Effect of vitamin D administration during pregnancy on neonatal growth in the rat

Groups of rats on commercial diet were injected 3,000 IU (group 2) and 7,500 IU (group 3) of vitamin D3 on the 10th day of pregnancy. Compared to control pups (group 1), the pups in group 2 and 3 weighed significantly more on the 10th, 20th and 28th day of age. At 28th day of age, study of the gastrocnemius muscle revealed significantly greater organ weight, protein, DNA and RNA contents, protein/DNA and RNA/DNA ratios in group 2 and 3 pups than in controls. In the liver, whereas all these indices were significantly increased in group 3 pups, only protein/DNA and RNA/DNA ratios were significantly increased in group 2 pups. Brain weight, its RNA content and RNA/DNA ratio were significantly greater in group 2 and 3 pups than in controls. The results suggest that vitamin D administration in pregnancy promotes soft tissue growth in the pups by enhancing cellular proliferation and hypertrophy.

Sensitivity of pentylenetetrazol discrimination increased by a stimulus fading technique

The interoceptive stimulus produced by pentylenetetrazol (PTZ) is pharmacologically similar to anxiety and is used in a behavioral assay for anxiety-related stimuli (the PTZ model of anxiety). The stimulus fading technique was tested as a method to increase the sensitivity of this assay. Rats were trained with food-reward to press one lever after injection of PTZ and an alternate lever after saline. Rats initially learned the discrimination at a PTZ dose of 20 mg/kg. They were then trained with sequentially lower doses until they reliably discriminated a PTZ dose of 10 mg/kg. Substitution tests with other doses and drugs showed that, after the fading procedure, dose-response curves were shifted to lower doses for PTZ, Ro 5-3663, and nicotine Similarly, the dose of diazepam required to block the low dose of PTZ was lower than that required to block the higher dose of PTZ. These results indicated that the sensitivity of the discrimination was enhanced in rats trained to discriminate a lower dose of PTZ. Doses of nikethamide, cocaine, and yohimbine that did not substitute for the higher dose of PTZ also did not substitute for the lower dose. These data suggest that rats can be trained to discriminate a low dose of PTZ by the stimulus fading technique. Moreover, they suggest that this training method does not compromise the specificity of the discrimination.

Characterization of a pentylenetetrazol-like interoceptive stimulus produced by ethanol withdrawal

Rats were trained with food reinforcement to discriminate the anxiogenic drug pentylenetetrazol (PTZ, 20 mg/kg) from saline in a two-lever-choice task. In Experiment 1, ethanol, 8.25% w/v was given by gavage (7/day) for 4 days, with doses titrated to maintain moderate intoxication. After termination of ethanol, the rats exhibited mild overt signs of withdrawal and, in discrimination tests with saline as the test substance, they selected the PTZ lever, an effect reversed by ethanol, 2 g/kg, and by diazepam, 5 mg/kg. In Experiment 2, rats drank a nutritionally complete liquid diet containing ethanol, 4.5% w/v, for 1 week. They became tolerant to the intoxicating effect of ethanol, and blood ethanol concentration mounted with continued dosing. On termination of chronic ethanol, rats selected the PTZ lever before the onset of overt physical signs of withdrawal, and both measures returned to base line within 3 days. In Experiment 3 the percentage of rats selecting the PTZ lever after termination of ethanol depended upon the dose (up to 12.5 g/kg) and duration (up to a ceiling effect by 3 days) of ethanol administered chronically. These results indicate that a PTZ-like stimulus produced interoceptively can be demonstrated in the rat as an objective measure of ethanol withdrawal. This paradigm may provide insight into the symptom of anxiety associated with ethanol withdrawal.

CGS 8216, a benzodiazepine receptor antagonist, enhances learning and memory in mice

Mice pretreated with the benzodiazepine antagonist, CGS 8216 (2.5, 10, or 40 mg/kg, i.p.) learned a T-maze discrimination to a fixed performance criterion more rapidly than vehicle-treated mice. In retention tests conducted one week later, the drug-treated groups had better first-trial recall and greater difficulty reversing the previously trained maze habit when compared with controls, suggesting improved memory for the previously trained maze habit. The enhanced acquisition and retention following CGS 8216 was similar to that observed previously with another benzodiazepine antagonist, flumazenil (Ro 15-1788). It is postulated that CGS 8216 and flumazenil could act at benzodiazepine receptors to antagonize a tonic inhibitory influence of endogenous, diazepam-like, benzodiazepine receptor ligands on memory processes.

Autoimmunity and age-associated cognitive decline

It is suggested that the immune system may play a role in the etiology of age-associated cognitive decline and/or Alzheimer's disease. The relationship between brain-reactive antibodies (BRA) and age-associated cognitive dysfunction is reviewed and discussed. A parallel relationship between BRA increases with age and decline of avoidance learning capacity is described in mouse models. Transfer of immunity from old to young mice was found to accelerate both age-related formation of brain-reactive antibodies and age-related decline of avoidance learning capacity. Short-lived mouse genotypes with accelerated autoimmunity were found to show accelerated age-related declines in their ability to acquire an avoidance response when compared with nonautoimmune mice. Overall, these findings suggest that the immune system could be an important target for development of intervention strategies aimed at extending the intellectually competent period of life. Mice in which autoimmunity is accelerated may be useful as models for the development of such interventions.

Enhancement of learning and memory in mice by a benzodiazepine antagonist

Benzodiazepines, a class of drugs widely employed as anxiolytics and anticonvulsants, can induce impairments of learning and memory. The purpose of the present investigation was to determine if a benzodiazepine receptor antagonist, flumazenil (Ro 15-1788), could enhance learning and memory. Pretraining injection of flumazenil (2.5 to 40.0 mg/kg) was found to enhance both learning and memory in a test requiring young mice to discriminate the correct arm of a T-maze to escape mild electric shock. In a second test, which required mice to passively avoid a dark chamber after shock, flumazenil pretreatment prevented the occurrence of amnesia induced by the cholinergic receptor antagonist scopolamine. It is hypothesized that flumazenil may facilitate learning or memory processes by reversing a negative modulatory influence of endogenous diazepam-like ligands for benzodiazepine receptors.

Serum immunoglobulin E levels in patients with head and neck cancer

Serum immunoglobulin E levels were estimated in 50 patients with head and neck cancer and in 25 controls. Mean serum IgE value was significantly higher in patients with various sites of cancer in the head and neck region other than carcinoma of the tonsil. The levels increased with advancement in the stage of cancer. There was, however, no difference in mean serum IgE value with respect to the character of the lesion, to the histopathological type of growth or to radiotherapy. In patients with carcinoma of the tonsil, the mean serum IgE concentration was significantly lowered.

Effect of acute environmental heat stress on urinary water and electrolyte excretion in the rat

Plasma cortisol and urinary excretion of water, sodium, potassium, calcium and magnesium have been studied in the rat after application of heat stress. There was a significant increase in plasma cortisol level after exposure to heat. During heat stress complete cessation of urine formation was observed. In the next 30 min there was statistically significant increase in the urinary excretion of water, sodium and calcium but not of potassium and magnesium. Urinary calcium/magnesium ratio was also significantly elevated. The increase in urinary water and electrolyte excretion seemed to be mediated through prostaglandins since it could be abolished by administration of indomethacin prior to the application of heat stress. On the basis of these results, the possible role of heat stress in the genesis of urolithiasis has been discussed.

Withdrawal from diazepam substitutes for the discriminative stimulus properties of pentylenetetrazol

Rats were trained to discriminate pentylenetetrazol (PTZ, an anxiogenic drug), 20.0 mg/kg, from saline using a food-maintained two-lever-choice task. When treated chronically with diazepam (DZP) and tested with the benzodiazepine-receptor antagonist Ro 15-1788, withdrawal from DZP produced a PTZ-like stimulus in these subjects that was related directly to the dose of DZP given every 8 hr for 6 days. In contrast, only the highest dose of DZP (80 mg/kg/8 hr) given chronically produced even minimal physical signs of precipitated abstinence after Ro 15-1788. In a separate experiment, Ro 15-1788 produced a PTZ-like stimulus when given at 2-day intervals during chronic administration of DZP. In this experiment, rats were maintained on DZP, 40.0 mg/kg/6 hr for 14 days. These subjects were tested with Ro 15-1788, 40.0 mg/kg, every 2 days during days 6 through 14 of chronic DZP, and Ro 15-1788 substituted for PTZ on 4 of these 5 tests. Because these experiments involved periods of nontraining on the discrimination task, a final experiment was performed to test the stability of stimulus control in rats trained to detect PTZ. DZP was administered for up to 20 days, withdrawal was precipitated by Ro 15-1788 and after an additional 16 to 40 days of nontraining, stimulus control was tested. There was no significant decline in stimulus control over this period. These results suggest that PTZ discrimination provides a sensitive, stable assay for the detection of withdrawal from benzodiazepine dependence.

Age differences in acquisition and retention of one-way avoidance learning in C57BL/6NNia and autoimmune mice

Acquisition and 48-h retention of a step-up active avoidance response were studied in separate age groups of C57BL/6NNia mice (aged 1.5, 3.5, 6, 12, or 26 months) and five strains of genetically autoimmune mice differing in life span. The C57BL/6NNia mice showed no change in ability to acquire the avoidance response between 1.5 and 3.5 months, but showed a steady decline in that ability thereafter. Mouse strains with early-onset autoimmune disorder (NZB/B1NJ, MRL/MpJ-lpr, and BXSB/MpJ) showed declines in acquisition capability between 1.5 and 3.5 months of age, whereas mouse strains with mild, late-onset autoimmune disorder (MRL/MpJ- + and NZBWF1/J) showed stable or improved acquisition during that period. Both the C57BL/6NNia and NZB/B1NJ mice showed age-dependent declines in 48-h retention performance by 12 months of age. These findings suggested that while 48-h retention performance deficits were most related to chronological age, avoidance acquisition deficits were related to development of autoimmunity.

Adenosine deaminase activity in leprosy (a preliminary study)

Adenosine deaminase (ADA) activity was studied in 25 patients having different types of leprosy and 25 healthy volunteer as control. There was definite rise of ADA activity in BL (72.9 +/- 6.85), LL (56.7 +/- 3.35) and BT (39.1 +/- 8.28) which was statistically significant when compared to ADA activity in healthy control (9.7 +/- 0.53).

Quantal detection and homogeneous sensitivity in a pentylenetetrazol discrimination

Rats were trained to discriminate pentylenetetrazol (PTZ, 20 mg/kg) from saline in a two-lever operant task. Correct lever presses were reinforced with food under the control of a fixed ratio 10 schedule. In tests of the effect of PTZ dose on lever selection, rats selected the PTZ lever in a dose-dependent manner, with peak latency at the approximate ED50 dose (10 mg/kg). Rats usually pressed only the selected lever, regardless of dose, indicating that lever selection was a quantal (or bimodal) function of stimulus intensity. Lever biases observed during training sessions did not predict the performance of individual rats in tests with the ED50 dose. In three independent trials with this intermediate dosage, the rats selecting the PTZ lever varied from trial to trial, suggesting that rats detecting this dose did not form a stable subgroup. The pattern of lever selections across these three trials was not significantly different from that predicted by a model in which all subjects shared the same probability for detecting the drug stimulus. These results demonstrate that lever selection in a two-lever drug-discrimination task can be quantal in nature, and suggest that rats trained with PTZ, 20 mg/kg, are homogeneous in sensitivity to this stimulus.

Effect of dietary restriction with and without leucine supplementation on hepatic protein status in rats

In the present study effect of dietary restriction with and without leucine supplementation was observed on body and liver weights, and liver protein status, in adult rats. Animals were fed on two diets ad lib or were on 50 per cent and 25 per cent intakes. Dietary restriction resulted in loss of body and liver weights, hepatic protein, free-alpha-amino nitrogen and RNA contents and liver cell size (liver weight/DNA ratio). When compared with the control group, the decrease in these parameters was more in the dietary restricted leucine supplemented group. However, hepatic DNA content was not changed with the change in dietary regimen. The results suggest that leucine supplementation with dietary restriction may be more harmful for the animal than dietary restriction alone.

Enhancement of a diazepam withdrawal symptom by bicuculline and yohimbine

The role of the GABA system in producing a pentylenetetrazol-like interoceptive discriminative stimulus during withdrawal from diazepam was investigated in rats by determining the sensitivity of this system to GABAergic drugs before and after chronic treatment with diazepam. Food-restricted rats were trained to obtain a reward of food by responding on one lever following an injection of pentylenetetrazol (PTZ; 20 mg/kg) and the other lever following an injection of saline (1 ml/kg). After rats had acquired this discrimination, the effectiveness of Ro 15-1788, bicuculline and yohimbine to substitute for pentylenetetrazol was determined. Prior to chronic treatment with diazepam, rats selected the appropriate lever for saline after Ro 15-1788 and the appropriate lever for pentylenetetrazol after bicuculline (0.04-2.5 mg/kg) or yohimbine (0.16-5.0 mg/kg). Although the selection of the appropriate lever for pentylenetetrazol was dose-dependent, full substitution for pentylenetetrazol was not obtained with either drug as larger doses of bicuculline produced convulsions while the rats began to select the appropriate lever for saline after larger doses of yohimbine (bell-shaped curve). Diazepam blocked the pentylenetetrazol-like interoceptive discriminative stimulus for bicuculline. The rats were then injected with diazepam (80 mg/kg/8 hr) for 24 days. Upon termination of the administration of diazepam, the animals were tested for lever-selection following the administration of saline, Ro 15-1788 (10 mg/kg), bicuculline (0.32, 0.64 and 1.25 mg/kg) or yohimbine (0.16, 0.64 and 2.5 mg/kg). After saline, 33% of the rats selected the appropriate lever for pentylenetetrazol whereas selection of this lever was enhanced after Ro 15-1788, bicuculline or yohimbine.(ABSTRACT TRUNCATED AT 250 WORDS)

Modulation of the discriminative stimulus produced by pentylenetetrazol by centrally administered drugs

Pentylenetetrazol is anxiogenic in humans and produces an interoceptive discriminative stimulus in rats which is mimicked by anxiogenic drugs and other treatments and antagonized by anxiolytic drugs. It was proposed that the discriminative stimulus of pentylenetetrazol originates centrally. This hypothesis was tested by injecting small amounts of anxiogenic or anxiolytic drugs into the brain and comparing their ability to mimic or block, respectively, the response to pentylenetetrazol, observed after systemic injection. Food-restricted rats were trained in a two-lever operant task to discriminate the interoceptive discriminative stimulus produced by pentylenetetrazol. Intraperitoneal or intracerebroventricular injection of Ro 5-3663 was substituted in a dose-dependent manner for the stimulus produced by systemically administered pentylenetetrazol. Diazepam injected systemically, blocked the pentylenetetrazol-like stimulus associated with Ro 5-3663 administered systemically or centrally. Midazolam injected intracerebroventricularly and in a dose-dependent manner, antagonized the discriminative stimulus produced by systemic injection of pentylenetetrazol. When injected into the amygdala, midazolam also antagonized in a dose-dependent manner the pentylenetetrazol-induced stimulus. Thus, these data suggest that there are sites in the CNS for both the initiation of a pentylenetetrazol-like stimulus by Ro 5-3663 and the antagonism of the stimulus produced by pentylenetetrazol by midazolam.

Serum enzymes in head and neck cancer III

Serum adenosine deaminase (ADA) levels were estimated in a group of 40 patients with head and neck cancer. The mean value was significantly higher in patients compared to controls. The increase was higher in cases of ulcerative growths than of proliferative growths, and activity was increased with advancement in the stage of the cancer. After radiotherapy, a gradual and significant decrease in serum ADA activity was observed.

Evaluation of enzymes in serum and cerebrospinal fluid in cases of cerebrovascular accidents

Gamma glutamyl transpeptidase (GGTP), glutamic oxaloacetic transaminase (GOT), and glutamic pyruvic transaminase (GPT) were measured serially in the serum and cerebrospinal fluid (CSF) of 22 patients with fresh stroke and an equal number of age- and sex-matched healthy control subjects. It was observed that levels of these enzymes in the CSF of control subjects were very low but were significantly elevated (p less than 0.001) in both serum and CSF in patients with stroke. The elevation was greater in the CSF than in the serum and was maximum during the first four days of stroke. Thereafter, the enzymatic activity declined. Of all these enzymes, GGTP in CSF correlated best with the clinical picture. It was possible to differentiate between the ischemic and hemorrhagic type of stroke on the basis of CSF levels of GGTP (greater than 60.0 units in hemorrhagic stroke). There was no correlation between GGTP levels in CSF and serum or among GOT, GPT, and GGTP in CSF. It can be concluded, therefore, that estimation of GGTP in CSF is helpful not only in predicting the degree of cerebral damage and functional outcome of the patient following stroke but also in differentiating the type of stroke.

Motor responses of autoimmune NZB/B1NJ and C57BL/6Nnia mice to arecoline and nicotine

In 11-13 month C57BL/6Nnia mice, arecoline produced a dose-dependent decrease in motor activity at doses of 0.64-2.5 mg/kg, whereas at doses of 5.0-20.0 mg/kg arecoline produced a dose-dependent increase in motor activity. In marked contrast, age-matched NZB/B1NJ (New Zealand Black) mice failed to exhibit the first phase of the response, but showed a greater dose-dependent increase in motor activity following the doses of 10 and 20 mg/kg. Nicotine, 0.64-2.5 mg/kg, produced a dose-dependent decrease in motor activity in both strains. The effects of arecoline and nicotine were antagonized by scopolamine (2.5 mg/kg) and mecamylamine (1.0 mg/kg), respectively. These findings suggest that muscarinic neurotransmission may be altered in NZB/B1NJ mice, which produce brain-reactive autoantibodies, exhibit learning/memory dysfunctions, and also exhibit a loss of neurons staining positive for choline acetyltransferase.

Anxiety-like subjective effect of ethanol antagonist RO 15-4513 demonstrated in pentylenetetrazol discrimination

Ro 15-4513, a benzodiazepine-receptor ligand which antagonizes ethanol, was tested in the pentylenetetrazol discrimination, a bioassay for anxiogenic drugs. Rats were trained with food reward to discriminate pentylenetetrazol (PTZ) from saline in a two-lever operant task. In lever-selection tests, rats selected the PTZ lever both after PTZ and after Ro 15-4513. The PTZ-like stimulus produced by Ro 15-4513 was blocked by diazepam and by the benzodiazepine receptor blocker Ro 15-1788. Substitution for the anxiogenic drug PTZ, and blockade by the anxiolytic diazepam, support the hypothesis that Ro 15-4513 is anxiogenic; blockade by Ro 15-1788 suggests that the PTZ-like stimulus produced by Ro 15-4513 occurs through its action at the benzodiazepine receptor.

Anxiogenic properties of cocaine withdrawal

Rats were trained to discriminate an injection of pentylenetetrazol (PTZ), 20 mg/kg, from saline using a two-lever operant procedure with food as a reinforcer. In substitution tests, rats selected the PTZ-appropriate lever after PTZ, but not after cocaine (20 mg/kg). A higher dose of cocaine (40 mg/kg) was behaviorally disruptive which resulted in no lever selection during the test session. Subsequently, training and testing were halted, and cocaine, 20 mg/kg/8-hr, was administered for 7 days. Following this chronic drug regimen, substitution of PTZ for the PTZ stimulus was increased. Furthermore, cocaine (40 mg/kg) substituted for the PTZ stimulus. Following redetermination of the PTZ and cocaine dose-response curves, chronic cocaine injections were terminated and spontaneous withdrawal was assessed by determining its substitution for the PTZ stimulus. Cocaine withdrawal progressively substituted for the PTZ stimulus reaching a peak 120 hrs after the last cocaine injection. Diazepam, 5 mg/kg, blocked the PTZ-like stimulus. These data demonstrate that 1) chronic administration of cocaine produced sensitization for the PTZ stimulus, 2) tolerance developed to the behaviorally disruptive effects of cocaine, and 3) cocaine withdrawal produced a PTZ-like stimulus which was blocked by diazepam.

Serum enzymes in head and neck cancer. II. Aliesterase

Serum aliesterase levels have been estimated in 38 patients with head and neck cancer. The mean value was significantly lower than in controls. The decrease in activity was greater in patients with ulcerative growths and it progressed with advancement in the stage of cancer. With radiotherapy, a progressive and significant increase in serum aliesterase activity was observed. In patients with non-malignant growths the activity was comparable with that in controls.

Acute effects of neurogenic stress on urinary electrolyte excretion

Plasma Cortisol and urinary excretion of water, sodium, potassium, calcium and magnesium have been studied in the rat after application of 2 types of neurogenic stress:--(a) tight rubber band tourniquet and (b) electric shock. Plasma cortisol levels increased significantly after application of either type of stress. During both type of stress, there was statistically significant increase in the urinary excretion of water, sodium and calcium but not of potassium and magnesium. Urinary calcium/magnesium ratio was also significantly elevated. The results suggest that stress may be one of the factors involved in the genesis of urolithiasis.