Antidepressant and Neuroprotective Effects of 3-Hydroxy Paroxetine, an Analog of Paroxetine in Rats

BACKGROUND: Paroxetine (PX) is a widely used antidepressant with side effects such as weakness, dizziness, and trouble sleeping. In search of novel compounds with better efficacy and fewer side effects, we synthesized 3HPX, a hydroxylated analog of PX, and compared the 2 in silico for their pharmacokinetic and binding properties and in vivo for their antidepressant and potential neuroprotective effects. METHODS: In silico studies compared pharmacological properties as well as interactions of PX and 3HPX with the serotonin transporter. In vivo studies utilized an animal model of comorbid depression-Parkinson disease. Adult male Wistar rats were injected (sterotaxically) with lipopolysaccharide in the striatum (unilaterally), followed by 14 days of once-daily injections (i.p.) of 10 mg/kg PX or 3HPX. Animals were tested for motor asymmetry and locomotor activity as well as indices of anhedonia and helplessness using sucrose preference and forced swim tests, respectively. Brains of these animals were collected after the last test, and tyrosine hydroxylase–positive neurons in substantia nigra pars compacta and Iba-1–positive stained microglia in ipsilateral striatum were measured. RESULTS: In silico findings indicated that 3HPX could bind stronger to serotonin transporter and also have a better clearance and hence less toxicity compared with PX. In vivo results revealed a more effective reversal of immobility in the swim test, substantial increase in tyrosine hydroxylase–positive cells in the substantia nigra pars compacta, and more ramified Iba-1(+) cells by 3HPX compared with PX. CONCLUSION: The findings suggest superior effectiveness of 3HPX as an antidepressant and neuroprotectant compared with PX and hence potential utility in Parkinson disease depression co-morbidity.