The effect of malnutrition on placenta

Effect of malnutrition was studied on placentas of eighty-five malnourished mothers, taking the placentas of sixty-five well nourished mothers as control. Nutritional status of mothers were studied by estimation of haemoglobin, total R.B.C. count and serum protein. Mothers of the malnourished group, showed anaemia of normocytic, microcytic, a few macrocytic type and hypoproteinaemia. Their placentas were of lower weights and sizes than those of control group. Placentas of both the groups showed infarction, degenerative, calcification, fibrinoid necrosis of villi, intervillous fibrin deposition, villous fibrosis, syncytial knotting of villi and proliferation of Langhan's cell of the villi. But the extent and degree of these changes were much more in malnourished group than control group. Activities of the enzyme such as alkaline phosphatase and Glucose-6-phosphatase in placental villi were increased in malnourished group than those in control group. So it appears that placentas of malnourished mothers become underdeveloped having pathological changes greater in extent and degree than control group resulting in inadequate supply of nutrients from mother's blood to foetus blood.     

The effect of gastroduodenal xylocaine on the basal pancreatic secretion in rats

The effect of intragastric and intraduodenal xylocaine on the pancreatic secretion was investigated in conscious rats. A 1% xylocaine infusion strongly decreased pancreatic protein output and flow during recirculation of pancreatic juice into the duodenum, but it diminished only moderately the increase in the secretion seen after its diversion and after duodenal infusion of soybean trypsin inhibitor. Moderate inhibition appeared during prolonged diversion of pancreatic juice. The response to exogenous CCK + secretin was not modified. The results indicate that during recirculation of pancreatic juice, which is more physiologic than its diversion from the duodenum, the neural control may play a significant role.     

Cholecystokinin-induced satiety in weanling rats

Intraperitoneal injections fo the synthetic C-terminal octapeptide of cholecystokinin (CCK) into fasted 21-day-old weanling rats produced a significant suppression of intake of solid and liquid diets. Similar injections had no effect on water consumption of thirsty weanlings. The early appearance of CCK-induced satiety is consistent with the idea that this mechanism is responsible for the effectiveness of gastrointestinal factors in determining intake of very young rats.     

The effect of cholecystokinin octapeptide and glucagon (1-29) on food intake of weanling rats

Cholecystokinin octapeptide (CCK-8) and glucagon (GLG) decrease food intake of a number of species. However, the responsiveness of rats to the food intake effects of these peptides may develop differentially due to sex, age and/or developmental state. Male and female weanling rats decreased early dark cycle food intake following the administration of 5 and 10 micrograms/kg CCK-8 and male rats were more responsive than female rats, p less than 0.05. GLG did not decrease early dark cycle food intake of either male or female weanling rats. Weanling male rats increased plasma glucose and insulin levels in response to GLG administration, p less than 0.05. Male rats were retested with GLG (250 and 500 micrograms/kg) at 6, 9 and 22 weeks of age. GLG did not decrease food intake of these rats until they reached 9 weeks of age and they were still responsive at 22 weeks of age, p less than 0.05.     

Monokine secretion in aging and protein malnutrition

Aged and protein-malnourished hosts have diminished febrile responses and increased morbidity and mortality from infection that could be due to deficiencies in the production of certain monokines. In this study, the ability of peritoneal macrophages from aged and protein-malnourished rats to produce IL-1 and TNF was explored. Aged rats fed a standard diet produced less IL-1 and TNF, as measured by the thymocyte proliferation and L929 cytotoxicity assays, than young and middle-aged rats. Monokine production was not diminished by protein malnutrition in any age group. No synergistic decline in IL-1 or TNF production was seen with increasing age in malnourished rats. Diminished IL-1 and TNF production may partially explain the severity of infection seen in the elderly patient, but not the malnourished host. The role of other cytokines such as IL-6 and cytokine inhibitors in aging and malnutrition should be explored.     

Dose-dependent effect of carbamazepine on weanling rats submitted to subcutaneous injection of tityustoxin

The scorpion envenoming syndrome is a serious public health matter in Brazil. The most severe cases occur during childhood and elderly. Previous results from our laboratory suggest that the effects of scorpion toxins on the central nervous system play a major role on the lethality induced by scorpion envenoming. The aim of this work is to evaluate the therapeutic potential of carbamazepine (CBZ) injected i.p. 90 min before s.c. tityustoxin (TsTX) injection in weanling rats. Rats were divided into six experimental groups according to s.c. injection (saline or TsTX) and i.p. treatment (vehicle or CBZ 12, 50 and 100 mg/kg): Sal/Veh group (n = 4); Sal/CBZ100 (n = 4); TsTX/CBZ12 (n = 6); TsTX/CBZ50 (n = 8); TsTX/CBZ100 (n = 8) and, at last, TsTX/Veh (n = 8). The dose of TsTX was the same for all groups: 6.0 mg/kg, twice the DL50 for weanling rats. Video images were recorded until death or for a maximum period of 240 min. Lungs were excised and weighed to evaluate edema. The results showed that CBZ (12, 50 and 100 mg/kg) was able to increase the survival rate and latency-to-death of the rats. Only the group treated with 100 mg/kg of CBZ had a decrease in the pulmonary edema. The known effect of CBZ reducing neuronal excitability most likely protected the neural substrates targeted by TsTX. Although treatment was performed before TsTX inoculation, the results are promising regarding CBZ as a therapeutic coadjuvant in the treatment of scorpion poisoning. The pharmacokinetics of CBZ can be very much improved by either changing the form of administration or encapsulating the drug in order to enhance solubility.     

Stimulating effect of duodenal alkalinization on pancreatic exocrine secretion in rats

Intraduodenal instillations of 1.0 M NaHCO3, 0.1 M Na2CO3, and 0.1 M NaOH in anesthetized rats stimulated significantly the pancreatic exocrine secretion showing 3.8-, 7.1-, and 19.0-fold increase of the pancreatic juice flow, respectively. Protein concentration and amylase activity in pancreatic juice increased after injecting NaOH, but decreased after injecting Na2CO3.     

Passive Heymann nephritis in pre- and post-natal rats

Passive Heymann nephritis (PHN) was induced in pre- and post-natal rats by a single intra-peritoneal injection of 0.2 ml of a rabbit anti-rat kidney fraction 3 (rKF3) antibody. Immune complex formation occurred only in those glomeruli or parts of glomeruli which were open to the circulation. Double staining of kidney sections for the glomerular nephritogenic antigen and rabbit IgG, 2 days after the injection of the antibody showed an identical distribution of both components in the glomeruli. In rats killed more than 4 days after the injection of the anti-rKF3 antibody, the nephritogenic antigen could be demonstrated in the subcapsular glomeruli, in the absence of rabbit IgG; and the same applied when the kidneys had reached maturity. When the injected antibody was expected to be present in the circulation, no nephritogenic antigen was demonstrated in the glomeruli in the absence of the heterologous IgG. These observations indicate that the nephritogenic antigen appears in the glomerulus at the same time as the glomerular capillary loops open to the circulation. Unlike PHN in the adult rat, the immune complexes in the glomeruli of neonatal rats do not persist longer than 84 days.     

Histamine-elicited drinking in weanling and adult rats

A total of 260 male and female adult (60-70 days of age) and weanling (22-25 days of age) Sprague-Dawley derived rats were used in these experiments. Subcutaneous administration of histamine (HA) elicited drinking in a dose-dependent manner for both ages tested, although the threshold dose varied with age. A dose of 5.0 mg/kg HA elicited significant increases in water intake for adults, whereas for weanlings a dose of 20 mg/kg HA was necessary. Adult rats exhibited decreased latency to drink after all doses of HA tested, whereas for weanlings, decreased latency was evident only after doses of HA sufficient to elicit increases in water intake. Combined antagonism of H1 and H2 receptors for HA, using dexbrompheniramine and cimetidine, respectively, inhibited HA-elicited drinking in adults and weanlings. Further investigation of the ontogeny of histamine- and food-related drinking may provide a useful approach to examine the physiological mechanisms underlying fluid consumption in adult animals and as they are gradually elaborated during ontogeny.     

Odor preferences in neonatal and weanling rats

In order to establish odors which can be used in appetitive and aversive conditioning paradigms, naive rat pups, postnatal day 7 (i.e., PND 7) and weanlings (PND 25), were placed in a rectangular open field with an odorant at one or both ends. Time spent over each odor was measured for 3 min. At both ages subjects avoided peppermint, orange, and lemon odors in favor of fresh home-cage bedding. Comparing any of these three odorants with each other resulted in no significant differences in preferences. In experiments using banana odorant, equal time was spent between banana and no odorant. However, in a two-odorant choice between banana and peppermint, weanlings preferred banana whereas pups showed no preference. The results of this study indicate that in an appetitive learning paradigm, peppermint, orange, or lemon odors may be used, while in aversive learning paradigms banana odor may be more appropriate for weanlings. © 1998 John Wiley & Sons, Inc. Dev Psychobiol 33: 157–162, 1998     

The short term effect of peripherally administered brain-gut peptides on gastric acid secretion in rats

Certain brain gut-peptides are known to either stimulate or inhibit gastric acid secretion in several species after direct injection into the central nervous system. However there is inconsistency of published results on the gastric acid secretory response to some of these peptides after peripheral administration in different experimental systems. Seven peptides, namely neurotensin (NT), substance P, cholecystokinin (CCK), thyrotropin releasing hormone (TRH), human calcitonin (hCT), rat calcitonin-gene-related peptide (rCGRP) and bombesin, all known to modulate gastric acid secretion after central administration, were initially screened for activity after peripheral (subcutaneous) injection of 10 g/kg body weight in a single rat model. Peptides showing an effect were retested at lower doses. Despite the inherent variability of the gastric acid secretory response in the non-anaesthetized pylorus ligated rat, a standardized experimental design confirmed that reproducible and statistically valid results could be obtained. The technical feasibility of using a one hour collection period as might be appropriate for short acting peptides was demonstrated by the significant dose dependent inhibitory activity of salmon calcitonin. In this model, NT and substance P had no significant effect on either volume or concentration of acid secreted, CCK showed a slight stimulation of acid output, and TRH, hCT, rCGRP and bombesin all inhibited acid output; CGRP and bombesin were active at 10 and 100-fold lower doses. The potent and inhibitory activity of bombesin in this system is in disagreement with other publications reporting no effect or variable stimulatory effect in rats. Time and dose dependent responses in our rat system indicate that this apparent discrepancy may be explained by the short duration of action of bombesin.     

The effects of arginine deficiency on the water and solute metabolism in weanling rats

1. Weanling rats fed on a synthetic diet, which was completely deficient in arginine, grew more slowly than rats fed on a similar diet which included arginine.

2. No differences in the haemoglobin level or plasma protein concentration or electrophoretic pattern were found in the two groups of rats.

3. The arginine-deficient rats drank less water, and excreted less urine, which was more concentrated than that of the control animals, although the solute output was reduced, and the extrarenal water losses were the same.

4. The arginine-deficient animals excreted less urea, non-protein nitrogen, creatinine and total solutes. The blood urea concentration of the deficient animals was significantly higher than that of the controls, indicating that arginine deficiency had impaired the excretion of urea.

5. There was no difference between the renal weights of both groups of animals when related to total body weight, nor was there a difference in the histological appearance of the kidneys.

6. The amounts of arginine vasopression and oxytocin/kg body wt. stored in the neurohypophyses of both arginine-deficient and control animals were the same.