Time-dependent exposure of nicotine and smoke modulate ultrasubcellular organelle localization of dopamine D1 and D2 receptors in the rat caudate-putamen.

The correlation of the subcellular localization of dopamine D(1) and D(2) receptors (DA D(1) R, DA D(2) R) with nicotine addiction has not been studied. We demonstrated the ultrasubcellular organelle localization of DA D(1) and D(2) Rs in the caudate-putamen (CPu) area of rat brain in vivo exposed to nicotine (3 mg/day; oral) and passive cigarette smoking (500 ml each; 3 times/day) for 1, 4, and 12 weeks, respectively. Our results revealed DA D(1) R localization in the presynaptic and postsynaptic dendrites, endocytic vesicles, and secretory granules, and DA D(2) R localization in the presynaptic dendrites and vesicles. DA D(1) R immunogold particles were highly decreased in the secretory granules of CPu, and increased in the postsynaptic area and vesicles after prolonged nicotine and smoking exposures, suggesting the strong influence of long time smoking and nicotine exposures on DA D(1) R subcellular organelle localization. DA D(2) R immunoreactivity was comparatively less changed than that of the DA D(1) R. Western blot analysis also showed the differential expression of DA D(1) and D(2) R proteins upon nicotine and smoking exposures as compared to the untreated controls. Taken together, the results for the first time suggests the execution of addictive behavior of nicotine through modulation of mesolimbic dopaminergic system targeting subcellular organelle of DA D(1) and D(2) Rs in the CPu of adult rat brain that may lead to novel therapeutic approaches related to nicotine's neuropsychological disorders including drug addiction.

Mechanism of lead induced effects on human spermatozoa after occupational exposure.

OBJECTIVES: Occupational lead exposure caused several types of male reproductive impairments in different working populations. In the present study we examined the paint factory workers of active reproductive age and compared the data with the non-occupationally exposed desk job holders taken as control from Bangalore, India. MATERIALS AND METHODS: In the above perspective, sperm cell morphology, morphometery and motile activity were assessed. Routine seminal biochemistry, cell cycle phase analysis of sperm head DNA, estimation of serum reproductive hormones and metal levels in blood and semen were also taken into account. RESULT: Low sperm velocity, ATPase activity, gross and forward progressive motility with high stationary motile spermatozoa revealed lowering of cellular activity after lead exposure (p<0.001), which was supported by high seminal plasma fructose level (p<0.001). Lowering of seminal plasma total protein with concomitant rise in free amino acid level was prevalent as the exposure increased (p<0.001), suggesting disturbance in cellular nutritional support essential for cellular motility. Prolonged liquefaction time, reduced semen volume and viscosity as well as altered seminal plasma protein, fructose and cholesterol level among the workers indicated dysfunction of accessory sex glands viz. prostate and seminal vesicle after occupational lead exposure (p<0.001). Deterioration of sperm count, structural abnormality of spermatozoa and sperm head DNA hyploidy was also associated with high blood and semen lead levels in the paint factory workers (p<0.001) without interfering serum FSH, LH and testosterone level (non-significant at p<0.05). CONCLUSION: Therefore, the present study suggested that at the present exposure level lead might cross blood-testis-barrier and increased its value in semen of the occupationally exposed paint factory workers in Bangalore, India, thereby producing detrimental effects on semen quality and sperm characteristics.

Inorganic lead exposure in battery and paint factory: effect on human sperm structure and functional activity.

Lead is one of the industrially important heavy metals that causes male reproductive impairment among battery and paint factory workers, but information on the structure-function integrity of human spermatozoa is still limited. Therefore, it was necessary to investigate the effect of lead on sperm structure and functional activity in these workers. Oligozoospermia with concomitant lowering of sperm protein and nucleic acid content and the percentage of sperm DNA hyploidy (P <0.001) suggested the diminution of sperm cell production after occupational lead exposure. Low sperm vitality and hypoosmotic swelling percentage along with high malondialdehyde content and altered seminal plasma ascorbate level (P<0.001) indicating damage of sperm cell surface, might be due to high membrane lipid peroxidation and failure of non-enzymatic antioxidant protection after lead exposure. Alteration of sperm membrane surface was also evidenced from scanning electron microscopy and further authenticated by atomic and lateral force microscopy. Lowering of sperm velocity, gross and forward progressive motility with high stationary motile spermatozoa (P<0.001) suggested retarded sperm activity among the exposed workers, which was supported by high seminal plasma fructose level and reduced activity of sperm ATPase (P < 0.001). Increased incidence of teratozoospermia was also associated with high blood and semen lead level (PbB, PbS) (P<0.001). Therefore, the results suggested that lead not only affects the sperm count, but also damages the sperm structure and membrane integrity, motility and functional activity among the battery and paint factory workers.

In vivo and in vitro ethanol exposure in prenatal rat brain: GABA(B) receptor modulation on dopamine D(1) receptor and protein kinase A.

We have investigated the effects of prenatal ethanol exposure on GABA(B) receptors (GABA(B)Rs), protein kinase A (PKA), and DA D(1) receptor (DAD(1)R) expressions. GABA(B1)R and GABA(B2)R showed different age-dependent expressions in in vivo fetal rat forebrain from gestational days (GD) 15.5 to 21.5 upon 10% ethanol treatment to mother, with and without baclofen at a dose of 10 mg/kg body weight/day. The protein level changes could not be attributed to changes in the level of transcription since GABA(B)R mRNA presented different expression patterns upon in vivo ethanol treatment. Using in vitro cultivated cortical neurons from GD 17.5 fetuses, we also explored the modulatory effects of ethanol on PKA and DAD(1)R through GABA(B)Rs, under 50 microM baclofen and 100 microM phaclofen administrations, with or without 100 mM of ethanol treatment in the culture media. The results showed that 20 min ethanol treatment without baclofen or phaclofen had increasing effects on both the GABA(B)Rs. Further, baclofen and phaclofen administration significantly affected PKA and GABA(B)R levels upon 20 min and 1 h ethanol treatment. In contrast, DAD(1)R showed increasing effects upon ethanol treatment, which was modulated by GABA(B)R's agonist baclofen and antagonist phaclofen. Therefore the present study suggested that the GABA(B)R activity could modulate ethanol's cellular effects, which possibly including PKA and DAD(1)R activities, and may be an underlying cause of ethanol's effects.