Paul J. Kulkosky

Behavioral effects of bombesin administration in rats

Bombesin (BBS, 0.1-4.0 micrograms) administered to the lateral cerebral ventricle (IVT) of rats decreased food intake and feeding behavior. Grooming behavior increased and resting behavior decreased as doses greater than or equal to 0.01 microgram. IVT BBS (4.0 micrograms) caused greater suppression of food-deprivation-induced food intake and feeding behavior than the same dose and volume administered intraperitoneally (IP). After IVT BBS, rats displayed more grooming and less resting than normal, but after IP BBS, rats displayed a normal frequency of grooming and more resting. IVT BBS (greater than or equal to 0.01 microgram) also decreased drinking behavior, and drinking-associated feeding, and suppressed (greater than or equal to 0.1 microgram) water-deprivation-induced water intake. When neither food nor water was present, non-deprived rats displayed increased grooming and decreased resting after IVT BBS (1.0 microgram). The results show that IVT BBS inhibits feeding markedly, but the inhibition of feeding by IVT BBS does not resemble normal satiety or the effect of IP BBS because the central inhibition of feeding is always accompanied by excessive grooming and little resting. Furthermore, since IVT BBS decreases drinking at a dose lower than that required to reduce food intake, and IP BBS does not, the specific satiety effect of IP BBS on feeding cannot be mediated solely by increasing bombesin in the cerebrospinal fluid.

Feeding and selection of saccharin after injections of bombesin, LiCl, and NaCl.

Rats injected with bombesin of LiCl showed similar suppression of food-deprivation-induced liquid diet intake, but only rats receiving LiCl avoided water-deprivation-induced consumption of a novel saccharin solution paired with injection. The data demonstrate that bombesin reduces feeding but does not induce conditioned aversion, and suggest that bombesin does not act to suppress food intake by production of gastrointestinal malaise.

Ethanol consumption of rats in individual, group, and colonial housing conditions

Rats were housed in individual cages, in a group cage, or in a naturalistic colonial habitat, and given access to food, water, 10% ethanol, and 10% ethanol in a sweetened saline solution. Rats housed in the colony ingested significantly less total ethanol than either group or individually caged rats. When the flavored ethanol solution was removed, total ethanol intakes of all groups decreased and did not differ significantly. The data indicate that the stimuli of the colonial situation act to decrease ethanol intake when a palatable ethanol solution is available.

Total avoidance of saccharin consumption by rats after repeatedly paired injections of ethanol or LiCl

Rats injected with ethanol or LiCl following consumption of novel saccharin solution drank less saccharin than non-poisoned controls on a subsequent exposure with degree of aversion positively related to dose of ethanol (2--5 g/kg). While a single pairing of saccharin with ethanol or LiCl resulted in partial avoidance of saccharin solution, repeated conditioning trials led to total avoidance of saccharin consumption by animals injected with the higher doses of ethanol or with LiCl. These results, characteristic of emetic-induced aversions, support the explanation of the limited consumption of ethanol by rats under ad lib, free-choice conditions as a result of acquired aversion to the oronasal sensory stimuli of ethanol after association with pharmacologically aversive aftereffects of consumed ethanol.

Effect of addition of ethanol and NaCl on saccharin + glucose polydipsia

Rats received an ad lib choice of food, water, and a solution containing saccharin, glucose, and NaCl solutes either as single stimuli or in combinations. Ethanol was gradually added to these vehicles or water from 0.5--15% w/v. Ethanol intakes of all groups with vehicles containing glucose were higher than intakes of the water vehicle group. Ethanol intakes of the 0.125% saccharin + 3.0% glucose + 1.0% NaCl + ethanol group were highest, peaking at greater than 9.0 g/kg/day, and this group displayed the highest blood ethanol levels. However, there was no evidence of withdrawal syndrome, nor of increased intake of unflavored ethanol by groups previously receiving flavored ethanol. It is suggested that ethanol eliminative capacity limits free-choice ethanol intake when maximized by the addition of sapid congeners.

Reduction of drinking-associated feeding by C-terminal octapeptide of cholecystokinin-pancreozymin.

Water- but not food-deprived Wistar rats receiving 30-min access to water daily were presented with a novel almond extract solution 15 min following intraperitoneal injection of either 40 Units/kilogram of C-terminal octapeptide of cholecystokinin-pancreozymin, vehicle, or 1.8 mEq/kg of LiCl. Drinking-associated feeding, but not fluid intake, was significantly reduced in the LiCl-octapeptide-injected group, and both fluid and food intakes were depressed in the LiCl-injected group. There was evidence of a conditioned taste aversion to the novel solution in a subsequent two-bottle test only in the LiCl-injected group. The results extend the generality of the feeding suppression effect of cholecystokinin-pancreozymin injection to a form of food intake by the rat other than deprivation-induced feeding. The absence of a detectable conditioned taste aversion to a novel flavor paired with octapeptide injection is attributed to a relatively low aversiveness of cholecystokinin-pancreozymin injection compared to other aversive agents such as LiCl.

Free-selection ethanol intake of the golden hamster (Mesocricetus auratus)

Female golden hamsters preferred a 10% w/v ethanol solution presented in a saccharin + glucose vehicle to water in free-selection tests. Although blood ethanol levels attained were higher than previously reported for rats in free-selection experiments, no symptoms of physical dependence on ethanol were apparent in a runway activity test for withdrawal.

The interaction of conditioned taste aversions and schedule-induced polydipsia: Effects of repeated conditioning trials

In Experiment 1, rats poisoned following schedule-induced saccharin consumption showed a moderate reduction in the schedule-induced consumption of saccharin. With repeated poisoning, schedule-induced saccharin polydipsia was markedly reduced. Acquisition of conditioned aversion under the schedule-induced procedure was significantly slower than acquisition under water deprivation. In addition, recovery of consumption of the previously poisoned solution during extinction was more rapid under schedule-induced polydipsia. Experiment 2 revealed that schedule-induced polydipsia was less sensitive to suppression by conditioned aversions than a prandial drinking condition in which subjects were equally food deprived but were given a mass feeding instead of spaced pellet deliveries, suggesting that the relative insensitivity of schedule-induced polydipsia to conditioned taste aversions is not simply a function of different levels of food deprivation. This relative insensitivity is offered as a partial basis for the occurrence and maintenance of schedule-induced alcohol polydipsia.

Blood ethanol and free-choice ethanol intake in rats and their progency

Outbred male and female Wistar rats demonstrated large and consistent interindividual variations in nocturnal blood ethanol level (BEL) during ad lib access to food, water and an ethanol solution. Mean individual BEL ranged from 0--109 mg/dl, grand mean = 25.1 mg/dl (5.5 mM). BELs of all rats correlated with free-choice ethanol intakes, but females showed significantly greater ethanol intake (female and male means = 10.5 and 8.2 g/kg/24 hr) that was unaccompanied by significantly greater BEL (female and male means = 30.6 and 19.6 mg/dl). Across three linearly derived generations, progeny of rats matched for high BELs (mean = 25.1 mg/dl), but there was no significant difference across generations in ethanol intake (respective means = 8.4 and 8.1 g/kg/24 hr). In the third derived generation, there were significant differences between high and low BEL progeny in both BEL (respective means = 35 and 15 mg/dl) and ethanol intake (respective means = 8.2 and 6.3 g/kg/24 hr).

Ethanol selection in wild-trapped agouti and laboratory albino Norway rats (Rattus norvegicus)☆

Abstract Wild-caught agouti Norway rats and Wistar albino Norway rats were habituated to the laboratory setting for 2 months and then given an ad lib 2-bottle choice of water and ethanol solution at concentrations of 1–17%, increasing 1% on consecutive days. Wistar rats displayed their typical preference for low concentrations and strong avoidance of high concentrations of ethanol, but the wild rats showed only a weak aversion for the highest ethanol concentrations. The results are discussed with reference to the higher metabolism, larger adrenal glands, and relative inflexibility of wild rats observed in previous comparisons with laboratory rats.