Preclinical Screening for Treatments for Infantile Spasms in the Multiple Hit Rat Model of Infantile Spasms: An Update

Abstract

Infantile spasms are the typical seizures of West syndrome, an infantile epileptic encephalopathy with poor outcomes. There is an increasing need to identify more effective and better tolerated treatments for infantile spasms. We have optimized the rat model of infantile spasms due to structural etiology, the multiple-hit rat model, for therapy discovery. Here, we test three compounds administered after spasms induction in the multiple hit model for efficacy and tolerability. Specifically, postnatal day 3 (PN3) male Sprague-Dawley rats were induced by right intracerebral injections of doxorubicin and lipopolysaccharide. On PN5 p-chlorophenylalanine was given intraperitoneally (i.p.). Daily monitoring of weights and developmental milestones was done and rats were intermittently video monitored. A blinded, randomized, vehicle-controlled study design was followed. The caspase 1 inhibitor VX-765 (50–200mg/kg i.p.) and the GABAB receptor inhibitor CGP35348 (12.5–100mg/kg i.p.) each was administered in different cohorts as single intraperitoneal injections on PN4, using a dose- and time-response design with intermittent monitoring till PN5. 17β-estradiol (40ng/g/day subcutaneously) was given daily between PN3-10 and intermittent monitoring was done till PN12. None of the treatments demonstrated acute or delayed effects on spasms, yet all were well tolerated. We discuss the implications for therapy discovery and challenges of replication trials.

Acquired parvalbumin‐selective interneuronopathy in the multiple‐hit model of infantile spasms: A putative basis for the partial responsiveness to vigabatrin analogs?

“…For example, 17β‐estradiol given daily between PN3 and 10, but not at later developmental periods, to Arx (GCG) 10+7 mice prevents spasms and epilepsy expression and restores interneuronal deficits . However, in the DLP model, a similar treatment with 17β‐estradiol (PN3–10) had no effect on spasms, suggesting different etiopathogenic mechanisms …”

“…Laboratory rodent diet 5,001 (Labdiet, St. Louis, MO, U.S.A.) and water were provided ad libitum to the dam. The rats assigned to the multiple‐hit group were subjected to the induction protocol described in reports of our earlier studies to induce spasms . Briefly, PN3 male rats were stereotactically injected with DOX (5 μg/2.5 μl saline, right intracerebroventricularly) and LPS (3 μg/1.5 μl saline, right intraparietal) under isoflurane anesthesia (Henry Schein, Melville, NY, U.S.A.) .…”

“…Sham‐operated rats received vehicle injections instead of LPS, DOX, or PCPA, and were bred and handled similarly to their DLP littermates. Video‐monitoring was performed on a daily basis between 10:00 and 12:00 and 14:00 and 16:00, from PN3 to PN19 to confirm the presence of spasms in the DLP group and their absence in the sham rats, as described previously . Chemicals were purchased from Sigma‐Aldrich (St. Louis, MO, U.S.A.).…”

“…All of the experimental protocols used were approved by the Albert Einstein College of Medicine Institutional Animal Care and Use Committee, and all procedures and experiments were in accordance with the guidelines The rats assigned to the multiple-hit group were subjected to the induction protocol described in reports of our earlier studies to induce spasms. [13][14][15][16]19,33 Briefly, PN3 male rats were stereotactically injected with DOX (5 lg/2.5 ll saline, right intracerebroventricularly) and LPS (3 lg/1.5 ll saline, right intraparietal) under isoflurane anesthesia (Henry Schein, Melville, NY, U.S.A.). 13,14,16,19,33 On PN5, rats received 200 mg/kg PCPA in saline, i.p.…”

“…[13][14][15][16]19,33 Briefly, PN3 male rats were stereotactically injected with DOX (5 lg/2.5 ll saline, right intracerebroventricularly) and LPS (3 lg/1.5 ll saline, right intraparietal) under isoflurane anesthesia (Henry Schein, Melville, NY, U.S.A.). 13,14,16,19,33 On PN5, rats received 200 mg/kg PCPA in saline, i.p. Controls underwent the same housing conditions but were not exposed to surgery or handling for monitoring.…”