Acute Impact of Selected Pyridoindole Derivatives on Fos Expression in Different Structures of the Rat Brain

Abstract

The impacts of three pyridoindole derivatives (PDs), designated as PD144, PD143, and PD104, which have previously been shown to have antidepressant (PD144) and anxiolytic (PD143, PD104) properties, were investigated on the Fos expressions in 11 different rat brain areas, including the medial prefrontal cortex, striatum, septum, accumbens nucleus (shell, core), bed nucleus of the stria terminalis, hypothalamic paraventricular nucleus, central amygdala, locus coeruleus, dorsal raphe nucleus, and the solitary tract nucleus. Control rats received vehicle, while the other three groups the PDs in a dose of 25 mg/kg/b.w. The animals were transcardially perfused with a fixative 90 min after the treatments. Coronal sections of 40-µm thickness were processed for Fos-immunostaining by avidin-biotin-peroxidase complex and visualized by nickel-intensified diaminobenzidine complex. Fos-labeled sections were counterstained with neuropeptides including corticoliberine (CRH), oxytocin (OXY), vasopressin (AVP), and vasoactive intestinal polypeptide (VIP) and processed for immunofluorescence staining using Alexa Fluor 555 dye. In all the three groups of animals, the upregulation of PDs-induced Fos expression only in 2 of 11 brain areas was investigated, namely, in the hypothalamic paraventricular nucleus (PVN) and the central amygdaloid nucleus (CeA). The other brain structures studied were devoid of Fos expression. Counterstaining of the Fos-labeled CeA-containing sections with VIP antibody revealed that the Fos expression stimulated by the PDs was upregulated in all the CeA subdivisions (lateral, ventral, capsular), except the medial one. Dual immunoprocessings showed Fos/CRH-labeling in both the PVN and the amygdala and Fos/OXY in the PVN. No Fos/AVP colocalizations were seen in the PVN. The obtained data provide the first view on the intracerebral effects of three new PDs derivatives, which effects were restricted only to the PVN and CeA areas. The present data may help to improve our understanding of the impact of the selected PDs on the brain and to anticipate possible behavioral and neuroendocrine consequences.

Combined <em>in silico,</em> <em>ex vivo</em>, and <em>in vivo</em> Assessment of L-17, a Thiadiazine Derivative With Putative Neuroprotective and Antidepressant-Like Effects

“…It has indeed been reported that various CNS drugs, such typical [12] and atypical antipsychotics [12-14], tricyclic antidepressants [13], and selective 5-HT reuptake inhibitors (SSRIs) [13,15,16], increased c-Fos immunoreactivity in the amygdala, indicating an increased neural excitability in this brain area. In our previous studies, we have found that pyridoindole derivate SMe1EC2M3, a molecule with putative 5-HT reuptake inhibition properties and antidepressant-like behavioral effect [7], stimulated amygdaloid c-Fos immunoreactivity, as well [11]. The fact that SSRIinduced amygdaloid c-Fos immunoreactivity was potentiated by an antagonist of 5-HT1A autoreceptors indicated that 5-HT system is involved in the modulation of amygdaloid neural excitability by antidepressant drugs.…”

“…twenty-four and one hour before immunoreactivity measurements. C-Fos expression was analyzed, as we have reported previously [11,40]. The rats were anesthetized by a combined treatment of zoletil (30 mg/kg, Virbac, Carros, France) and xylariem (15 mg/kg, Riemser Germany) in the volumes of 0.1 ml and 0.24 ml/300 g b.w., respectively.…”

“…Next, the PB rinsing was followed by incubation with the avidin-biotin-peroxidase complex (1:250) for 90 min at RT. After several washings in 0.05 M sodium acetate buffer (SAB, pH 6.0), c-Fos-antigenic sites were visualized by 3,3′-diaminobenzidine tetrahydrochloride (0.0625% DAB) enhanced with 2.5% nickel chloride (Sigma-Aldrich, Germany), in The topographic mapping of the c-Fos protein immunolabeled cells was performed in three brain areas (PFC, hippocampus, and central nucleus of the amygdala) identified based on the rat brain atlas [11,41]. The individual structures investigated were captured unilaterally from 6-10 representative sections using an Axio-Imager A1 light microscope (Carl Zeiss, Jena) coupled to a video camera and monitor.…”

“…Immunohistochemical assessment of proto-oncogene Fos across the brain is an ex vivo experimental technique used for the investigation of mechanism of action of novel CNS drugs. The activation of the proto-oncogene Fos, resulting in an increased expression of its protein product c-Fos, is a well-established marker for the neuronal excitability within the specific brain area [8][9][10][11].…”

Significance of the Stress Research: “In Memoriam, Richard Kvetnansky”

“…They include clinical studies on the neuroendocrine response to stressors (Kapsdorfer et al 2017), the role of genetic factors in rheumatoid arthritis (Vernerová et al 2017), and the response to stressors in patients affected by multiple sclerosis . Preclinical studies include alterations in coronary activity (Lazuko et al 2017) in animal models of post-traumatic stress disorder, potentiation of inflammatory responses by repeated stress , the association of stress with immunomodulatory mechanisms (Vargovič et al 2017), and a report of novel antianxiety and antidepressant compounds with central activity (Koprdova et al 2017).…”