Biomedical subjects

Z J Yang

Publications and source records attributed to Z J Yang.

13 recordsLinked to original sources

PubMed1992

Influence of anterior subdiaphragmatic vagotomy and TPN on rat feeding behavior.

Total parenteral nutrition (TPN) inhibits food intake and feeding behavior. Whether caloric sensory function of the liver contributes to this food intake and feeding behavior regulation via vagal-afferent innervation was tested after performing anterior hepatic vagotomy or sham operation in rats infused with a TPN solution providing 100% of daily energy needs, given continuously for 4 days. Food intake, meal number, size, duration, meal and intermeal sniffs, and eating activity were measured using an automated computerized rat eater meter (ACREM). TPN infusion resulted in a significant decrease of food intake and feeding indexes in both groups. The vagotomized rats showed a significantly higher food consumption, achieved by greater meal frequency, larger meal size, and longer meal duration. Thus, vagotomized rats consumed more than their controls by eating larger meals more often and of longer duration. Data suggest that anterior hepatic vagotomy interrupts hepatic caloric sensory feedback loop, diminishing inhibitory vagal effects on food intake with TPN, leading to an overall increase in food intake.

Afferent Pathways↗

PubMed1992

Nocturnal cyclic versus continuous total parenteral nutrition: food intake and feeding pattern in rats.

Total parenteral nutrition (TPN), providing the equivalent of 100% of mean daily oral intake for 24 hours, depressed spontaneous food intake (SFI) in rats by a mean greater than 80%. Whether TPN had the same effect on SFI when given either in 12-hour cycles (Cyclic-TPN) or in 24 hours (Continuous-TPN) for 8 days was tested in 16 rats with jugular catheters, placed in metabolic cages modified with an Automated Computerized Rat Eater Meter. This continuously measures food intake and its dependent indexes: meal number, meal size, meal duration, meal sniffs and intermeal sniffs. Both rat groups ate the same amounts of chow before TPN. On starting TPN, food intake decreased by greater than 80% in Cyclic-TPN and greater than 50% in Continuous-TPN during each first infusion period. A nadir in food intake was reached in 48 hours with Cyclic-TPN and in 72 hours with Continuous-TPN. Thereafter, there was no food intake during the 12 hours of Cyclic-TPN, with minimal food intake during the intervening 12 hours of non-TPN normal saline infusion period. In both forms of TPN infusion, a reduction in food intake was achieved by a reduction in meal number and size, and thus in meal duration. Feeding-related sniffing activity was decreased by similar amounts with Cyclic- or Continuous-TPN. Cyclic-TPN for 12 hours had no advantage over Continuous-TPN, in that there was no compensatory enhancement of food intake and meal-related behavior during the cyclic non-TPN normal saline period.

Animals↗

PubMed1992

The comparative effects of abrupt vs. stepwise discontinuation of TPN in rats.

The comparative effects of discontinuing total parenteral nutrition (TPN: caloric ratio of glucose:fat:amino acid = 50:30:20) abruptly or in a stepwise manner on spontaneous food intake were investigated in two studies. Study 1: In 16 rats, TPN was given for 4 days, then stopped abruptly in eight rats. In the other eight rats, TPN was tapered; they received TPN at 75%, 50%, and 25% of their mean daily energy requirements per day for 3 consecutive days, and then switched to normal saline. Total parenteral nutrition induced a significant 60% reduction in spontaneous food intake (SFI) in both groups during the first TPN day. After 4 days of TPN, an 80% decrease in SFI had occurred in both groups. Resumption of SFI was significantly sooner in the abruptly-stopping group than in the stepwise-stopping group. But, in the latter group, there was a significantly greater cumulative caloric intake during the entire study. Study 2: In 32 rats, TPN providing either 100%, 50%, or 25% of their mean daily caloric requirements was given to three groups each of eight rats, for 3 days, then abruptly changed to normal saline; control rats received normal saline throughout. The TPN-induced decrease in SFI was proportional to the caloric density of the solution infused. Three days of 100%, 50%, or 25% TPN infusion led to an approximate 85%, 60%, or 35% decrease in SFI, respectively. Spontaneous food intake recovery was independent of the caloric density of TPN.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Dynamics of oral intake resumption after general anesthesia and operation in rats.

The influence of general anesthesia and operation on dynamics of postoperative food intake resumption was investigated in eight rats. A laparotomy was performed on each rat under anesthesia induced by intraperitoneally injected chloral hydrate. Spontaneous food intake and feeding indexes were continuously measured using an Automated Computerized Rat Eater Meter (ACREM) before and after operation. Although spontaneous food intake and all feeding indexes were depressed immediately following anesthesia and operation, each feeding index was depressed to a greater degree during the dark vs. the light cycle. Initially, rats fully capable of eating ate fewer, smaller, and shorter meals. The return to normal of each feeding index differed temporally. Thus, although meal number normalized by the third postoperative day, meal size by the sixth postoperative day, and meal duration by the fourth postoperative day, normalization of meal number during the light cycle occurred sooner than during the dark cycle, while the converse occurred with meal size and meal duration.

Anesthesia, General↗

PubMed1991

Muscarinic receptors and parasympathetic neurotransmission in guinea-pig trachea.

Muscarinic receptors involved in cholinergic neurotransmission were studied in isolated innervated guinea-pig tracheas using preganglionic (nerve) and postganglionic (field) stimulation, after blocking sympathetic effects with bethanidine (5 microM). Neostigmine (10 nM) significantly increased responses to nerve and field stimulation. The M1 antagonist pirenzepine (0.1-100 nM) selectively reduced tracheal responses to nerve stimulation in control and in neostigmine-treated tissues. The M2 antagonist gallamine (0.1-100 microM) significantly increased tracheal responses to nerve and field stimulation in control and in neostigmine-treated preparations. At concentrations that increased baseline tone, oxotremorine, arecoline and pilocarpine decreased responses to nerve and field stimulation. Gallamine (30 microM) selectively reduced the inhibitory effects of these agonists on responses to nerve and field stimulation. The findings indicate that cholinergic neurotransmission in guinea-pig trachea is modulated by facilitatory M1 receptors at parasympathetic ganglia and inhibitory M2 receptors at the postganglionic nerve endings.

Animals↗

PubMed1991

Change in meal size, number and duration after neural isolation of liver and with TPN.

The abundant neural connections between the liver and hypothalamus suggest that the liver contributes to spontaneous food intake (SFI) regulation. This hypothesis was tested in rats after total liver denervation (TLD) and infusing TPN. A sham operation (SO) or TLD was performed in Fischer rats, placed in metabolic cages fitted with an Eater Meter to measure SFI, meal number (MN), size (MZ), and duration (MD). Rats had free access to chow and water. After 22 days, a jugular catheter was placed and normal saline continuously infused for 10 days (days 22-32). Then TPN-100, providing 100% of rats daily energy needs, was infused for 3 days (days 32-35). During the post-SO/TLD and postjugular catheterization periods and during TPN-100, SFI was the same in SO controls and TLD group. However, TLD rats had decreased MZ and MD (interpreted as early satiety) and increased MN (interpreted as increased hunger) to maintain the same SFI as control rats. Although total SFI was not influenced by TLD, it significantly affected feeding pattern, suggesting that the neural isolation of the liver from the brain produces altered hypothalamic regulation of not only the onset of feeding, but also satiety.

Animals↗

PubMed1991

Muscarinic-receptor functioning in tracheas from normal and ovalbumin-sensitive guinea pigs.

Responses to bilateral vagal nerve stimulation, to field stimulation, and to exogenous methacholine and histamine were compared in tracheas isolated from (a) saline injected (i.p.) and saline-aerosol exposed guinea pigs (control), (b) ovalbumin-sensitized and saline-aerosol exposed (sensitized) guinea pigs, and (c) ovalbumin-sensitized and 2% ovalbumin-aerosol exposed (challenged) guinea pigs. Tracheal pressor responses (cmH2O; 1 cmH2O = 98.1 Pa) to nerve and field stimulation, and maximal responses to methacholine and histamine were significantly increased in animals from group c compared with groups a and b. Dose-response lines in response to the two agonists, expressed as percent maximal contraction, did not differ among the groups. The M1 antagonist pirenzepine (0.1-10 nM) selectively reduced responses to nerve stimulation in all three groups. The M2 antagonist gallamine potentiated responses to nerve or field stimulation in all three groups. We conclude that M1, M2, and M3 muscarinic receptor functioning is similar in control and ovalbumin-sensitized guinea pigs. Changes in post-receptor transduction mechanisms may mediate the increased responsiveness noted in animals from group c.

Aerosols↗

PubMed1991

Effects of continuous graded total parenteral nutrition on feeding indexes and metabolic concomitants in rats.

The influence of graded amounts of total parenteral nutrition (TPN) on food intake and feeding indexes was investigated in 90 rats housed in Automated Computerized Rat Eater Meter metabolic cages with free access to water and chow. When food intake was stable after catheter placement, 10 control rats continued with the 3 ml/h normal saline used for catheter patency, whereas study rats were given graded TPN continuously for 3 days, amounting to the equivalent of 26% (TPN-26), 53% (TPN-53), 81% (TPN-81), or 114% (TPN-114) of their daily caloric needs. TPN consisted of glucose, fat, and amino acids in the caloric ratio of 50:30:20. In study rats, the graded TPN depressed food intake, meal number, meal size, and eventually food consumption rate, meal sniffs, and intermeal sniffs in a dose- and time-dependent manner. During graded TPN, rats decreased total food intake by eating fewer, smaller, shorter meals at a decreasing consumption rate; sniffing activities were correspondingly curtailed. Stopping TPN led to normalization of feeding indexes. Blood glucose did not change while plasma insulin rose with graded TPN. A decrease in hepatic glycogen and an increase in hepatic triglycerides occurred. Plasma valine, phenylalanine, and methionine rose in a TPN dose-dependent manner. TPN-26 and TPN-53 significantly decreased whole brain amino acids; with TPN-114 no change occurred. Brain influx of tryptophan remained unchanged, but a progressive decrease in brain influx of tyrosine occurred. Whole brain dopamine and serotonin were depressed with TPN-26 and TPN-81 but were normal with TPN-114.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗

PubMed1991

[Synthesis and analgesic activity of analogs of 4-methoxymethyl fentanyl].

In this paper, the synthesis and analgesic activities of some derivatives of N-[1-(2-phenylethyl)-4-methoxymethyl-4-piperidinyl]-N-propionylanilin e (4-methoxymethyl fentanyl) are reported. In mouse hot plate test, most compounds in this series showed strong narcotic analgesic activities but their activities were lower than those of compounds in the series of 4-methoxycarbonyl fentanyl.

Analgesics, Opioid↗

PubMed1990

Automated computerized rat eater meter: description and application.

A real-time Automated Computerized Rat Eater Meter was developed by modifying commercially available metabolic cages. Food access via a feeding tunnel was monitored by photocells. Food consumption was measured by an electronic scale. The signals thus generated were processed by a computer. This allowed us to continuously measure the spontaneous feeding behavior of free-feeding nondeprived Fischer rats for a sum total of 35 study days. Based on our data, we defined a meal as an episode of food consumption preceded and followed by at least 5 minutes of no feeding. Fischer rats showed periodic nychthemeral eating behavior. Food consumption, number of meals, meal sniffs, intermeal sniffs, and, consequently, eating activity were greater during the dark cycle than the light cycle. Meal duration, meal size, and thus food consumption rates remained constant throughout both cycles. Our modification of commercially available metabolic cages provides unique data for continuously monitoring rat feeding patterns over prolonged periods of time.

Animals↗

PubMed1990

[Synthesis and analgesic activity of 1-substituted derivatives of 4-methoxycarbonyl-4-N-propionylanilinepiperidine].

In this paper, the synthesis and analgesic activities of a series of 1-substituted derivatives of N-[1-(2-phenylethyl)-4-methoxycarbonyl-4-piperidinyl]-N-propionylanil ine (4-methoxycarbonyl fentanyl) are reported. Preliminary pharmacological results showed that most compounds in this series exhibited typical morphine-like action and that replacement of beta-phenyl group in the 1-position of piperidine ring of 4-methoxycarbonyl fentanyl by some substituents e.g., some substituted vinyl groups, heterocyclic (or alcyclic) radicals, alkyl groups or N-methyl-anilino groups, can keep strong analgesic activity. Especially, some substituted vinyl groups were found to be effective groups which could replace 1-beta-phenyl group of 4-methoxycarbonyl fentanyl. Compounds N-[1-(3, 4-dimethyl-3-pentenyl)-4-methoxycarbonyl-4-piperidinyl]-N- propionylaniline(1321) and N-[1-(4-methyl-3-pentenyl)-4-methoxycarbonyl-4-piperidinyl]-N- propionylaniline(1302) exhibited higher analgesic activity than that of 4-methoxycarbonyl fentanyl.

Analgesics, Opioid↗

PubMedDate not supplied

Effect of tryptophan and cyproheptadine on food intake.

Whether tryptophan in the usual dose found in total parenteral nutrition (TPN) solutions caused a decrease in food intake was investigated in 16 adult male Fischer 344 rats. A jugular venous catheter was placed, and patency was maintained with a continuous infusion of normal saline at 3 ml/hr. After a 10-day recovery period, eight normal saline control rats were sacrificed and the remaining eight rats were given a parenteral nutrition solution (PN-50) at 3 ml/hr, providing 50% of the rat's daily energy requirement as 5% dextrose and 2% Intralipid. On day 14, study rats were further divided into two subgroups. Subgroup A received tryptophan (180 mg/day) added to the solution for 5 days. Subgroup B received the serotonin-receptor blocker, cyproheptadine 24 mg/kg/day, continuously for 5 days, and on day 16, tryptophan (0.25% = 180 mg/kg/day) was added to the solution for 3 days. Chow and water was continuously available and spontaneous food intake was measured daily. Study rats were sacrificed on day 19. Plasma amino acids and insulin and whole brain biogenic amines were compared with those in control rats using Student's t-test. With administration of PN-50, spontaneous food intake decreased to about 60% compared with the pre-PN level. The addition of tryptophan to the continuous infusion of PN-50 did not decrease spontaneous food intake further.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗

PubMedDate not supplied

The early cancer anorexia paradigm: changes in plasma free tryptophan and feeding indexes.

Tumor growth is accompanied by an anorexia mediated by humoral factors that appear to influence appetitive mechanisms in the brain. Because tumor resection is followed by resumption of normal food intake, the circulating anorexigenic substance(s) are produced either by the neoplastic tissue or by the host in response to the tumor. Increased levels of plasma free tryptophan and plasma ammonia have been proposed to mediate cancer anorexia. With animal models, it is often difficult to ascertain whether changes in food intake depend upon metabolic changes or the progressively increasing tumor mass per se. The feeding patterns and biochemical changes that occur during tumor growth were evaluated in 96 male Fischer rats that were inoculated with 10(6) methylcholanthrene sarcoma cells or saline (controls). Rats were placed into metabolic cages equipped with an Automated Computerized Rat Eater Meter to continuously determine meal size and meal number. Plasma free tryptophan and ammonia were evaluated 6, 10, 16, 18, 22, and 26 days after tumor inoculation. Anorexia developed by day 17-18, when food intake started to decrease via a decrease in meal size but not meal number and reached 60% of control by day 26. However, long before anorexia developed, free tryptophan was significantly higher 6 days after tumor inoculation, and the greatest increase occurred after 18 days. Ammonia did not differ from control at any time. Data confirm tumor-associated increases in plasma free tryptophan that occurred before the manifestation of anorexia and support a possible role of brain serotonin in cancer anorexia.

Ammonia↗