Effects of gestational and breastfeeding caffeine exposure in adenosine A1 agonist-induced antinociception of infant rats.

OBJECTIVES: Caffeine is extensively consumed as a psychostimulant drug, acting on A1 and A2A adenosine receptors blockade. Chronic exposure to caffeine during gestation and breast-feeding may be involved in infant rat's behavioral and biochemical alterations. Our goal was to evaluate the effect of chronic caffeine exposure during gestation and breast-feeding in the functionality of adenosine A1 receptors in infant rats at P14. NTPDase and 5'-nucleotidase activities were also evaluated. METHODS: Mating of adult female Wistar rats was confirmed by presence of sperm in vaginal smears. Rats were divided into three groups on the first day of pregnancy: (1) control: tap water, (2) caffeine: 0.3 g/L until P14, and (3) washout caffeine: caffeine was changed to tap water at P7. Evaluation of nociceptive response was performed at P14 using hot plate (HP) and tail-flick latency (TFL) tests. A1 receptor involvement was assessed using caffeine agonist (CPA) and antagonist (DPCPX). Enzymatic activities assays were conducted in the spinal cord. RESULTS: Gestational and breastfeeding exposure to caffeine (caffeine and washout groups) did not induce significant alterations in thermal nociceptive thresholds (HP and TF tests). Both caffeine groups did not show analgesic response induced by CPA when compared to the control group at P14, indicating chronic exposure to caffeine in the aforementioned periods inhibits the antinociceptive effects of the systemic A1 receptor agonist administration. No effect was observed upon ectonucleotidase activities. CONCLUSIONS: Our results demonstrate that chronic caffeine exposure in gestational and breastfeeding alters A1-mediated analgesic response in rats.

Morphine exposure and maternal deprivation during the early postnatal period alter neuromotor development and nerve growth factor levels.

The objective of this study was to verify whether repeated morphine administration and maternal deprivation in early life alter neurobehavioral development and central nerve growth factor (NGF) levels. A total of 58 male Wistar rat pups were used in our study. From postnatal day 1 (P1), litters were daily deprived of their mother for 3h; this was continued for the first 10days of life. Animals were divided into 5 groups: total control (C), did not receive any intervention; saline (S), received saline solution; morphine (M), received morphine; deprived-saline group (DS), were subjected to maternal deprivation and received saline solution; and deprived-morphine (DM), were subjected to maternal deprivation and received morphine. From P8, newborns received subcutaneous (s.c.) injections of morphine or saline (5µg) once daily for 7days. Righting reflex, negative geotaxis and gait were chosen as postural parameters to evaluate neuromotor reflexes. In the righting reflex test, a delay in the development of animals was evidenced in the M group. Performance of negative geotaxis was slower in the M and DM groups. In the gait test, all groups showed a daily improvement in performance in terms of locomotion frequency. An increased frequency of rearing was observed in the M, DS, and DM groups from P16 to P20. The DM group presented an increase in NGF levels in the brainstem. An increase in cerebral cortex NGF levels in the M, DS, and DM groups was observed as well. Our results suggest that changes in environmental conditions and the disruption of mother-infant interactions during the neonatal period can produce changes in the neurobiology, physiology, and emotional behavior of rats. This finding has important implications for the maternal-neonate interaction needed for normal brain development in newborns.