Brain concentrations of phenobarbital and behavioral activation or depression

Brain concentrations of phenobarbital and its effects on locomotor activity and lever responding for food reinforcement were determined at several intervals following injections into C57BL/6J mice. Phenobarbital either elevated or depressed both types of behavior depending on dose and time after injection. Excitation was noted at times and doses when brain concentration was 9 micrograms-11.5 micrograms/g tissue. Depression was initially noted at approximately 20 micrograms/g tissue. Lever responding was altered when brain concentrations of the drug were lower than those associated with corresponding effects on locomotor activity. Excitatory and depressive effects were most extensive when basal response rates were moderate or high respectively. Hence, whether phenobarbital is excitatory or depressive depends on a complex interaction of brain concentration, rate of ongoing behavior and the stimulus conditions maintaining the behavior.

Decreased ethanol consumption as a function of pregnancy and lactation in C57BL mice

The effects of pregnancy and lactation on alcohol consumption were examined in the C57BL mouse. Pregnant mice were given a two-bottle choice between water and 10% w/v alcohol solution from Day 5 of pregnancy, through two weeks of lactation, and an additional four weeks following the removal of nursing pups. Alcohol consumption was expressed in terms of g absolute ethanol per kg body weight and as an alcohol preference ratio (ml alcohol/ml total fluid). Alcohol consumption (g ethanol per kg body weight) fell below control values during pregnancy and lactation but increased to control levels during postlactation. Similarly, alcohol preference ratio was found to decline during pregnancy, and to further decrease during lactation, a trend that was reversed during postlactation. The results support the findings of decreased alcohol consumption during pregnancy in alcoholic as well as nonalcoholic women.

Ethanol, calcium, and naloxone in mice

Alcohol has been reported to produce a significant reduction in the brain calcium content of rats, which could be blocked by administration of naloxone. Ethanol pretreatment failed to decrease brain cortex calcium and, in fact, increased the calcium content at higher doses. The effects of naloxone were also studied.

Renal anomalies in mice prenatally exposed to ethanol

The current observations confirm and extend earlier data demonstrating the deleterious effects of ethanol in the C57BL/6J mouse. Ethanol given to pregnant mice from gestation-day 5 to gestation-day 11 reduced the number of mice going to full term, decreased the number of pups per litter, and lowered the birthweight of the live pups. Prenatal exposure to ethanol also produced a high incidence of hydronephrosis in the offspring.

Effect of taurine on some pharmacological properties of ethanol

Taurine was effective in reducing the hypnotic effect of ethanol but did not antagonize the effect of ethanol on seizure susceptibility, body temperature, or brain 5-HIAA concentration.

Serotonergic stimulation of pituitary-adrenal activity in the mouse

Female CF1 mice were given L-5-hydroxytryptophan (5-HTP), quipazine, or 6-methoxy-1,2,3,4-beta-carboline (6-MeO-THBC) in conjunction with various serotonergic drugs to determine if the pituitary-adrenal stimulation produced by the former compounds is serotonergically mediated. Corticosterone (CS) responses to 5-HTP were uninfluenced by pretreatment with a tryptophan hydroxylase inhibitor, p-chlorophenylalanine (PCPA), but were significantly potentiated by a serotonin (5-HT) reuptake inhibitor (Lilly 110140), attenuated by two 5-HT receptor blockers, cyproheptadine and methergoline, and almost completely abolished by 2 extracerebral aromatic L-amino acid decarboxylase inhibitors, MK 486 and a low dose of Ro 4-4602. It was also established that L-tryptophan could stimulate pituitary-adrenal activity in animals pretreated with the monoamine oxidase (MAO) inhibitor pargyline. Serotonergic drugs were generally not as effective in modulating the responses to quipazine and 6-MeO-THBC. It is concluded that (1) 5-HTP stimulates pituitary-adrenal activity in mice by being converted to 5-HT and acting on 1 or more groups of serotonergic receptors; (2) these receptors are located either in an area of the brain outside of the blood-brain barrier such as the median eminence or in a peripheral tissue(s); (3) tryptophan-derived 5-HT can stimulate these receptors, but only if allowed to accumulate by inhibiting its catabolism; and (4) it is not yet clear whether pituitary-adrenal responses to quipazine and 6-MeO-THBC are mediated by a serotonergic mechanism.

The effects of methaqualone on pituitary-adrenocortical activity in mice

Methaqualone produces a dose- and time-dependent increase in plasma corticosterone concentration in mice. Acute studies showed that this effect is largely independent of methaqualone-induced hypothermia but can be blocked by pretreatment with dexamethasone, thus demonstrating that the adrenal cortex is not being directly stimulated. It is not clear whether the pituitary-adrenal activation is primarily caused by methaqualone itself or by a hepatic metabolite(s) since pretreatment with SKF 525-A failed either to potentiate or block the effect. Studies employing chronic methaqualone administration provided evidence for a rapid development of tolerance to the pituitary-adrenal effect of the drug. Dose- and time-response studies demonstrated a parallel between plasma concentrations of methaqualone and the stimulation of pituitary-adrenal activity. Furthermore, drug concentrations 1 h following methaqualone administration were diminished in chronically pretreated animals was compared to those previously untreated, suggesting that an altered metabolism of methaqualone may be responsible for the development of tolerance.

The effects of methaqualone on the seizure susceptibility of mice

Methaqualone produces dose- and time-dependent decreases in susceptibility to electrically, chemically, and sound-induced seizures. The antagonism of methaqualone to electroconvulsive shock can be dissociated from its effects on temperature regulation and plasma corticosterone. Studies with SKF525A, a drug known to block enzymes in the liver that metabolize drugs, suggest that methaqualone, rather than a metabolite produced in the liver, is responsible for its anticonvulsant effects. Tolerance to the anticonvulsant effects of methaqualone is also demonstrated.

The effects of methaqualone on the temperature regulation of mice

Methaqualone produces dose and time dependent changes in the rectal temperature of mice. More specifically, the drug produces poikilothermia. This effect appears to be produced by methaqualone itself rather than a liver metabolite since SKF525A, a compound known to block drug metabolizing enzymes in the liver, does not abolish the phenomenon. Tolerance to the temperature altering effects of methaqualone is also shown.

Effects of serotonergic drugs on methaqualone-induced hypothermia

Methaqualone (75 mg/kg) produced a significant decrease in the rectal temperature of mice. This effect was antagonized by parachlorophenylalanine and potentiated by Lilly 110140. These compounds also decreased and increased respectively the circulating concentration of methaqualone.

Effects of single and multiple dose LSD on endogenous levels of brain tyrosine and catecholamines

The effects on brain catecholamines of seven daily doses of d-LSD 520 mug/kg injected i.p. to Sprague-Dawley rats on a tolerance dosage schedule (L X 7) were compared with the effects of a single dose of LSD (L X 1) 520 mug/kg or 1040 mug/kg, over a 90 min time course. Compared to saline controls, after a single dose of 520 mug/kg LSD, there was a significant decrease in brain norepinephrine at 30 to 60 min, a rise in dopamine at 60 min, and a small rise in brain tyrosine at early time points followed by significant decline from control levels after 60 min. The effects of a single dose of 1040 mug/kg LSD were similar to the 520 mug/kg dose but were greater in both magnitude and duration of the brain catecholamine changes. After a tolerance dosage schedule there were significant changes in the response of brain catecholamines to 520 mug/kg LSD. The rise in brain dopamine at 60 min was abolished, brain tyrosine was uniformly below both saline and L times 1 animals, and brain norepinephrine returned to control levels slightly faster.

Para-chlorophenylalanine, serotonin and killing behavior

Both p-chlorophenylalanine (PCPA) and PCPA methyl ester were found to reliably induce mouse-killing in non-killer rats only when unusually large doses were used (three successive daily injections of 300 mg/kg) and brain serotonin (5-HT) concentration was drastically reduced (about 90 percent). Neither three doses of 100 mg/kg of PCPA nor p-chloroamphetamine (3 times 3.5 mg/kg) caused similar effects in spite of the fact that these compounds depleted brain 5-HT by 85 percent and 60 percent, respectively. PCPA-induced mouse killing was reversed by 5-HTP (100 mg/kg) only when this serotonin precursor completely restored levels of 5-HT. The topography of PCPA-induced killing did not resemble normal interspecies aggression and was also directed toward fat pups. These findings suggest that 5-HT depletion might facilitate nonspecific killing reactions, but is not a sufficient condition to induce the species-specific predatory behavior in rats.