Table 1.

Selective loss of α₅-subunit immunoreactivity in dendritic layers of the hippocampus in α₅(H105R) mice

Region	α5-subunit immunoreactivity
	OD wild type	OD mutant	%	P
CA1, s. or	219  ± 26	141  ± 34	−36	<0.001
CA1, s. pyr	259  ± 25	215  ± 40	−17	NS
CA1, s. rad	244  ± 19	158  ± 34	−35	<0.001
CA1, s. lm	208  ± 18	133  ± 25	−36	<0.001
CA3, s. or	237  ± 22	170  ± 35	−28	<0.001
CA3, s. pyr	227  ± 26	198  ± 36	−13	NS
CA3, s. lucidum	141  ± 27	99  ± 18	−30	<0.001
CA3, s. rad	289  ± 32	182  ± 31	−37	<0.001
DG, granule cell layer	185  ± 36	173  ± 28	−7	NS
DG, s. mol	184  ± 27	142  ± 31	−23	NS
DG, hilus	89  ± 28	74  ± 19	−18	NS
Olfactory bulb, gcl	164  ± 42	138  ± 29	−16	NS
Striatum	40  ± 10	35  ± 14	−12	NS
Frontal cortex, I–III	17  ± 11	18  ± 13	+3	NS
Frontal cortex, VI	108  ± 31	125  ± 27	+15	NS
Superior colliculus	73  ± 23	57  ± 14	−22	NS
Vs, pars caudalis	97  ± 14	108  ± 22	+12	NS

Densitometry was performed in sections processed for immunoperoxidase staining (adult mice, n = 8 per genotype). For each region, two sections were analyzed per animal; background was measured in the fornix and subtracted. The overall lack of a decrease in α₅-subunit immunoreactivity in the stratum pyramidale (s. pyr.) might represent an increase in intracellular receptors, because membrane-associated α₅GABA_A receptors are reduced in mutant mice (see Fig. 3 d and d′). %, percent deviation from values in wild type. DG, dentate gyrus; OD, optical density values (arbitrary scale); s. lm, stratum laconosum-moleculare; s. lucidum, stratum lucidum; s. mol., stratum moleculare; s. or, stratum oriens; s. rad., stratum radiatum; Vs, spinal trigeminal nucleus. Results are expressed as mean ± SD; NS, not significant (P > 0.05).