Treatment of male rats with finasteride, an inhibitor of 5alpha-reductase enzyme, induces long-lasting effects on depressive-like behavior, hippocampal neurogenesis, neuroinflammation and gut microbiota composition
Introduction
Neuroactive steroids are those steroids that modulate the function of the nervous system. They are important physiological neuromodulators and include steroids synthesized in the peripheral glands as well as those directly produced by the nervous tissue. Neuroactive steroids are involved in the neuroendocrine control of reproduction and regulate synaptic plasticity, neuronal and glial morphology, adult neurogenesis, myelination and cognition (Galea, 2008; Melcangi et al., 2016). Accordingly, psychiatric disorders, such as depression and anxiety, are associated with altered levels of neuroactive steroids, and particularly of 5α-reduced metabolites of testosterone and progesterone, in plasma and/or cerebrospinal fluid (CSF) (Backstrom et al., 2014; Schule et al., 2014).
Finasteride, an inhibitor of the enzyme 5α-reductase (5α-R), blocks the conversion of testosterone and progesterone, into their 5α-reduced metabolites (dihydrotestosterone, DHT, and dihydroprogesterone, DHP, respectively). For this reason, this drug is used for the treatment of benign prostatic hyperplasia (BPH) and androgenetic alopecia (AGA). Indeed, these disorders are associated with high levels of DHT in prostate and in hair follicles of BPH and AGA patients, respectively. By inhibiting 5α-R activity, finasteride reduces DHT levels in prostate and in hair follicles and improve the conditions of BPH and AGA (Traish et al., 2015).
Despite of the wide therapeutic use of finasteride in humans, its effects in the nervous system have been poorly explored. That is particularly important, because a subset of men taking finasteride for AGA show during the treatment a wide symptomatology including depression, erectile dysfunction, endocrine alterations and musculoskeletal manifestations (Giatti et al., 2018). Moreover, as self-reported by the patients (Altomare and Capella, 2002; Irwig, 2012; Rahimi-Ardabili et al., 2006; Traish et al., 2015) and as recently ascertained by two different clinical studies, these important side effects may persist even after discontinuation of the treatment (Basaria et al., 2016; Melcangi et al., 2017). Thus, these patients are affected by the so called post-finasteride syndrome (PFS). In particular, as reported by Basaria and collaborators, PFS patients have impaired sexual function as well as high depression scores (Basaria et al., 2016). In sixteen PFS male patients, we recently observed that 1) all patients showed erectile dysfunction, 2) four of them had altered peripheral neurogenic control of erection and 3) eight of them suffered from a DSM-IV major depressive disorder (Melcangi et al., 2017).
In addition, in plasma and CSF of PFS patients, suspension of drug treatment did not only lead, as expected, to an alteration of 5α-reduced metabolites of testosterone and progesterone, but also to a global alteration of neuroactive steroid levels (Caruso et al., 2015; Melcangi et al., 2013, 2017). Interestingly, observations obtained in male rats indicate that finasteride treatment and its suspension not only alters the levels of neuroactive steroids in plasma and CSF, but also in the brain tissue. However, it is important to note that the effects in plasma or CSF are different in comparison to what observed in brain areas. For instance, subchronic treatment with finasteride (i.e., for 20 days) induced only an increase of progesterone in the hippocampus, while in plasma only an increase in isopregnanolone (i.e., a metabolite of DHP) associated with a decrease in DHT were observed (Giatti et al., 2016). At the withdrawal (i.e., after one month of suspension) a decrease of pregnenolone (i.e., the first neuroactive steroid synthesize from cholesterol) and progesterone associated with an increase of DHP were observed in the hippocampus, while a decrease in progesterone, tetrahydroprogesterone, THP (i.e., a metabolite of DHP), DHT and 3α-diol (i.e., a metabolite of DHT) was observed in plasma (Giatti et al., 2016). Interestingly, neither subchronic treatment with finasteride nor its withdrawal were able to affect the levels of DHT in the hippocampus (Giatti et al., 2016). In addition, the brain changes in neuroactive steroid levels were coupled with altered expression of their receptors, suggesting an altered brain steroid signaling (Giatti et al., 2016).
Depression is a multifaceted psychiatric condition, where genetic susceptibility and environmental factors crosstalk to generate a distressing condition. As reported in humans and in animal models that mimic this condition, depression is characterized by decreased content of neurotransmitters and neurotrophic factors, increased inflammation and gliosis, decreased neurogenesis and neuron survival and mitochondrial impairment (Blier, 2013; Masi and Brovedani, 2011).
Gut microbiota is an exclusive combination of different organisms, such as bacteria, viruses, archaea, protozoa and fungi that interact in a bidirectional way with the central nervous system forming the so call microbiome-gut-brain axis (Mayer, 2011; Sharon et al., 2016). Immune, neural, endocrine and metabolic pathways are included in this axis. Among them, steroid hormones have also an important role. Indeed, several observations indicate that steroid hormones influence gut microbiota niches (Tetel et al., 2018). For instance, gonadectomy or steroid treatment affect the composition of gut microbiota in rodents (Org et al., 2016). Several recent observations seem also to suggest a link between gut microbiota and development and/or manifestation of neuropsychiatric disorders, such as depression and anxiety (Borgo et al., 2017; Foster and McVey Neufeld, 2013). Indeed, microbiota composition is altered both in animal models and in patients with this symptomatology (Hoban et al., 2016; Kelly et al., 2016).
On this basis, our main hypothesis is that treatment with finasteride and/or its withdrawal in male rat may induce depressive-like behavior related with cellular and/or molecular alterations in hippocampus and/or gut microbiota composition. Therefore, in the present study we will explore: (1), whether subchronic treatment with this inhibitor of the enzyme 5α-R induces depressive-like behavior in male rats; (2), whether this alteration persists by 1 month after the end of the treatment and (3), whether finasteride treatment and/or withdrawal is associated with modifications in neurogenesis, gliosis and neuroinflammatory parameters in the hippocampus and with changes in gut microbiota.
Section snippets
Animals and treatments
Male Sprague Dawley rats (250–275 g at arrival, Janvier Labs, Le Genest- Saint-Isle, France) were housed in the animal care facility of the Instituto Cajal, C.S.I.C., Madrid, Spain. All animals were kept in standard rat cages with food and tap water available ad libitum and under controlled humidity and temperature. The rats were acclimated to the new environment for 7 days before being randomly assigned to one of the experimental groups described below. All procedures for handling and killing
Forced swim test
Two-way ANOVA revealed a significant effect of treatment (F = 4.22, p = 0.0474) (Fig. 1). At the end of the treatment, no significant differences were detected in the immobility time in the Porsolt test between animals treated with vehicle or finasteride, neither in pre-test session (day 1, data not shown) or test session (day 2). However, as reported in Fig. 1, one month after withdrawal animals treated with finasteride showed a significantly higher immobility time in the Porsolt test
Discussion
The findings of the present study indicate that finasteride treatment has persistent effects on depressive-like behavior in young adult male rats. To assess depressive-like behavior we used the Porsolt forced swim test (Castagne et al., 2011). Immobility floating behavior in this test is decreased by antidepressant drugs and is considered a manifestation of helplessness (Castagne et al., 2011). In the forced swim test (as the tail suspension test, the foot shock or any other learned
Conclusion
In summary, our findings indicate that finasteride treatment causes several alterations in the hippocampus that are detected at the end of the treatment, such as increased proliferation in the subgranular zone of the dentate gyrus, increased number of astrocytes in the hilus and increased mRNA levels of TNF-α. In addition, other changes are detected by one month after finasteride withdrawal, including decreased proliferation in the subgranular zone, increased astrogliosis in the hilus and a
Contributors
Silvia Diviccaro performed the treatment of animals, behavioral analysis, immunohistochemistry, morphometric analysis, granule cell density analysis.
Silvia Giatti performed assessment of cytokines by Real time PCR
Francesca Borgo, Elisa Borghi and Matteo Barcella responsible for gut microbiota analysis
Silvia Diviccaro, Francesca Borgo, José Luis Trejo, Luis Miguel Garcia-Segura and Roberto Cosimo Melcangi were responsible for study design and wrote the manuscript.
Financial support
This research was supported by grants from MIUR Progetto Eccellenza. We also thank the Post-Finasteride Foundation for the financial support to R.C. Melcangi; Ministerio de Economía, Industria y Competitividad (MINECO), Spain (grant number BFU2017-82754-R), Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain and Fondos Feder for the financial support to L.M. Garcia-Segura.
Conflicts of Interest
None.
References (59)
- et al.
Allopregnanolone and mood disorders
Prog. Neurobiol.
(2014) - et al.
Patients treated for male pattern hair with finasteride show, after discontinuation of the drug, altered levels of neuroactive steroids in cerebrospinal fluid and plasma
J. Steroid Biochem. Mol. Biol.
(2015) - et al.
TNFalpha disrupts blood brain barrier integrity to maintain prolonged depressive-like behavior in mice
Brain Behav. Immun.
(2018) - et al.
Gut-brain axis: how the microbiome influences anxiety and depression
Trends Neurosci.
(2013) Gonadal hormone modulation of neurogenesis in the dentate gyrus of adult male and female rodents
Brain Res. Rev.
(2008)- et al.
Effects of the histone deacetylase inhibitor sodium butyrate in models of depression and anxiety
Neuropharmacology
(2009) - et al.
Behavioural and neurochemical consequences of chronic gut microbiota depletion during adulthood in the rat
Neuroscience
(2016) Persistent sexual side effects of finasteride: could they be permanent?
J. Sex Med.
(2012)- et al.
The effect of water temperature on immobility in the forced swimming test in rats
Eur. J. Pharmacol.
(1994) - et al.
Altered fecal microbiota composition in patients with major depressive disorder
Brain Behav. Immun.
(2015)