Ontogeny of suckling behavior in rats prenatally exposed to alcohol

The effect of prenatal alcohol exposure on nipple attachment behavior was studied at a number of ages in rat pups whose mothers consumed liquid diets containing 35% or 0% ethanol-derived calories (EDC) or standard lab chow during pregnancy. In the first experiment, nondeprived pups were tested in groups of three (one from each of the prenatal treatment groups) for nipple attachment to an anesthetized lab chow dam. The second experiment examined the influence of the type of test dam (35% EDC, 0% EDC, or lab chow) on nipple attachment behavior. Finally, experiment three evaluated the possibility that the data from the preceeding experiments were the result of either testing the offspring in triads or alcohol-induced alterations in maternal behavior. Rat pups from all three groups reared by their biological mothers and a group of 35% EDC offspring fostered at birth to lab chow surrogate mothers were tested alone rather than in triads. The data from all three experiments clearly indicated an age-related pattern of nipple attachment behavior; the latency to attach was shortest in 6- to 12-day-old pups and increased rapidly from 13 to 21 days of age. Prenatal exposure to alcohol significantly increased the latency to attach to the nipple and the rank order of attachment at the younger ages (three to nine days of age) but not in the older animals. Also, the prenatal effect of alcohol was independent of the type of dam to which testing was conducted, the social interaction involved in testing triads, or fostering procedures. These results suggest that prenatal alcohol exposure can interfere with the development of normal suckling behavior, which might influence normal growth.

Serum triglyceride levels in newborns and mothers at parturition

From August 1980 to March 1981, paired cord venous blood and maternal antecubital venous blood were measured for triglyceride concentrations with the enzymatic method of triglyceride G-3-PDH UV end point assay, using the Hitachi Model 716 autoanalyser. The mean value of cord serum triglyceride concentrations in the cohort of 100 normal newborns was 28 ng/100 ml and the cut-off point of P95 was 48 mg/100 ml. In normotriglyceridemic newborns and hypertriglyceridemic newborns the mean values were 29 mg/100 ml and 66 mg/100 ml, respectively. However, the mean values of the corresponding triglyceride concentrations of maternal blood were not remarkably different among these 3 groups; they ranged from 190 to 193 mg/100 ml. The cord blood triglyceride level was much lower than that of maternal blood levels, with a ratio of 15% in the cohort of normal population of newborns and mothers. These findings showed that the cord serum triglyceride level was independent of the maternal serum triglyceride concentration and was of fetal origin. The relative impermeability of the placenta to this serum constituent and the lack of utilization of fat as a major source of energy in the period of normal intrauterine fetal life may, in part, account for the low serum triglyceride level in cord blood.

Adjustment of weanling and adolescent rats to a reward condition requiring slow responding

The effects of a schedule of discontinuously negatively correlated reinforcement (DNC), in which only approach responses that take 5 sec or longer are reinforced, were studied in weanling rats that began training at 18 days of age and adolescents that began training at 60 days. Yoked partially reinforced subjects (PRF) received rewards on the same trials as corresponding DNC subjects of the same age, whereas continuously reinforced subjects (CRF) were rewarded on all trials. At the end of DNC training (210 trials), the older but not the younger DNC subjects were running slower than their yoked-PRF controls. The results are consistent with development of inhibition and suppression related to the developing brain, particularly the hippocampus.

Retention under changed-reward conditions of persistence learned by infant rats

Two experiments were performed to determine whether or not persistence acquired under reinforcement conditions of infancy can be retained and transferred to adult reinforcing conditions. In Experiment I 2 groups of rats 14-15 days of age were trained in a runway under a partial (PRF) or continuous (CRF) schedule of milk-suckling reinforcement. A 3rd group was trained under continuous nonreinforcement (NRF) conditions. The PRF and CRF groups acquired the approach response about equally, and the NRF showed a very small increase in speed. In immediate extinction, the PRF group was more resistant to extinction than its CRS counterpart. For the NRF group "extinction" produced a continuation of the low-level "acquisition" performance. Experiment II showed that persistence acquired at 14-15 days with milk-suckling reinforcement can be sustained through a 2-week retention period including a phase of CRF food-pellet reward.

Learned persistence at 11-12 days but not at 10-11 days in infant rats

In 2 experiments using milk-suckling from an anesthetized dam as the reinforcer, evidence is presented that the transitional age in rat pups for learning of persistence as a result of appetitive partial reinforcement is between 11 and 12 days of age. In Experiment I, pups 12-13 days of age showed the partial reinforcement extinction effect (PREE) whereas 10-11-day olds did not. In Experiment II, pups trained at 11-12 days and tested at Day 13 did show a PREE at Day 13 but those trained at 10-11 days did not.

Recall (versus recognition) of taste and immunization against aversive taste anticipations based on illness

Two experiments show that, after taste-aversion conditioning, rats can use external retrieval cues to recall or anticipate the aversive taste solution and avoid its location without making contact with the flavor. They also show that the rat's avoidance of a conditioned aversive taste and its consumption of the aversive flavored solution can be attenuated by giving it prior runway training in which taste reward is given inconsistently on a partial reinforcement schedule.

Bile acid pool size in relation to functional status of gallbladder and biliary lipid composition in Chinese

Bile acid pool size was measured in 10 Chinese without gallstones, 14 with pigment stones, and 10 with mixed stones by an isotope dilutin technique. Functional status of gallbladder was evaluated by intravenous cholecystogram and its gross appearance at surgery. Biliary lipid composition was also determined. The control subjects had a bile acid pool size comparable to that of Caucasians. Regardless of the nature of gallstones, bile acid pools of stone patients with functioning gallbladder were within normal range, whereas the pools of those with non- or poorly-functioning gallbladder diminished to about two-thirds of the control. Thus, the diminution of bile acid pool size was apparently the consquence of loss of storage function of gallbladder rather than the cause of production of lithogenic bile. The common bile duct bile obtained from stone patients with nonfunctioning gallbladder had a relatively high lithogenic index, at least partly related to its low total lipid concentration.

Concentration-dependence of nonelectrolyte permeability of toad bladder

A theoretical formulation was derived for the dependence of bulk solute permeability, P, defined as net flux divided by concentration gradient, delta c, across any membrane in which solute concentration is controlling for net flux, delta J. According to this formulation, delta J is stimulated by increments in trans concentration, c2, in the range c2/c1 equals 0.0--0.1. Net flux of urea across toad bladder down concentration gradients was shown to be stimulated threefold by small increments in trans urea concentration. The theory also predicts that, in the absence of concentration gradients, tracer permeability, P, defined as tracer flux divided by tracer concentration, will be independent of c provided that P equals P, but will diminish with increasing c if P/P less than 1.P/P was not significantly different from unity for urea, and both P and P were independent of c in the absence of concentration gradients. However, P/P was significantly less than unity (0.90 and 0.85) for thiourea and mannitol, respectively. In conformity with theory, P (and also P) of these two solutes, measured as c was increased by 3--4 orders of magnitude, diminished progressively. These effects are more consistent with this formulation than with transport via a saturable carrier.

Effects of electrochemical gradients on active sodium transport in toad urinary bladder

To determine the concentration dependence of active sodium transport in toad urinary bladder, bidirectional fluxes of sodium were measured at three mucosal sodium concentrations (Cm) (114, 27, and 3 mM), before and after addition of sufficient ouabain to eliminate active transport. The results permit estimation of E, the electromotive force of the sodium pump, and its conductance, ga. E averaged 137 mV and was unaffected by depolarization or by reduction of Cm; ga fell by only 40%, suggesting that a Cm of 3 mM was still above the half-maximal value for the sodium pump. However, net open-circuit transport was estimated to become zero at Cm = 6 mM, owing to backflux through the shunt path, which did not vary with Cm. The flux ratio in the active path exhibited the type of abnormality first described as "single-file pore diffusion," which is attributed to relatively tight coupling between transport and metabolism.