Physiologic effects of maternal separation on rat brain neurochemistry: comparative study

Exposure to maternal separation in early life is associated with alteration in the neuroendocrine and neurotransmitter system which may be associated with risk of psychiatric disorders development at adulthood. The aim of this study was to [i] assess levels of monoamines [dopamine, nor-epinephrine, epinephrine and serotonin] in rat pup's brain following repeated maternal separation [RMS] and maternal deprivation [MD]. [ii] Assess brain corticosterone and oxytocin level following both RMS and MD. This study was carried out on 50 male rat pups divided into 3 experimental groups; Group I: 20 rats subjected to 3 h of repeated maternal separation for 14 days; Group II: 20 rats subjected to 24 h of maternal deprivation; Group III: 10 rats served as control group. At the end of the experimental period, all rats were sacrificed and their brains were rapidly removed and dissected for estimation of monoamines, corticosterone and oxytocin. Brain corticosterone level showed marked increase after both separation procedures, however, MD was associated with marked increase. RMS was associated with higher level of epinephrine, norepinephrine, dopamine and serotonin. Dopamine and serotonin levels however, were reduced after MD. Oxytocin level showed marked reduction after MD and RMS. The current work provided some neurobiological evidence supporting the determinant role of mother-infant relationship in the development of psychopathology. Maternal separation leads to profound alterations in the central neurotransmitter system and therefore is associated with increased risk of psychiatric disorders as depression and anxiety. Moreover, maternal separation has impact on the corticosterone and oxytocin release in the brain. Different separation procedures however, can influence the consequences of MS

Neurotransmitter transports: new insights into structure, function and pharmacology

Neurotransmitter transporters on neurons and glial cells catalyze the uptake of neurotransmitter, and may serve to limit the activation of receptors during synaptic signaling. Over the past few years significant progress has been made toward a molecular understanding of neurotransmitter transporters in the CNS. The plasma membrane neurotransmitter carriers are comprised of two structurally- and mechanistically-distinct gene families, the Na+ and Cl -dependent transporters that include the carriers for most of the classical CNS neurotransmitters and several additional carriers for amino acids and other substrates outside the nervous system. A second structurally distinct family of Na+ -dependent carriers encompasses the excitatory amino acid transporters. For both carrier families the transport of substrate is coupled to the cotransport of sodium ions down a concentration gradient. Electrophysiological studies of neurotransmitter transporters indicate that many of the carriers are electrogenic and may operate in some ways similar to ion channels. In addition, emerging data indicate that these carriers not only function in the uptake of neurotransmitter, but also that as a consequence of their ability to alter the membrane potential they may have a broader role in regulating neuronal excitability and signaling mechanisms.