 10 ng per animal)--of the left one. Saline and opiate mu-agonist morphine do not induce postural asymmetry. Opiate antagonist naloxone prevents asymmetry development when injected prior opioid agonists, and also decreases the number of asymmetries induced by these agonists. Naloxone alone does not influence the per cent of animals with pose asymmetry. The opioid receptors are involved in asymmetry development. The revealed ability of opioid kappa-, delta- and sigma-agonists may be based on lateralization of opioid receptors in the rat spinal cord.     

Axillary bud development of passionfruit as affected by ethylene precursor and inhibitors

Summary The effects of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) and two inhibitors, silver thiosulfate (STS) and aminoethoxyvinylglycine (AVG), were tested in yellow passionfruit (Passiflora edulis f. flaricarpa Degener) acillary cultured in vitro. The organogenic responses were assessed by the number of buds per explant, mean leaf area per explant, and shoot length. ACC-supplemented medium significantly inhibited all evaluated responses at both concentrations tested. When ethylene action and biosynthesis were inhibited, a significant increase in the number of developed buds and average leaf area was observed. Accumulated ethylene and its accumulation rate were significantly greater at 10 μM ACC, with a maximum production rate deteeted: at the 14th day and a decline at the 21st day. The results suggest beneficial effects of ethylene inhibitors on in vitro development of axillary buds and their reliability for use as an alternative approach to evaluate sensitivity of Passiflora species to ethylene. Even though shoot elongation did not differ from that of the control, the inhibition of the ethylene action and its biosynthesis by AVG and STS, respectively, significantly enhanced the number of buds per explant and leaf area.     

Growth and development ofRumex roots as affected by hypoxic and anoxic conditions

The growth characteristics of threeRumex species were determined under different solution oxygen concentrations in hydroculture. These species all occur in a river foreland ecosystem and they were found to differ in their flood tolerance. The flood-tolerantR. maritimus undR. crispus developed a large number of new, aerenchymatous roots within a short period under low solution oxygen concentrations. Biomass production was not affected. In the flood-intolerantR. thyrsiflorus, however, only few slow-growing new roots were developed and biomass production was significantly reduced at solution oxygen concentrations below 2% (v:v). These different responses could be partly explained by a differential aerenchyma formation in new roots of the flood-tolerant species. Aerenchyma can relieve the oxygen stress of the root systems via internal aeration.The fast development of new roots of the flood-tolerantR. maritimus andR. crispus after the onset of anaerobiosis coincided with the reduction or cessation of growth of the primary roots. Notwithstanding the cessation of growth, however, primary roots of both species were able to recover following restoration of aerobic conditions after a 13-day anaerobic period. However, the roots ofR. thyrsiflorus ceased growing very soon after the onset of anaerobiosis. All had died within 10 days.The balance between the growth rates of the primary and the newly formed root system are discussed and related to the differential tolerance of theRumex species to transient flooding.     

Inactivation of the postural asymmetry factor at the stage of compensation for the postural disorder induced by unilateral removal of the motor area

The peptide nature of the posture asymmetry factor (PAF) produced in the brain after unilateral removal of the motor region of the neocortex was established. The inactivation of PAF activity in the brain toward the end of the third week after the removal is due to PAF inactivation by the endogenous factor absent from the intact brain. The molecular weight of the inactivation factor exceeds 5.0 kD that makes it possible to separate it from the PAF by gel filtration on Sephadex G-25. The correlation was marked between the increasing activity of the PAF inactivation factor and the recovery of the initial symmetric functioning of the spinal centers during three weeks after unilateral damage to the CNS.     

Decreased acetylcholinesterase activity in the area of epileptogenic foci created by met-enkephalin in the hippocampus of rats

Experiments on rats with electrochemotrodes implanted in the left and right hippocamp have shown that in epileptogenic foci created by microinjections of met-enkephalin or D-ala-2-met-enkephalin into the hippocamp, acetylcholinesterase activity (AChE) was diminished. It is assumed that reduction in AChE activity is an adaptive mechanism by which the excitability of hippocampal inhibitory basket cells, which are sensitive to acetylcholine, is increased.     

Analgesic activity of substance P in rats: apparent mediation by met-enkephalin release

The intracerebroventricular administration of Substance P (SP) produced a marked and short-lasting increase in the threshold for vocalization and vocalization afterdischarge in the rat after electrical stimulation of the tail. This effect was blocked by naloxone and potentiated by bacitracin, a peptidase inhibitor. The analgesic effect of SP was also blocked by the concomitant intraventricular injection of the specific antibody against the opioid peptide metenkephalin but not by the antibody against beta-endorphin. Anti-met-enkephalin did not block other pharmacological actions of SP. The results suggest that SP produces an analgesic effect in rats by releasing met-enkephalin at supra-spinal levels involved in pain control.     

Lipoprotein status in Sprague-Dawley and LA/N-corpulent rats as affected by dietary carbohydrates.

1. To compare the impact of type of carbohydrate, genotype and phenotype on the synthesis and levels of plasma lipoprotein protein. Sprague-Dawley rats and carbohydrate-sensitive LA/N-corpulent (cp) rats were fasted (2 days) and then fed diets containing 54% carbohydrate as either sucrose, fructose or cooked cornstarch for 2 days. 2. The amount of 3H-protein present in the VLDL + chylomicron fraction of Sprague-Dawley rats 2 hr after injection of 3H-leucine was affected by type of dietary carbohydrate: sucrose greater than fructose greater than starch. 3. Obese and lean LA/N-cp rats fed diets containing sucrose or fructose had lower concentrations of HDL protein and higher levels of 3H-protein in VLDL + chylomicron fraction than those fed starch. 4. Obese LA/N-cp rats had more HDL protein and higher levels of 3H-protein in VLDL + chylomicron fraction than their lean littermates.     

Forms of goal-directed behavior as affected by induced changes in the level of endogenous beta-endorphin in rats

Marked alterations in feeding and defense behaviour and motor activity partly resembling the effects of exogenous beta-endorphin administration were demonstrated in the experiments on rats. These alterations were observed after immunization with beta-endorphin--bovine serum albumin conjugate (two subcutaneous injections at a 7-day interval at a dose of 75 micrograms, 1 mole BSA/6 moles beta-endorphin mixed with complete Freund's adjuvant). A decrease in beta-endorphin content in some brain structures was noted. Unlike control animals, the immunized rats revealed within 3-4 weeks an increase in food intake without any rise in body weight and practically no response to handling.     

Postural asymmetry in rats induced by stress and pain stimuli

A significant number of rats (31–68%) subjected to pain stimulation (intraperitoneal injection of 1% or 5% acetic acid, 5 ml/kg), immobilization stress (6 hrs in a supine position) or cold stress (3 hrs at 4–6°C) exhibited postural asymmetry of hind limbs after spinal cord transection at T7 level. The number of rats with right and left limb flexions was approximately equal. Naloxone (2 mg/kg intraperitoneally) prevented the development of postural asymmetry induced by pain and stress stimuli. Postural asymmetry of hind limbs appears to be due to an asymmetric CNS response to stress and pain stimuli. Our data imply that endogenous opioid peptides and opiate receptors may be involved in the regulation of this response.     

Blood pressure of rats as affected by diet and concentration of NaCl in drinking water.

In the first experiment, weanling rats were fed a grain ration or one of three semipurified diets high in fat, sucrose, or cornstarch. Rats in each dietary group were divided into two subgroups, one of which drank distilled deionized water whereas the other group drank 2% NaCl solution. Blood pressure and sodium intake were individually measured for each rat at weekly intervals for a 10-week period. Rats receiving the salt solution had higher mean blood pressures (127-178 mmHg) than rats offered distilled water (108-127 mmHg). When drinking solutions were the same, more severe rises in blood pressure occurred in rats fed the semipurified diets than in those rats fed grain. In a second experiment, rats were fed one of the four diets used in the first experiment; however, they received a 1% NaCl drinking solution for 9 weeks followed by a 1.5% NaCl solution for an additional 9 weeks. At Week 18, pressures among these groups of rats ranged from 136-140 mmHg, regardless of diet.