Article

Cellular effects of swim stress in the dorsal raphe nucleus.

Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA.
Psychoneuroendocrinology (impact factor: 5.81). 08/2007; 32(6):712-23. DOI:10.1016/j.psyneuen.2007.05.001 pp.712-23
Source: PubMed

ABSTRACT Swim stress regulates forebrain 5-hydroxytryptamine (5-HT) release in a complex manner and its effects are initiated in the serotonergic dorsal raphe nucleus (DRN). The purpose of this study was to examine the effects of swim stress on the physiology of DRN neurons in conjunction with 5-HT immunohistochemistry. Basic membrane properties, 5-HT(1A) and 5-HT(1B) receptor-mediated responses and glutamatergic excitatory postsynaptic currents (EPSCs) were measured using whole-cell patch clamp techniques. Rats were forced to swim for 15min and 24h later DRN brain slices were prepared for electrophysiology. Swim stress altered the resting membrane potential, input resistance and action potential duration of DRN neurons in a neurochemical-specific manner. Swim stress selectively elevated glutamate EPSC frequency in 5-HT DRN neurons. Swim stress non-selectively reduced EPSC amplitude in all DRN cells. Swim stress elevated the 5-HT(1B) receptor-mediated inhibition of glutamatergic synaptic activity that selectively targeted 5-HT cells. Non-5-HT DRN neurons appeared to be particularly responsive to the effects of a milder handling stress. Handling elevated EPSC frequency, reduced EPSC decay time and enhanced a 5-HT(1B) receptor-mediated inhibition of mEPSC frequency selectively in non-5-HT DRN cells. These results indicate that swim stress has both direct, i.e., changes in membrane characteristics, and indirect effects, i.e., via glutamatergic afferents, on DRN neurons. These results also indicate that there are distinct local glutamatergic afferents to neurochemically specific populations of DRN neurons, and furthermore that these distinct afferents are differentially regulated by swim stress. These cellular changes may contribute to the complex effects of swim stress on 5-HT neurotransmission and/or the behavioral changes underlying the forced swimming test model of depression.

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    [show abstract] [hide abstract]
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Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

5-HT DRN neurons
 
5-HT immunohistochemistry
 
5-HT neurotransmission
 
behavioral changes
 
cellular changes
 
complex effects
 
complex manner
 
distinct afferents
 
DRN cells
 
forced swimming test model
 
glutamatergic afferents
 
glutamatergic synaptic activity
 
indirect effects
 
neurochemical-specific manner
 
neurochemically specific populations
 
non-5-HT DRN cells
 
Non-5-HT DRN neurons
 
selectively targeted 5-HT cells
 
Swim stress non-selectively
 
whole-cell patch clamp techniques