Effects of repeated treatment with monoamine-transporter-inhibitor antidepressants on pain-related depression of intracranial self-stimulation in rats.
Psychopharmacology (Berl) 2020;
237:2201-2212. [PMID:
32382785 PMCID:
PMC7308219 DOI:
10.1007/s00213-020-05530-y]
[Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 04/17/2020] [Indexed: 12/20/2022]
Abstract
RATIONALE
Synaptic neurotransmission with dopamine (DA), norepinephrine (NE), and serotonin (5-HT) is terminated primarily by reuptake into presynaptic terminals via the DA, NE, and 5-HT transporters (DAT/NET/SERT, respectively). Monoamine transporter inhibitors constitute one class of drugs used to treat both depression and pain, and therapeutic effects by these compounds often require repeated treatment for days or weeks.
OBJECTIVES
The present study compared antinociceptive effects produced by repeated treatment with monoamine transporter inhibitors in a preclinical assay of pain-related depression of positively reinforced operant responding.
METHODS
Adult Sprague-Dawley rats equipped with microelectrodes targeting a brain-reward area responded for pulses of electrical brain stimulation in an intracranial self-stimulation (ICSS) procedure. Intraperitoneal injection of dilute lactic acid served as a noxious stimulus that repeatedly depressed ICSS and also produced weight loss during 7 days of repeated acid administration.
RESULTS
Acid-induced depression of both ICSS and body weight were completely blocked by repeated pretreatment with the nonsteroidal anti-inflammatory drug ketorolac. The DAT-selective inhibitor bupropion also fully blocked acid-induced ICSS depression and weight loss throughout all 7 days of treatment. The NET-selective inhibitor nortriptyline and the SERT-selective inhibitor citalopram were generally less effective, but both drugs blocked acid-induced ICSS depression by the end of the 7-day treatment. Acid-induced depression of ICSS and body weight were not blocked by the kappa opioid receptor (KOR) agonist U69593 or the KOR antagonist norbinaltorphimine.
CONCLUSIONS
These results support effectiveness of bupropion to alleviate signs of pain-related behavioral depression in rats and further suggest that nortriptyline and citalopram produce significant but less reliable effects.
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