Rajashekar Rao Barkur’s research while affiliated with Manipal Academy of Higher Education and other places

Studies in urban children exposed to low lead (Pb) have shown neurobehavioral deficits in the domains of intelligence, reaction time and attention. The structures - hippocampus (vital for learning and memory) and cerebellum (play a role in motor behavior and cognition) - which develop postnatally, are affected by developmental Pb exposure. The effect of low level of Pb exposure during specific periods of early brain development on early neurobehavioral outcomes in rat pups has not been studied. So in this study, pregnant albino Wistar strain rats were exposed to low levels of Pb in drinking water during gestation period (G group), lactation period (L group), both gestation and lactation period (GL group) and prior to pregnancy (a period of 1 month) (PG group). The rat pups born in each of these groups were assessed in preweaning neurobehavioral parameters including surface righting reflex, swimming development, negative geotaxis and ascending wire mesh test. The swimming development scores were low in the GL group of rats. The negative geotaxis score in GL and G groups were altered. The day of achievement of ascending wire mesh test was significantly delayed in GL, G and L groups of rats. To conclude, results show that (a) low level of Pb exposure during gestation and lactation period of brain development causes significant alterations in the early neurobehavioral and sensorimotor reflex development in the absence of concomitant weight loss and (b) gestation period only and lactation period only, Pb exposure causes alteration in some of the neurobehavioral outcomes.

Widespread use of heavy metal lead (Pb) for various commercial purposes has resulted in the environmental contamination caused by this metal. The studies have shown a definite relationship between low level lead exposure during early brain development and deficit in children's cognitive functions. This study investigated the passive avoidance learning and spatial learning in male rat pups exposed to lead through their mothers during specific periods of early brain development. Experimental male rats were divided into 5 groups: i) the normal control group (NC) (N = 12) consisted of rat offspring born to mothers who were given normal drinking water throughout gestation and lactation, ii) the pre-gestation lead exposed group (PG) (N = 12) consisted of rat offspring, mothers of these rats had been exposed to 0.2% lead acetate in the drinking water for 1 month before conception, iii) the gestation lead exposed group (G) (N = 12) contained rat offspring born to mothers who had been exposed to 0.2% lead acetate in the drinking water throughout gestation, iv) the lactation lead exposed group (L) (N = 12) had rat offspring, mothers of these rats exposed to 0.2% lead acetate in the drinking water throughout lactation and v) the gestation and lactation lead exposed group (GL) (N = 12) contained rat offspring, mothers of these rats were exposed to 0.2% lead acetate throughout gestation and lactation. The study found deficit in passive avoidance learning in the G, L and GL groups of rats. Impairment in spatial learning was found in the PG, G, L and GL groups of rats. Interestingly, the study found that gestation period only and lactation period only lead exposure was sufficient to cause deficit in learning and memory in rats. The extent of memory impairment in the L group of rats was comparable with the GL group of rats. So it can be said that postnatal period of brain development is more sensitive to neurotoxicity compared to prenatal exposure. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Epidemiological studies in children have proved that lead (Pb) exposure causes deficits in neural and cognitive functions. The present study assessed the oxidative stress on postnatal day 30, in the hippocampus, cerebellum and frontal cortex of rat pups exposed to Pb during specific periods of early brain development. Five groups of rat pups were investigated, and 0.2 % Pb acetate in drinking was the dosage used. (i) Gestation and lactation (GL) group (n = 9) of rat pups was exposed to Pb during gestation and lactation through their mother, (ii) gestation (G) group (n = 9) of rat pups was exposed to Pb during gestation only, (iii) lactation (L) group (n = 9) of rat pups was exposed to Pb during lactation only, (iv) pre-gestation (PG) group (n = 9) of rat pups was born to mothers who were exposed to Pb for 1 month before conception, and (v) normal control (NC) (n = 9) group of rats pups had no exposure to Pb during gestation and lactation period. From the present study, it is evident that Pb exposure during different periods of early brain development (GL, G, L and PG groups) causes oxidative stress and lactation period (postnatal period) of Pb exposure produces maximum oxidative stress.

Neuropsychological studies in children who are exposed to lead during their early brain development have shown to develop behavioural and cognitive deficit. The aim of the present study was to assess the cellular damage in hippocampus, amygdala and cerebellum of rat pups exposed to lead during different periods of early brain development. Five groups of rat pups were investigated. (a) Control group (n = 8) (mothers of these rats were given normal drinking water throughout gestation and lactation), (b) pregestation lead-exposed group (n = 8) (mothers of these rats were exposed to 0.2% lead acetate in the drinking water for one month before conception), (c) gestation lead-exposed group (n = 8) (exposed to 0.2% lead acetate in the drinking water through the mother throughout gestation [gestation day 01 to day 21]), (d) lactation lead-exposed group (n = 8) (exposed to 0.2% lead acetate in the drinking water through the mother throughout lactation [postnatal day 01 to day 21]) and (e) gestation and lactation lead-exposed group (n = 8) (exposed to 0.2% lead acetate throughout gestation and lactation). On postnatal day 30, rat pups of all the groups were killed. Numbers of surviving neurons in the hippocampus, amygdala and cerebellum regions were counted using cresyl violet staining technique. Histological data indicate that lead exposure caused significant damage to neurons of hippocampus, amygdala and cerebellum regions in all lead-exposed groups except lactation lead-exposed group. The extent of damage to neurons of hippocampus, amygdala and cerebellum regions in lactation lead-exposed group was comparable to gestation and lactation groups even though the duration of lead exposure was much less in lactation lead-exposed group. To conclude, the postnatal period of brain development seems to be more vulnerable to lead neurotoxicity compared to prenatal period of brain development.

Context: According to goal orientation theory, achievement goals are defined as the terminal point towards which one's efforts are directed. The four academic achievement goal orientations commonly recognised are mastery, performance approach, performance avoidance and work avoidance. The objective of this study was to understand the goal orientation of second year undergraduate medical students and how this correlates with their academic performance. Methods: The study population consisted of 244 second year Bachelor of Medicine and Bachelor of Surgery (MBBS) students of Melaka Manipal Medical College, Manipal campus, Manipal University, India. Students were categorised as high performers and low performers based on their first year university examination marks. Their goal orientations were assessed through a validated questionnaire developed by Was et al. These components were analysed by independent sample t-test and correlated to their first year university examination marks. Results: Confirmatory component factor analysis extracted four factors, which accounted for 40.8% of the total variance in goal orientation. The performance approach goal orientation alone explained 16.7% of the variance followed by mastery (10.8%), performance avoidance (7.7%) and work avoidance (5.7%). The Cronbach's alpha for 19 items, which contributed to internal consistency of the tool, was observed to be 0.635. A strong positive correlation was shown between performance approach, performance avoidance and work avoidance orientations. Of the four goal orientations, only the mean scores in work avoidance orientation differed for low performers and high performers (5.0 vs. 4.3; P = 0.0003). Discussion: Work avoidance type of goal orientation among the low performer group may account for their lower performance compared with high performer group. This indicates that academic achievement goal orientation may play a role in the performance of undergraduate medical students.

Low Lead Exposure During Foetal and Early Postnatal Life Impairs Passive Avoidance Learning in Adulthood in Rats This follow-up study investigated the effects of low-level lead exposure during prenatal and early postnatal period on learning and memory in rats immediately after exposure has ceased at weaning and later in their adulthood. Male Wistar-derived rats were exposed to lead (as 0.2 % lead acetate solution) through their mothers during pregnancy and lactation until they were weaned. Mothers of control rats were given tap water during pregnancy and lactation. All pups were weaned on tap water at 21 days of age and were followed up until 120 days old. Low-level lead exposure did not affect their body weight at any time during the experiment. Blood lead in the exposed rats was significantly higher on postnatal day 22 and dropped to control values by day 120. Passive avoidance test showed impaired memory retention in the exposed rats on postnatal days 25 and 120. This suggests that exposure to low-lead levels during foetal and early postnatal development of brain tissue can cause memory impairment that lasts into adulthood.