I. A. Gomez De Segura

Enriched protein diet-modified ghrelin expression and secretion in rats

Gastrointestinal (GI) integrity and function are regulated by nutrition and growth factors. The discovery of ghrelin, a natural growth hormone (GH) secretagogue produced by the gastrointestinal (GI) tract, is a potential link between diet and growth signals. The aim of this study was to evaluate macronutrient effect on ghrelin expression and secretion in addition to some possible function in intestinal trophic status. Wistar rats were fed a high-carbohydrate, high-protein (HP), high-fat or standard (St) diet. Animals received the same daily food volume and caloric intake. After 7 days, animals were fasted for 24 h and blood and tissue samples were obtained just before feeding or at 2 or 6 h after feeding. Fasting high-protein-fed rats had higher ghrelin plasma levels than with rats fed the high-carbohydrate, high-fat or standard diets. Two-hours after refeeding, ghrelin plasma levels had decreased in all groups with a slight recovery at 6 h after refeeding, except in the high-protein group. Ghrelin plasma levels in rats fed with the high-protein diet correlated negatively with their GH and insulin-like growth factor 1 (IGF-1) plasma concentrations which were also the lowest among the study groups. In conclusion, ghrelin secretion was nutritionally manipulated because a protein-enriched diet increased its levels.

Reduction of isoflurane MAC with buprenorphine and morphine in rats

Preoperative analgesics are being increasingly used to provide analgesia in the intraoperative and postoperative period. Opioids reduce anaesthetic requirements, although the effect varies with the different drug and species. The aim of this work was to determine whether buprenorphine reduces the minimum alveolar concentration (MAC) of isoflurane in a dose-related fashion, and whether this effect is similar to morphine when clinical doses of both drugs are used in the rat. Thirty-six male Wistar rats were anaesthetized with isoflurane, and MAC was determined before and after the administration of either buprenorphine or morphine. MAC of isoflurane was determined from alveolar gas samples when a standard noxious stimulus, in the form of a tail clamp, was applied. The duration and degree of reduction of the MAC of isoflurane were recorded. Basic cardiovascular and respiratory measurements were also recorded. Buprenorphine (10, 30 and 100 μg/kg) and morphine (1, 3 and 10 mg/kg) reduced in a dose-dependent fashion the MAC of isoflurane by 15%, 30% and 50%, respectively. Buprenorphine resulted in less cardiovascular and respiratory depression and had a longer-lasting action than morphine. In conclusion, buprenorphine has a dose-related isoflurane sparing effect in the rat similar to that caused by morphine at clinical doses of both drugs.

Chronic nicotine administration increases NGF-like immunoreactivity in frontoparietal cerebral cortex

Nicotine/nicotine agonists, which have been proposed as therapeutic agents for the treatment of Alzheimers disease and other neurodegenerative disorders, produce a wide variety of effects on the nervous system. Some mechanisms involved remain poorly understood. In this work, immunohistochemical techniques were used to determine the effect of nicotine on nerve growth factor (NGF) in the frontoparietal (motor, somatosensory) brain cortex of the albino rat. Nicotine was chronically administered intraperitoneally using osmotic pumps (0.35 mg nicotine base/kg body weight/day for 14 days). An increase in the number and the immunoreaction intensity of NGF‐like positive pyramidal and nonpyramidal neurons of these cortical areas was observed after treatment. Immunopositive astroglial cells were always seen in sections of treated animals but not in controls. The neuropil of control animals was, in general, devoid of reaction, but in treated animals, immunopositive prolongations were located randomly, some in close association with capillaries. At the electron microscopic level, these prolongations were demonstrated as belonging to neurons (dendrites and axons) and astroglial cells. Nicotinic activation of selected neurons and glial cells seems to trigger NGF/neurotrophic mechanisms, suggesting their use may be of benefit in prevention and treatment of neurodegenerative diseases.

Consequences of frozen storage for nutritional value of hake / Consecuencias del almacenamiento en congelación en el valor nutricional de merluza

Differences between fresh and frozen hake muscle in which proteins were highly aggregated during frozen storage, and their relationship with nutritional quality are evaluated. The differences between fresh and frozen muscle proteins were studied on the basis of protein solubility, type and state of muscle aggregation and amino acid composition. Nutritional value was determined by nitrogen bal ance and amino acid composition in the blood. The high level of aggregation in the frozen muscle was due mainly to disulfide and other covalent bonds. Lysine diminished in frozen muscle and in plasma. Although in frozen fish muscle, proteins were highly aggregated even by disulfide and non- disulfide covalent bonds, nitrogen balance in fresh and frozen fish was similar.

Somatostatin antagonism prevents elemental diet-induced intestinal atrophy in the rat

Somatostatin is a peptide with known antiproliferative effects on the intestine. The aim of the present work was to determine whether somatostatin (SST) antagonism reduces elemental diet-induced intestinal atrophy in the rat. Male Wistar rats were fed a standard diet and treated for seven days with either continuous infusion of saline or low and high doses of a putative somatostatin antagonist; another group was given a SST antagonist in a pulsatile high dose. All these groups received an elemental diet to induce gut mucosa atrophy. Rats were killed and samples were obtained for morphometric and proliferative measurements of the intestine and for SST and insulin-like growth factor-1 (IGF-1) level determination. The elemental diet decreased mucosal length and proliferation. Pulsatile administration of SST antagonist improved or prevented both effects, whereas continuous SST antagonist delivery prevented decreased crypt proliferation induced by the elemental diet. Somatostatin plasma levels were lowest in rats receiving pulsatile administration of SST antagonist. In conclusion, somatostatin antagonism increases proliferation in the intestinal mucosa, improving elemental diet-induced intestinal atrophy; however, morphological growth is not affected.

Electrophysiologic cardiac effects of the new local anesthetic IQB-9302 and of bupivacaine in the anesthetised dog

Background:  Local anesthetics are not free from potentially fatal complications. Therefore every new local anesthetic should be tested to demonstrate a lower, or at least similar, degree of toxicity over clinically used analogs. Most toxic effects from local anesthetics affect the cardiac electrophysiologic function, so the aim of this study was to characterize the electrophysiologic effects of a new long‐acting local anesthetic (IQB‐9302, Ciprocaine), and compare them with those of bupivacaine in the anesthetized dog.

Growth hormone effects in intestinal adaptation after massive bowel resection in the suckling rat

Background Massive small bowel resection provokes intestinal malabsorption that leads to diminished growth in the suckling rat. Growth hormone is one of the several factors that can enhance the adaptive response of the intestines in the adult rat; however, whether it also enhances postresection intestinal adaptation in the suckling rat, thus reducing the adverse effects of resection on growth, is still unclear. Methods Seventy-four 30-day-old suckling Wistar rats underwent 80% midgut bowel resection, laparotomy (sham operation), or no surgery. They were treated with either growth hormone or saline for 15 days and studied 15 or 45 days after surgery. Body weight was monitored and samples of bone and intestinal mucosa were obtained at the end of the study period for analysis. Results Resected rats lost body and bone weight regardless of growth hormone administration. Bowel resection provoked significant increases in the proliferation and size of the intestinal mucosa. Growth hormone significantly, but just barely, increased crypt height and mucosal mass at day 15 after surgery, but not at day 45. Lengthening of the intestines was the main effect of growth hormone. Conclusions The relatively small adaptive response of intestines to growth hormone is insufficient to promote body growth after intestinal resection in the suckling rat. This response is lower than that in older rats and may reflect an age-related differential response to growth hormone.

Effects of exogenous neurotensin on intestinal postresectional growth in the suckling rat

BACKGROUND In the suckling rat, massive bowel resection provokes intestinal malabsorption that leads to diminished growth. The object of this report was to test whether neurotensin, intestinal trophic peptide, enhances postresection intestinal adaptation, improving absorption and reducing the adverse effects of resection on growth. METHODS Fifty-seven 15-day-old suckling. Wistar rats were divided into four groups: 41 rats were subjected to resection of 90% of their small bowel, while the rest (n = 16) underwent laparotomy. Half of the animals, resected and laparotomized, were treated with neurotensin for 30 days. The body weight was monitored, and samples of bone and intestinal mucosa were obtained at the end of the study period for analysis. Blood was tested to determine iron, ferritin, folic acid, and vitamin B12 levels. RESULTS The resected animals lost body weight regardless of neurotensin administration. In the resected animals, femur weight increased significantly when they received neurotensin. Bowel resection provokes significant increases in the intestinal mucosa (crypts and villi), but after neurotensin administration, significant increases were detected only in the jejunum of the resected animals but not in the ileum of laparotomized rats. In the resected animals, significant decreases in iron, ferritin, folic acid, and vitamin B12 levels were observed. The postresection administration of neurotensin only produced a significant rise in the ferritin concentration. CONCLUSIONS In the suckling rat, neurotensin enhances the intestinal proliferative phenomenon but does not improve the course of medium-term postresection growth.

Synaptic immunolocalization of glyoxylate-complex molecules in the striate areas of the rat cerebral cortex: Light and electron microscopic studies

The location of glyoxylate‐complex molecules has been investigated in several areas of the rat cerebral cortex using the immunohistochemical peroxidase‐antiperoxidase (PAP) method. Antibodies against glyoxylate‐complex molecules have been developed in the rabbit after immunization with a glyoxylate‐bovine serum albumin conjugate. Observations carried out with the light microscope demonstrated positive immunostaining at the membrane level of scattered neurons located in all cortical areas, mainly in cortical layer IV. The striate areas (17, 18, 18a) had both the greatest number of immunopositive neurons and the most intense ones. At the electron microscopic level, it was observed that in the striate areas an immunopositive reaction was located mainly in the periphery of synaptic vesicles of some nerve endings, and in both pre‐ and postsynaptic membranes of these synaptic structures. The presence of glyoxylic acid and glyoxylate‐complex molecules in such areas leads us to suggest that these substances could play an important role in selected synaptic contacts in which some pyramidal and non‐pyramidal neurons are involved. J. Neurosci. Res. 51:268–274, 1998.