Emil Bobyock

Induction of physical dependence in rats by ethanol inhalation without the use of pyrazole

Abstract Rats were exposed to increasing air ethanol concentrations (14 to 28 mg/liter) over a 10-day period without the use of pyrazole. There was a positive correlation between the rising air ethanol concentrations in the chamber and the concentrations of ethanol in the blood. On Day 10 the animals were removed from the chamber with a mean blood ethanol concentration of 3.13 mg/ml and observed for signs of withdrawal over a 24-hr period. During this time all animals manifested spontaneous signs of withdrawal and convulsions on handling. There was a positive correlation between the spontaneous signs and convulsions on handling. The disappearance of ethanol from the blood followed zero-order kinetics over the first 7 hr. In the withdrawal phase of the experiments a definite negative correlation existed between the decreasing blood ethanol concentrations and the rise in the scores for convulsions on handling. This inhalation procedure is a simple, reproducible approach for causing physical dependence on ethanol in rats without the use of pyrazole and with the maintenance of original body weight.

Physical dependence on ethanol: Rate of ethanol clearance from the blood and effect of ethanol on body temperature in rats

Abstract An inhalation procedure for the administration of ethanol without the use of pyrazole was employed to produce physical dependence on ethanol in rats. A reduction in body temperature was noted at the latter part of the induction phase and in the early hours of withdrawal. In the withdrawal phase the animals experienced convulsions on handling and sponataneous signs of withdrawal. To investigate the rates of ethanol clearance from the blood po and ip routes of ethanol administration were used. A significant enhancement of the rate of ethanol disappearance from the blood was measured in the animals at 48 hr following 10 days of ethanol exposure. Also at this 48-hr time period the usual hypothermic response to ethanol administration was lost in these animals as compared to a control group and to animals receiving ethanol ip, at 7 days after exposure to ethanol vapor. The data indicated that the loss of hypothermic effect from ethanol might be a factor in the increased rate of ethanol clearance. However, in studying the rate of ethanol disappearance from the blood in nondependent animals at 34°C which prevented hypothermia, there was no difference in the rates of ethanol clearance as compared to controls at 23.5°C where the hypothermic effect from ethanol was present. It appears that body temperature does not play a role in the observed acceleration of ethanol clearance from the blood in animals which have undergone withdrawal.

Vasoactive Intestinal Peptide Interacts with Alpha-adrenergic-, Cholinergic-, and Substance-P-mediated Responses in Rat Parotid and Submandibular Glands

Secretory dose-response curves were obtained with both acetylcholine and phenylephrine treatment in rat parotid and submandibular glands. Vasoactive intestinal peptide (VIP), which produced relatively low volumes of protein-rich saliva in rat salivary glands, also enhanced acetylcholine-, phenylephrine-, and substance-P-mediated fluid and protein secretion when administered in combination with these agents. The specific mechanisms involved in the synergistic actions of VIP with substances such as acetylcholine, phenylephrine, and substance P, which are primarily linked to the production of fluid secretion in rat salivary glands, have yet to be determined.

Rates of ethanol disappearance from blood and hypothermia following acute and prolonged ethanol inhalation

Abstract An inhalation procedure was employed for the acute and prolonged administration of ethanol. The rate of ethanol clearance from blood of rats following 6 hr of inhalation was significantly faster than the rates of clearance associated with the ip or po routes of administration. Also, the blood clearances from ip and po ethanol differed significantly. However, the rates of ethanol disappearance were constant for a given route, such as inhalation or ip, regardless of the dose administered. Immediately after 10 days of ethanol inhalation, the rate of ethanol elimination was not accelerated when compared to the results obtained for 6 and 24 hr of inhalation. When the animals were again treated for 6 hr with ethanol vapor 48 hr post-10-day exposure, a significant enhancement of the rate of ethanol disappearance from the blood was observed. In another experiment, utilizing a 24-hr period of ethanol exposure, it was possible 48 hr later to separatethe accelerated rate of ethanol clearance from blood and the concomitant loss of hypothermia, which previously had been observed to occur 48 hr after prolonged ethanol inhalation. In addition, the data suggested that an increased rate of ethanol clearance is not a contributory factor to the loss of hypothermia, when these two events occur concurrently. Therefore, it appears that functional tolerance rather than metabolic tolerance was observed. Finally, when various ip doses of ethanol were administered to naive rats, it was found that a minimal peak blood ethanol concentration of 1.48 mg/ml had to be attained to produce hypothermia.

Lead and δ-aminolevulinic acid concentrations in human parotid saliva

Abstract Quantitative values of lead and δ-aminolevulinic acid in normal human parotid saliva were determined and were found to be 3.1 (±0.5) and 10.2 (±0.6) μg/100 ml, respectively. The relationship of salivary lead concentration to blood lead concentration was examined. For the experimental population studied, parotid saliva was estimated to contain approximately 13% of the blood lead concentration. No significant difference was found between parotid saliva and plasma δ-aminolevulinic acid concentrations.

Effects of Substance P and Substance P Antagonists on Rat Salivary Secretion

The intra-arterial infusion of substance P produced dose-related responses of both parotid and submandibular salivary secretion in anesthetized rats. The substance P-induced secretion in both glands was inhibited by the substance P analogues [D-Arg 1, D-Trp7,9, Leu 11 ]-substance P and [D-Arg 1, D-Pro 2, D-Trp7,9, Leu 11 ]-substance P, but not by [D-Pro 2 , D-Trp7,9]-substance P. The profiles of protein and calcium levels obtained with substance P-induced salivary secretion for both glands were similar to those produced by acetylcholine stimulation and were not altered by the substance P analogues.

A study on regional brain calcium concentrations following acute and prolonged administration of ethanol in rats

Abstract Regional brain calcium concentrations were assessed after acute and chronic ethanol administration. Prolonged exposure to ethanol was accomplished by a 10-day inhalation procedure. Acute administration of ethanol in doses of 1.0, 2.0, and 3.0 g/kg failed to alter calcium content in the cerebellum, cortex, hypothalamus, midbrain, and pons-medulla 30 min after injection. However, ethanol at 4.0 g/kg reduced brain content in the hypothalamus, midbrain, and pons-medulla. When a 90-min interval between ethanol administration (2.0 g/kg) and sacrifice was used, no change was found in the calcium concentration of the five regions examined. During the induction of physical dependence on ethanol, no alteration in the brain calcium content was observed when compared with controls. In the withdrawal phase, which followed 10 days of ethanol inhalation, regional brain calcium concentrations were similar to control values. These animals were monitored up to 7 days postexposure. In experiments which involved acute administration of reserpine (5 or 10 mg/kg), it was shown that the 10 mg/kg dose decreased calcium content only in the hypothalamus by 19.6%. Based on the data derived from this investigation it appears that calcium ions may have a limited role, if any, in the central actions of ethanol when steady-state calcium ion concentrations are considered.

5-Hydroxytryptamine Modulation of Rat Parotid Salivary Gland Secretion

5-Hydroxytryptamine (5-HT) has been reported to produce significant responses in blowfly salivary glands, but little information is available concerning its action on mammalian salivary glands. When 5-HT (0.1 μmol/L to 10 μmol/L) is infused i. a. into anesthetized rats, no salivary secretion is obtained from either parotid or submandibular glands. However, when 5-HT is infused along with a threshold concentration of acetylcholine (0-1 mmol/L), potentiation of parotid secretory response is seen with 5-HT (1 μmol/L, 260% increase; 10 μmol/L, 146% increase). Substance P (0.3 μmol/L) combined with 5-HT (1 μmol/L) also resulted in a potentiation of parotid secretion (160% increase). Protein and calcium concentrations were not altered during such treatments. No potentiation of submandibular secretion was noted. Experiments in vitro with parotid cell aggregates exhibited no potentiation associated with the combined use of 5-HT and carbachol, as measured by amylase secretion and inositol trisphosphate accumulation. The experiments indicate that 5-HT substantially modulates parotid salivary secretion in vivo; however, the in vitro findings suggest that 5-HT does not act directly on surface glandular receptors. The magnitude of the in vivo potentiation could very well implicate circulating or released 5-HT as a physiological modulator of endogenous neurotransmitter action.

Regional rat brain content of adenosine 3′,5′-cyclic monophosphate and guanosine 3′,5′-cyclic monophosphate after acute and subacute treatment with ethanol

Abstract Acute administration of ethanol (1.0, 2.0, and 5.0 g/kg, ip) to naive male rats (Sprague-Dawley) caused a dose-dependent depression of cerebellar guanosine 3′,5′-cyclic monophosphate (cGMP), and a reduction in cortical cGMP at the highest dose of ethanol. The cGMP content was not altered in the anterior hypothalamus, posterior hypothalamus, or striatum. On examining adenosine 3′,5′-cyclic monophosphate (cAMP) levels, only the area of the striatum was reduced (5.0 g/kg, ethanol). In these acute experiments there was a negative correlation between blood ethanol concentrations and body temperatures. An elevated environmental temperature (31 ± 1°C) to prevent hypothermia from ethanol administration indicated that hypothermia was not a contributory factor. In the subacute experiments animals showed at the end of 24 hr of ethanol inhalation less hypothermia than naive animals with similar blood ethanol concentrations, a reduction in cGMP in the cerebellum and cortex, but no alteration in regional brain cAMP. When the animals were injected with ethanol (2.0 g/kg, ip) 48 hr after removal from the chamber (ethanol vapor, 24 hr), ethanol produced no significant reduction in body temperature (tolerance), but a decrease in cerebellar cGMP. The cAMP content of the tissues was similar to control animals. Ethanol administration (2.0 g/kg, ip) 48 hr later to animals which were previously exposed to air only in the chamber (24 hr) demonstrated a reduction in body temperature as compared with tolerant animals, a decrease in cerebellar cGMP, and no depletion of cAMP in regional sections of the brain. From this in vivo study the data seem to suggest that brain cyclic nucleotides, particularly cAMP, may have a limited role in ethanol-induced intoxication and tolerance to the hypothermic effect of ethanol.

Collection and Quantitation of Mouse Salivary Secretions

To investigate the effects of various drugs on mouse salivary glands, a method was developed for the direct quantitative collection of salivary secretions. Available methods for the collection of salivary secretions in various species are unsuitable for reproducible studies in mice (R. 0. WOLF and S. KAMEHASHI, J Dent Res 45:979, 1966; H. D. HALL and C. A. SCHNEYER, Proc Soc Exp Biol 115:100-105, 1964; D. E. DRUM, J Dent Res 42:892, 1963). Previous work performed on rat salivary preparations in this laboratory has led to the development of a collection technique that allows quantitative measurement of salivary secretions from either the parotid or submaxillary glands, in volumes as low as 0.5 p1. This technique also allows the direct application of various drugs to the salivary glands; the drugs can be administered either by constant infusion or by single injection into the systemic circulation. Consequently, drug interactions on mouse salivary glands can be studied by a quantitative approach using dose-response curves. Mice were anesthetized with sodium pentobarbital (5.0 mg/100 gm, intraperitoneally), and tracheotomies were performed. With a dissecting microscope (Bausch & Lomb), the parotid duct, and the brachial and femoral arteries were surgically exposed for cannulation (Illustration). The parotid duct was opened by puncturing the membrane of the duct with the tip of a 23 gauge needle; a polyethylene cannula (approximate dimensions: inside diameter (ID) 0.011 inches, outside diameter (OD) 0.024 inches to ID 0.003 inches, OD 0.006 inches) was inserted into the duct. The tight fit of the cannula in the duct eliminated the need for any securing procedure at the point of insertion; however, a femoral clamp was used to secure the system at a point approximately 0.25 inches from the free end of the cannula. A calibrated polyethylene collecting cannula (ID 0.030 inches, OD 0.048 inches) was placed over the free end of the parotid