Table 5.

Summary of the Effects of Low/Intermittent Doses of Naltrexone on Postnatal Development of the Rat Brain when Administered Directly

Reference	Daily Dose (mg/kg)	Route of Admin.	Duration of Drug Exposure	Age of Offspring when Evaluated (days)	Developmental Effects (Compared to Controls)
[423]	1	s.c.	Birth until 21 days postnatal	21	Decreased brain wet weight.
[425]	0.1, 1 or 9	s.c.	Birth until 21 days postnatal	21	Decreased brain wet weight.
[428]	1	s.c.	Birth until 21 days postnatal	21	Decreased brain wet & dry weights.
[429]	1	s.c.	Birth until 21 days postnatal	21	Increase in cell density, with decreased macroscopic area of hippocampus. Decreased cerebral area & width.
[430]	1	s.c.	Birth until 21 days postnatal	21	Decreases in cerebellar surface dimensions & density of internal granule cells.
[431]	1	s.c.	Once on postnatal day 6	6	Decreased proliferation (labeling index) in cerebellum.
[134]	1	s.c.	Birth until 10 or 21 days postnatal	10 or 21	Subnormal dendrite length & spine growth, predominant by day 21.

Admin. = administration, s.c. = subcutaneous, and i.p. = intraperitoneal.