Search NEL Online

Comparative Study 2004; 25(4): 267-272 PubMed PMID: 15361815 Citation  Keywords:  Analysis of Variance, Animals, Blood Cell Count, Corticosterone:blood, Hypersensitivity, Delayed:immunology, Immune System:radiation effects, Leukocytes:immunology, Light, Male, Mice, Mice, Inbred C3H, Mice, Inbred C57BL, Photoperiod, Species Specificity,.   

OBJECTIVES: The purpose of this study was to determine whether two different strains of mice, that are reproductively unresponsive to photoperiod, adjust immune function in response to photoperiod.

SETTING AND DESIGN: Adult male C3H/HeN (C3H) and C57BL/6 (C57) mice were each placed into either a long (LD 16:8) or short (LD 8:16) photoperiod for 10 weeks (n = 15/ group).

METHODS: Blood was collected for flow cytometry and radioimmunoassay analysis of leukocyte numbers and corticosterone concentrations, respectively. In addition, all mice were sensitized to, and challenged with the antigen, 2,4-dinitro-1-fluorobenzene. Pinnae measurements were obtained for 7 days following challenge to determine the magnitude of the inflammatory response.

RESULTS: Photoperiod did not affect leukocyte cell numbers in either C3H or C57 mice. C3H mice displayed higher neutrophil numbers than C57 mice (p< 0.0001), whereas C57 mice displayed higher lymphocyte numbers than C3H mice (p< 0.01). C3H mice housed in LD 16:8 had higher corticosterone concentrations than those housed in LD 8:16 (p< 0.005) and C57 mice housed in either photoperiod (p< 0.05). Photoperiod did not affect the inflammatory response, though C57 mice displayed an overall higher magnitude of response than C3H mice (p<0.05).

MAIN FINDINGS: Our results suggest that photoperiod does not alter immune function in C3H and C57 mice. Strain differences in immune function, however, were observed.

CONCLUSIONS: Immune function is unresponsive to photoperiod in these laboratory mice, possibly indicating; a link between immune and reproductive responsiveness to photoperiod, the decreased predictive value of this annual cue to domesticated animals, or both....

Read abstract  Full text PDF

Comparative Study 2004; 25(4): 257-261 PubMed PMID: 15361813 Citation  Keywords:  Adrenergic beta-Agonists:pharmacology, Age Factors, Animals, Circadian Rhythm:drug effects, Isoproterenol:pharmacology, Male, Melatonin:biosynthesis, Organ Culture Techniques, Photoperiod, Pineal Gland:drug effects, Rats, Rats, Wistar, Time Factors,.   

OBJECTIVES: The purpose of this study was to investigate and compare the effects of the beta-adrenergic agonist, isoproterenol, on induced increase in melatonin production in the pineal gland of young and old rats, at different circadian stages.

MATERIALS AND METHODS: We report here the effects of 10(-6) M isoproterenol-stimulated melatonin production by perifused pineal glands obtained from young (55 day old) and old (21 month old) male Wistar rats acclimatised to light:dark cycles regimen of 12:12 for 3 weeks. Pineal glands were collected at different circadian stages: 3, 7, 11, 15, 19 and 23 hours after light onset (HALO), and perifused for 510 min.

RESULTS: The basal levels of melatonin production in the young rats were approximately twice greater than those of the old rats. Isoproterenol stimulated melatonin production in both young and old rat pineal glands, whatever the circadian stage. The intensity of the response to 10(-6) M isoproterenol infusion was greater in young than in old rat pineal glands (P<0.001), with a trend towards an increase during the light phase, at 7 HALO, in both young and old rat pineal glands, although this trend towards increased melatonin response did not reach statistical significance (P>0.05).

CONCLUSIONS: These results show that isoproterenol is able to stimulate both young and old rat pineal glands whatever the circadian stage. The magnitude of isoproterenol stimulation is greater in young than in old glands. Our results also suggest that the pineal gland response to isoproterenol is not dependent on circadian stage, at least, under our experimental conditions....

Read abstract  Full text PDF

Comparative Study 2004; 25(4): 252-256 PubMed PMID: 15361812 Citation  Keywords:  Analysis of Variance, Animals, Free Radicals:analysis, Hydroxyl Radical:blood, Male, Melatonin:physiology, Nitrogen Oxides:blood, Pain:metabolism, Rats, Rats, Wistar, Reactive Oxygen Species:analysis, Serum:chemistry, Singlet Oxygen:blood, Somatosensory C.   

: The concentrations of ROS were measured in samples of the sensorimotor brain cortex and in the rat blood. We measured the following parameters: The six lines spectra, nitroxide radical, free hydroxyl radical and singleton oxygen. Their concentration was measured under physiological conditions, after the nociceptive stimulation and after the application of melatonin, both in normal and stimulated animals. In the brain cortex only the singleton oxygen decreased after the nociceptive stimulation, whereas the nitroxide radicals and six lines spectra increased. The free hydroxyl radicals did not change significantly. In the blood serum the six lines spectra and nitroxide radical increased, the concentration of the free hydroxyl radicals did not change. Melatonin increased both the hydroxyl and nitroxide radicals. There was a non-significant decrease in the six lines spectra. The estimation of ROS can be used as a tool for detecting metabolic changes and the consequences of different environmental influences, in our case the influence of nociception and melatonin....

Read abstract  Full text PDF

Journal Article 2004; 25(3): 219-222 PubMed PMID: 15349089 Citation  Keywords:  Animals, Estradiol:pharmacology, Female, Hypothalamus:enzymology, Rats, Rats, Wistar, Sexual Maturation:physiology, Synaptic Transmission:drug effects,.   

OBJECTIVES: To determine the hypothalamic activity of nitric oxide synthase (NOS, the enzyme involved in the synthesis of nitric oxide NO) during sexual maturation in prepubertal (15 days old) and peripubertal female rats (30 days old) as well as the effect of estradiol administration on this neurotransmitter system.

METHODS: Hypothalamic samples containing the anterior preoptic and medial basal areas (APOA-MBH) were homogenized with HEPES 20 mM, pH = 7.4 and NOS activity was determined in APO-MBH after 10 minutes of incubation by the conversion of 14C arginine to 14C citrulline.

RESULTS: The hypothalamic concentration of NOS is significantly higher in peripubertal than in prepubertal rats. Treatment with EB increased significantly the activity of the enzyme in both groups compared with control and the increases was similar at both ages.

CONCLUSIONS: These results clearly demonstrated that the hypothalamic NOS activity increases in peripubertal rats as compared with prepubertal animals. Estradiol has a similar stimulatory effect on hypothalamic NOS activity at both ages of sexual maturation, indicating that the increase in NOS during sexual maturation is connected with the peripubertal increase of estradiol rather than an increase in the sensitivity of the enzyme to the ovarian hormone....

Read abstract

Journal Article 2004; 25(3): 196-200 PubMed PMID: 15349085 Citation  Keywords:  Acute Disease, Animals, Corticosterone:blood, Encephalomyelitis, Autoimmune, Experimental:blood, Male, Rats, Rats, Wistar, Testosterone:blood, Time Factors,.   

OBJECTIVES: Experimental autoimmune encephalomyelitis (EAE) was induced to investigate the levels of circulating total testosterone (TT) and the possible association of corticosterone with the steroid-producing capacity of the testes.

SETTING AND DESIGN: We determined gonad weights, serum TT and corticosterone levels during the development of EAE in male rats.

METHODS: Active EAE was induced in young male Wistar rats by injection of whole myelin in complete Freund's adjuvant. All the rats were weighted and monitored daily for clinical signs and blooded during different phases of the disease. Serum TT was measured by radioimmunoassay and circulating corticosterone was determined using a competitive enzyme immunoassay. Also testes and seminal vesicles were removed to determine their weights.

RESULTS: Seminal vesicle weights and serum TT levels diminished during the acute stage of the disease in all EAE rats and then they began gradually to increase, reaching the normal values at the post-recovery phase. Concomitantly a significant increase in serum corticosterone levels was observed during the acute EAE and the post-recovery phase was accompanied by a decline in corticosterone levels.

MAIN FINDING: Our results indicated an inverse correlation between serum TT and corticosterone levels during the acute EAE. Moreover, the diminution of TT was not a consequence of an alteration of the testes induced by anti-myelin antibodies neither contributed by apoptosis of testis cells by exposure to corticosterone.

CONCLUSIONS: The negative correlation between corticosterone and TT levels associated to EAE may be relevant in understanding the association of the endocrine system and the development of autoimmune demyelinating diseases....

Read abstract

Journal Article 2004; 25(3): 191-195 PubMed PMID: 15349084 Citation  Keywords:  Animals, Base Sequence, DNA Primers, Female, Gene Expression Regulation, Hypothalamus:physiology, Leptin:genetics, Pituitary Gland:physiology, Polymerase Chain Reaction, Pregnancy, Pregnancy, Animal:physiology, RNA, Messenger:genetics, Swine,.   

BACKGROUND: Leptin, the 16-kDa peptide hormone product of the ob gene, is a regulatory hormone secreted mainly by adipose tissue. Recent studies have shown leptin production by other tissues, including rat hypothalamus, rat and human pituitary, rat skeletal muscle, kidney and stomach, human and porcine placenta, human mammary epithelial cells as well as endometrial tissues. This hormone is a central modulator of food intake, metabolism and neuroendocrine functions.

OBJECTIVES: The aim of the study was to detect and locate porcine leptin gene expression in the different areas of the hypothalamus and pituitary on days 14-16 and 30-32 of pregnancy in pigs.

METHOD: Leptin gene expression was analysed by RT-PCR method. PCR products were subjected to sequencing analysis.

RESULTS: Leptin mRNA was expressed in the medial basal hypothalamus, preoptic area, stalk median eminence, anterior pituitary, posterior pituitary and adipose tissue on days 14-16 and 30-32 of pregnancy. Sequence analysis of the 258 bp product from the hypothalamus and pituitary confirmed 99% homology with the corresponding region of porcine leptin cDNA sequence.

CONCLUSION: Leptin mRNA expression in the porcine hypothalamus and pituitary gland implies its paracrine and/or autocrine role in the regulation of hypothalamic-pituitary axis activity....

Read abstract

Journal Article 2004; 25(3): 184-190 PubMed PMID: 15349083 Citation  Keywords:  Alternative Splicing, Animals, Base Sequence, Bivalvia:genetics, Cilia:drug effects, Enkephalin, Ala(2)-MePhe(4)-Gly(5)-:pharmacology, Ganglia, Invertebrate:drug effects, Genetic Variation, Haloperidol:pharmacology, Molecular Sequence Data, Morphine:pharm.   

OBJECTIVES: The study sought to determine how dopamine controls ganglionic processes involved with modulating lateral cilia beating via the peripheral branchial nerve.

METHODS: The lateral cilia found on the gill filaments exhibit metachronal ciliary beating determined stroboscopically. Novel opiate receptors were determined pharmacologically and demonstrated by RT-PCR and sequence analysis of total RNA from Mytilus edulis visceral ganglia.

RESULTS: Dopamine applied to the visceral ganglion inhibits the activity of lateral cilia in a concentration and haloperidol sensitive manner. Morphine or DAMGO significantly enhances ciliary beating in a naloxone sensitive manner, whereas L-NAME, a nitric oxide synthase inhibitor, only antagonized morphine's action. SNAP, a nitric oxide donor, also enhanced lateral ciliary beating rates. Supporting the observation, i.e., morphine sensitive nitric oxide enhancement of ciliary beating and DAMGO insensitive, that two different mu opiate receptors are present in this tissue, a 602 bp fragment of the human micro 3 opiate receptor and a 935 bp fragment, designated micro 4 have been demonstrated.

CONCLUSIONS: The lateral epithelium of the gill is innervated by serotonergic, cilioexcitatory neurons and dopaminergic, cilioinhibitory neurons, originating in the visceral ganglion. This data supports previous reports that demonstrate inhibiting ganglionic dopamine release allows the serotonin signals to prevail uncontrolled, enhancing ciliary rates. Supporting the observation that two different mu opiate receptors are present in this tissue, evidence is presented that identifies a 602 bp fragment of the human micro 3 opiate receptor and a 935 bp fragment, designated micro 4. Overall, the data strongly suggests that the two alternatively spliced mu opiate receptors may be involved in the physiological regulation of lateral ciliary activity in the visceral ganglia via dopamine and nitric oxide....

Read abstract  Full text PDF

Journal Article 2004; 25(3): 178-183 PubMed PMID: 15349082 Citation  Keywords:  Amines:pharmacology, Analgesics:pharmacology, Animals, Antimanic Agents:pharmacology, Body Weight:drug effects, Cyclohexanecarboxylic Acids:pharmacology, Female, Fertility:drug effects, Follicle Stimulating Hormone:blood, Male, Organ Size:drug effects, Pr.   

PURPOSE: A case control study was conducted to assess the effect of Sabril (Vigabatrin), Lamictal (Lamotrigine) and Neurontin (Gabapentin) on fertility in male rats. Their effect on the body and organs weight and certain biochemical profiles including total serum protein, cholesterol, triglycerides, serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), serum testosterone, and FSH levels were also measured.

METHODS: several parameters, concerning fertility were measured in 40 albino male rats of Sprague Dawley strain, they were divided into 4 groups, group one received vehicle (distilled water), group two received Vigabatrin in a dose of 200 mg/kg body weight, group three received Lamotrigine in a dose of 30 mg/kg body weight, and group four received Gabapentin 100 mg/kg body weight. All the male rats in these groups received the different medications for a complete reproductive cycle (60 days). After 24 hours of the last dose, the animals were weighed and autopsied under light ether anesthesia. Parameter of fertility that has been measured in this study includes: sperm count and motility, weight of different reproductive organs, germ cell and interstitial cell population, serum testosterone and FSH levels and assessment of pregnancies in females mixed with tested males. Biochemical profiles such as serum cholesterol, serum triglycerides, serum bilirubin, SGOT, SGPT level are all measured. The results of the histological, histometerical studies and biochemical profiles were compared to that of the control group, and the significance of these results was measured using student's "t" test.

RESULTS: There was significant reduction in the body weight and the weight of the testes, epididymis, seminal vesicles, ventral prostate, and vas deferens in the antiepileptic fed male rats in comparison to the control group (p > 0.001). There was significant reduction in testicular cells population dynamics including both germinal cell types and interstitial cell types in the antiepileptic fed male rats in comparison to the control group. There was also significant reduction in histometrical parameters and sperm dynamics in the antiepileptic fed male rats histologies in comparison to the control group. There was significant reduction in both testosterone and FSH levels (p < 0.001) in the antiepileptics fed male rats in comparison to the control group. There was also significant reduction in pregnancy rate observed in female rats exposed to the tested male rats among antiepileptic fed male rats compared to controls. The results of biochemical profiles assessment showed significant reduction in serum glucose, serum cholesterol, serum triglycerides levels and significant increase in serum bilirubin, SGOT, and SGPT levels in antiepileptics fed male rats in comparison to the control group.

CONCLUSIONS: Fertility rate and other parameters concerned with fertility, sex hormones and certain biochemical profiles were significantly disturbed in male rats fed with three of the second-generation antiepileptic drugs Vigabatrin, Lamotrigine, and Gabapentin, indicating a possible toxic effect of these three medications on sexual organs, liver, and lipid metabolism....

Read abstract  Full text PDF