Effects of stress and ebiratide (Hoe-427) on free-choice ethanol consumption: comparison of Lewis and Sprague-Dawley rats.

The effects of immobilization stress, isolation stress and administration of Hoe-427 on free-choice consumption of ethanol by Lewis and Sprague-Dawley rats were studied. The animals were offered two-bottle choice consumption of 0.2% saccharin and 10% ethanol/0.2% saccharin, then exposed to 4 days of immobilization stress or isolation stress on an irregular, unpredictable schedule or 4 days of i.p. doses of Hoe-427 at 1800 hours. Both stresses resulted in significant decreases in ethanol consumption during the stress period. Hoe-427 produced a significant decrease in ethanol consumption, in a dose-dependent manner. Saccharin consumption was not significantly affected by any of the treatments. The ability to correlate the Lewis and Sprague-Dawley rat response further aids in supporting the role of the adrenocorticotropic peptide in the development of ethanol consumption.

Pharmacological studies of centrifugation-induced analgesia.

Subjecting rats to a brief period of centrifugal rotation produces a brief analgesia (1-2 min) that is similar to that produced by pretreatment with morphine. The effect of the morphine is blocked by naloxone, while that of the centrifugal rotation is only partially blocked by the same dose of naloxone. Cholinergic blocking agents such as scopolamine are also capable of partially blocking the rotational-induced analgesia. The combination of pretreatment with scopolamine plus naloxone is capable of completely blocking the rotational-induced analgesia, suggesting the involvement of both central cholinergic and endogenous opioid components.

Subcellular distribution of tissue radiocopper following intravenous administration of 67Cu-labeled Cu-PTSM.

The subcellular distribution of radiocopper in the brain and liver of rats has been determined following i.v. administration of Cu-PTSM, pyruvaldehyde bis(N4-methylthiosemicarbazonato)copper(II), labeled with copper-67. Homogenized tissue samples were separated by differential centrifugation into four subcellular fractions: (I) cell membrane + nuclei; (II) mitochondria; (III) microsomes; and (IV) cell cytosol. Upon sacrifice at 10 min post-Cu-PTSM injection, brain fractions, I, II, III and IV contain 35 +/- 12, 11 +/- 3, 2.8 +/- 1.3 and 51 +/- 7% of brain activity, respectively (n = 4). In animals sacrificed 24 h post-injection the subcellular fractions of brain tissue show little change from the radiocopper distribution seen at 10 min post-injection, although the mitochondrial fraction may contain slightly more tracer and the cytosolic fraction slightly less (I, 40 +/- 10%; II, 18 +/- 5%; III, 3.4 +/- 1.5%; and IV, 38 +/- 5%; n = 5). Subcellular fractions I, II, III and IV of liver contain 25 +/- 5, 12 +/- 3, 17 +/- 4 and 46 +/- 6% of 67Cu tracer in animals sacrificed 10 min post-Cu-PTSM injection. An identical subcellular distribution of 67Cu, was found in the liver following i.v. administration of ionic radiocopper (as Cu-citrate). The liver and brain cytosolic fractions at 10 min post-injection were further separated by Sephadex column chromatography. In liver cytosol, three different radiocopper components with molecular weights of about 140,000, 41,000-46,000 and 10,000-16,000 Da were found. In the brain supernatant fraction, most of the radiocopper was bound to a single low molecular weight cytosolic component (14,000-16,000 Da).(ABSTRACT TRUNCATED AT 250 WORDS)

Free-choice ethanol consumption by rats: effects of ACTH4-10.

The individual and interactive effects of immobilization stress, ACTH11-24 and ACTH4-10 on the free-choice consumption of ethanol in rats were studied. Stress and ethanol both result in activation of the HPA axis and release of ACTH1-39. The animals were offered a two-bottle choice consumption of 0.2% saccharin and 10% ethanol. They were exposed to immobilization stress or IP injections of ACTH4-10 or ACTH11-24 on an irregular, unpredictable schedule. Stress resulted in a decrease in ethanol consumption during the stress period while ACTH11-24 was devoid of any effect. The ACTH4-10 fragment produced an almost complete block of ethanol consumption during the injection period. Saccharin consumption was not affected by any of the above treatments. These results suggest an important role for ACTH4-10 (produced from ACTH1-39) in ethanol consummatory behavior in rats.

Antagonism of physostigmine induced hypothermia and neuroendocrine changes following exposure to different environmental temperatures.

1. The magnitude of physostigmine-induced hypothermia increased with decreasing environmental temperature. 2. The hypothermic response was accompanied by significant changes in plasma levels of corticosterone, glucose and fatty acids. 3. Central cholinergic mediation appears to be a significant component of physostigmine-induced hypothermia and neuroendocrine changes at moderate temperature. 4. At lower ambient temperatures cholinergic blockers produced less antagonism of physostigmine-induced effects. 5. The decreased effectiveness of cholinergic blockers at low environmental temperatures and the increased plasma fatty acid levels under almost all conditions studied may be of importance in considering long term therapy with cholinergic agonists.

The effect of Hoe-427 (an ACTH4-9 analog) on free-choice ethanol consumption in male and female rats.

Ethanol consummatory patterns of individual male and female rats and the effects of Hoe-427 (Ebiratide), an ACTH4-9 analog, thereon, were studied in a test system using 24 hour, two-bottle free choice consumption between 0.2% saccharin and 10% ethanol in 0.2% saccharin. Single, daily i.p. doses (0.03mg/rat) of either ACTH4-10 or its analog resulted in a significant reduction of daily ethanol consumption with no effects on saccharin consumption. After 4 days of treatment, male rats consistently exhibited a rebound increase in ethanol consumption; this effect was not seen in females. The daily ethanol consummatory patterns of the female animals seemed to exhibit a 4-6 day cyclic rhythymicity, suggesting an interaction with estrous cycles. These results support a role for ACTH4-10 in the initiation of ethanol consummatory behavior in rats and suggests the existence of sex differences in this phenomenon.

Effects of environmental temperature on hypothermia and neuroendocrine changes induced by soman.

The effects of environmental temperature on body temperature and neuroendocrine parameters were evaluated following a single acute dose (60 micrograms/kg) of soman. Plasma levels of corticosterone, glucose, and free fatty acids, as well as acetylcholinesterase activity in plasma, erythrocytes, and brain were determined over a 96-hr time course in rats maintained at 23-25, 14-16, and 3-5 degrees C. Considerable inhibition of plasma and erythrocyte acetylcholine hydrolysis activity was observed after administration of soman at all three environmental temperatures. The degree of hypothermia in all soman-treated rats in each environment tested was associated with the amount of brain acetylcholinesterase inhibition. In animals maintained at 23-25 and 14-16 degrees C, changes in plasma corticosterone levels were influenced by central acetylcholine hydrolysis. Hyperglycemia was found only in rats with greater than 45% brain inhibition regardless of environmental temperature. However, the plasma concentration of glucose over the 96 hr test period varied in relation to the hydrolysis of acetylcholine in soman-treated rats. Recovery of plasma acetylcholinesterase was more rapid at lower environmental temperatures. A greater inhibition of central acetylcholinesterase was found in soman-treated rats exposed to 3-5 degrees C. Soman may be more toxic at low environmental temperatures.

Differential effects of central and peripheral cholinergic blockade on water consumption by rats.

Atropine (5 mg/kg, s.c., twice daily) had no significant effect on 24-h water consumption on day 1 of treatment; on subsequent days the rats showed a significant increase. Procyclidine (5 mg/kg, s.c., twice daily) had a similar effect, except that the increase in daily water consumption began on the third day of treatment. Methylatropine (5 mg/kg, s.c., twice daily) markedly depressed water consumption on day 1; from the second day on no significant effects on 24-h water consumption were seen. The results suggest that the dipsogenic actions of cholinergic blocking agents on 24-h water consumption involve central rather than purely peripheral actions.

Amphetamine enantiomers and rat consummatory behavior: a new perspective.

The anorectic actions of amphetamine have been known for over forty years, yet the precise relationship(s) between the enantiomeric forms of the drug and anorexia is not clearly understood. Previous studies have utilized primarily racemic amphetamine or its d-isomer in the analysis of feeding behavior. In the present investigation, a detailed examination of the effects of single and repeated equiactive doses of d- and l-amphetamine on food consumption by adult male rats was undertaken with emphasis on aspects of tolerance development. Weight loss and pattern of daily food intake differed depending upon the isomer, dose, and degree of tolerance. Two types of tolerance were seen with both isomers, an initial tolerance with a decrease in efficacy between days 1 and 2, and a later gradual decrease in efficacy over 12 days of repeated dosage. Rats tolerant to the anorectic effects of d-amphetamine were only minimally affected when challenged with an equiactive anorectic dose of l-amphetamine, while rats tolerant to the anorectic effects of l-amphetamine showed a significantly depressed food intake and modified eating pattern when challenged with an equiactive dose of d-amphetamine. Therefore two-way cross tolerance, as previously assumed, does not completely exist between low equiactive doses of d- and l-amphetamine.

Time course of physostigmine effects on neuroendocrine responding at varying environmental temperatures.

1. Hypothermia was found to be related to both the dose of physostigmine and the environmental temperature. 2. Plasma corticosterone levels were elevated above controls regardless of dose of physostigmine or environmental temperature. 3. Plasma free fatty acid levels appeared to be inversely related to physostigmine-induced hypothermia. 4. A hyperglycemic response was observed under all experimental conditions at 0.5 hours and 1.0 hour post injection. 5. Significant inhibition of brain acetylcholinesterase was observed, whereas, plasma and erythrocyte acetylcholinesterase activity was inconsistent.

The fate and toxicity of butyl nitrites.

In summary, all four butyl nitrites were found to be moderately toxic compounds in mice, especially when given PO, TBN was the least toxic and also the least potent in producing methemoglobinemia.

The role of the hypothalamic-pituitary-adrenocortical axis in post-stress induced ethanol consumption by rats.

1. Previous studies conducted in our laboratory demonstrated that rats given a choice between a 0.1% saccharin solution or 10% ethanol/0.1% saccharin solution and repeatedly exposed on an unpredictable basis to stressful stimuli, consumed increasing quantities of the ethanol solution following cessation of stressor presentation as compared to nonstressed control rats. 2. Stressful stimuli potently activate the hypothalamic-pituitary-adrenocortical (HPA) axis, thus a systematic investigation of the HPA axis and its involvement in post-stress induced ethanol consummatory behavior was undertaken. 3. Exposure to repetitive unpredictable stressful stimuli did not induce the free-choice consumption of ethanol in either hypophysectomized rats or chronic dexamethasone treated rats. 4. Adrenalectomized rats exposed to chronic unpredictable stressful stimuli consumed increased quantities of ethanol following cessation of stressful stimuli in both a quantitative and qualitative manner which mirrored that of intact animals. 5. Repeated intravenous administration of exogenous adrenocorticotropin (ACTH1-39) on an unpredictable basis also induced ethanol consuming behavior, following the discontinuation of its administration. 6. These results suggest that elimination of the pituitary or pharmacological antagonism of stress-induced HPA activation will prevent post-stress induced ethanol consummatory behavior. 7. Conversely, activation of a functional hypothalamic-pituitary system or repeated administration of exogenous ACTH1-39 will initiate ethanol consumption in rats. 8. Thus, hormones secreted from the pituitary, namely ACTH, appear to play a crucial role in the post-stress induced initiation of ethanol consuming behavior in rats.

Effects of anorectic agents in rats bearing the Walker-256 tumor.

Since changes of levels of biogenic amines have been found in some brain areas of rats bearing the Walker-256 tumor, a study was performed to assess the actions of three anorectic agents in such animals. The results obtained by dosage of d-amphetamine, fenfluramine or mazindol, on days 5 and 8 after tumor implantation, failed to demonstrate conclusively any predominant modification of a dopaminergic, noradrenergic, or serotonergic system in the anorectic effects of these agents.

Drug interactions with ethanol. Effects on body temperature and motor impairment.

Single doses of d-amphetamine, chlorpheniramine or diazepam were combined with ethanol under two conditions: (i) in drug-naive mice and (ii) in mice which had been given a single dose of ethanol 72 hr previously. Ethanol was administered orally at doses of 6.0, 3.0 or 1.5 g/kg; doses of d-amphetamine, chlorpheniramine or diazepam were given intraperitoneally. Three parameters were measured; changes in rectal temperature, forced motor coordination, as evaluated by rotarod performance and concentrations of ethanol in blood. d-Amphetamine and chlorpheniramine attenuated the hypothermia induced by ethanol but had no effect on the motor-impairing effect of ethanol. Hypothermia induced by diazepam was unaffected by ethanol, but the combination appeared to impair maximally rotarod performance. Concentrations of ethanol in blood did not differ between ethanol-naive mice and mice which had received the same dose of ethanol 72 hr previously. Changes in body temperature and intoxication have been attributed to central actions of ethanol; however, the differential results obtained from the interactions between these drugs suggest differing sensitivities of the various systems which are affected by ethanol.

Differential analgetic actions of amphetamine enantiomers in the mouse: a drug-drug interaction study.

A series of agents were tested for their ability to interact with the analgetic actions of either d-amphetamine (d-AMP) or l-amphetamine (l-AMP), or morphine in rats using the hot plate procedure. The analgetic action of l-AMP was potentiated by morphine and slightly antagonized by naloxone; it was antagonized by clonidine, alpha-MT, yohimbine, fluoxetine and metergoline, but enhanced by PCPA. The analgetic action of morphine was antagonized by both naloxone and PCPA. The analgetic actions of l-AMP and morphine appear to involve different biogenic amine systems.

Stress-induced consumption of ethanol by rats.

Rats were maintained in a continuous choice situation for consumption of either 0.1% aqueous saccharin or 10% ethanol- 0.1% saccharin with daily tube position reversal and 24 hour fluid consumption measurement. After a stabilized baseline was achieved, groups were exposed to either no stress, or to an unpredictable schedule of isolation or immobilization stress for 14 days. During baseline and stress-exposure periods, the rats consumed predominantly the saccharin solution. Upon cessation of the stress exposures the isolation and immobilization groups markedly increased their consumption of the ethanol solution, reaching intakes as high as 9.1 g/kg/24 hours in 2-3 weeks. In addition, after 3 weeks of ethanol consumption, placement of saccharin in both tubes resulted in the stressed animals preferentially consuming from the tube that should have contained ethanol. The results suggest that unpredictable exposure to stressful stimuli can, upon cessation of exposure, induce an alcohol consummatory behavior in rats.

Subchronic toxicology of butyl nitrites in mice by inhalation.

Mice were exposed by inhalation to n-butyl, iso-butyl sec-butyl or tert-butyl nitrite in a dynamic airflow chamber 7 h per day for 60 days at concentrations that caused less than 20% fatalities. Under these conditions, body-weight gain was depressed over the first 30 days by all four compounds, but returned to normal over the final 30 days for all compounds except tert-butyl nitrite. Spleen weights were increased by all four butyl nitrites, and lung weights were increased by all except sec-butyl nitrite. Kidney weights were increased by iso-butyl and sec-butyl nitrites, but decreased by the tert-butyl compound. Liver weights were increased by iso-butyl nitrite exposure and decreased by tert-butyl nitrite exposure. The results are consistent with the hypothesis that a significant aspect of butyl nitrite toxicity is due to the resultant methemoglobinemia.

Brain catecholamine alterations accompanying development of anorexia in rats bearing the Walker 256 carcinoma.

In the present study, the relationship between central catecholamine levels and the anorexia induced by Walker 256 carcinoma was investigated. Results indicate that the anorexia is not due to depletion of central catecholamines. Tumor bearing rats sacrificed at night, when spontaneous food intake is selectively depressed, showed increased norepinephrine levels in the hypothalamus, cortex and hippocampus and increased dopamine levels in the striatum, midbrain, and cortex. Increased nighttime hypothalamic norepinephrine levels were positively correlated with the magnitude of spontaneous food intake in tumor rats.

Comparative biochemical responses of rats to different stressful stimuli.

Adult male rats were exposed to single applications of one of three stressful stimuli (low environmental temperature, immobilization, random footshock) for periods up to 4 hours and plasma levels of corticosterone (PCS), fatty acids (PFA), and glucose (PGL) were determined at various points during the stress exposure and 1 and 2 hours post-exposure. The levels of PCS were increased by all 3 stressful stimuli in a similar temporal pattern, with the greatest magnitude of effect seen for immobilization and the least for cold exposure. The time courses of increased PFA levels were similar for immobilization and cold exposure; the response to foot shock was delayed in onset by 2 hours. The PGL response was minimal for cold exposure and foot shock, but showed a marked elevation during the first 2 hours of immobilization. The results suggest that the response pattern obtained is characteristic of the stressful stimulus employed, with PCS showing the least degree of specificity.