The serotonergic and noradrenergic systems of the hippocampus: their interactions and the effects of antidepressant treatments

Differential Role of Galanin Receptors in the Regulation of Depression-Like Behavior and Monoamine/Stress-Related Genes at the Cell Body Level

“…injections resulted in increased activity of the LC NA system, evidenced by an increase of TH and galanin mRNA levels in the LC, in agreement with previous findings (Biguet et al, 1986;Berod et al, 1987;Richard et al, 1988;Austin et al, 1990;Holmes et al, 1995). Stress-induced hyperactivity of the LC neurons and increased release of NA have been proposed to contribute to development of human depression (Nestler et al, 1990; see Mongeau et al, 1997;Grant and Weiss, 2001;Morilak and Frazer, 2004). Importantly, chronic treatment with NA reuptake inhibitors was shown to reduce activation of the LC and exaggerated NA release in response to acute stress, but to increase synaptic levels of NA under basal conditions (Valentino and Curtis, 1991;Morilak and Frazer, 2004;Bondi et al, 2007).…”

“…In agreement, inescapable stress and activation of the galanin system modulate expression of molecules in monoamine circuits involved in coping with stress (see Weiss et al, 1981;Mongeau et al, 1997;Mann, 1999;Maier and Watkins, 2005).…”

“…It is generally assumed that dysfunctional monoaminergic transmission may underlie various symptoms of depression, including the susceptibility to stress (see Heninger et al, 1996;Mongeau et al, 1997;Holsboer, 2001;Morilak and Frazer, 2004). Since galanin and the galanin receptors are expressed in both the NA and 5-HT systems, it is possible that the role of galanin in depression-like behavior may, at least partially, be related to modulation of brain NA and/or 5-HT functions at the cell body level and/or their projection areas.…”

5-HT1A Receptor Function in Normal Subjects on Clinical Doses of Fluoxetine Blunted Temperature and Hormone Responses to Ipsapirone Challenge

“…5-HT 1A receptors are located presynaptically on serotonergic cell bodies in the raphe nuclei where they serve as autoreceptors which inhibit cell firing and reduce 5-HT release by a negative feedback mechanism, and post-synaptically in the hippocampus, cortex and other brain areas, including the hypothalamus. Based on electrophysiological studies in rats, De Montigny and colleagues Mongeau et al 1997) proposed that each major class of antidepressants increases 5-HT neurotransmission by a distinct mechanism involving either pre-or post-synaptic 5-HT 1A receptors. The selective serotonin re-uptake inhibitors (SSRIs), which raise 5-HT synaptic levels when given acutely, were proposed to increase 5-HT transmission on repeated administration by inducing desensitization of somatodendritic 5-HT 1A autoreceptors in the raphe nuclei and nerve terminal 5-HT 1B autoreceptors, which also mediate feedback inhibition of 5-HT release.…”

“…5-HT 1A receptors are located presynaptically on serotonergic cell bodies in the raphe nuclei where they serve as autoreceptors which inhibit cell firing and reduce 5-HT release by a negative feedback mechanism, and post-synaptically in the hippocampus, cortex and other brain areas, including the hypothalamus. Based on electrophysiological studies in rats, De Montigny and colleagues Mongeau et al 1997) proposed that each major class of antidepressants increases 5-HT neurotransmission by a distinct mechanism involving either From the Biological Psychiatry Laboratory, Department of Psychiatry, Hadassah-Hebrew University Medical Center (BL, YG, MEN) and the Laboratory of Applied Statistics, Hebrew University (MG), Jerusalem, Israel; the Endocrine Laboratory, Department of Medicine (BA) and Department of Psychiatry (KPL), University of Wuerzburg, Wuerzburg, Germany.Address correspondence to: Prof. Bernard Lerer, Biological Psychiatry Laboratory, Dept. of Psychiatry, Hadassah-Hebrew University Medical Center, Ein Karem, Jerusalem 91120, Israel.…”