Table 4.

Summary of the Effects of High/Continuous Doses of Naltrexone on Postnatal Development of the Rat Brain when Administered Directly (with One Exception of Maternal Administration)

Reference	Daily Dose (mg/kg)	Route of Admin.	Duration of Drug Exposure	Age of Offspring when Evaluated (days)	Developmental Effects (Compared to Controls)
[422]	50	s.c.	Birth until 21 days postnatal	21	Greater brain & cerebellar wet weights. Thickersomatosensory cortex. Cerebellum total area larger.More glial cells & granule neurons.
[423]	50	s.c.	Birth until 21 days postnatal	21	Increased brain wet weight.
[425]	3 (3 times daily), 20, 50 or 100	s.c.	Birth until 21 days postnatal	21	Increased brain wet weight.
[428]	50	s.c.	Birth until 21 days postnatal	21	Increased brain wet & dry weights.
[429]	50	s.c.	Birth until 21 days postnatal	21	Increase in number of granule cells of dentate gyrus. Increase in cerebral & cortical width & area.
[430]	50	s.c.	Birth until 21 days postnatal	21	Increases in cerebellar surface dimensions, neural cell numbers, density & size.
[431]	50	s.c.	Once on postnatal day 6	6	Increased proliferation (labeling index) in cerebellum.
[133] & [134]	50	s.c.	Birth until 10 days postnatal	10	Increased purkinje cell dendritic length & spine concentration of granule cells.
			Birth until 21 days postnatal	21	Increased cell dendritic length & spine concentration in hippocampus.
[174]	50	i.p.	Once on postnatal day 1	1	Increased proliferation (labelling index) in ganglion cell layer of the retina
[254]	50	Maternal i.p.	Daily throughout gestation	0, 10 & 21	Increased brain dry & wet weights.

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