Maternal Exposure to the Cannabinoid Agonist WIN 55,12,2 during Lactation Induces Lasting Behavioral and Synaptic Alterations in the Rat Adult Offspring of Both Sexes

Perinatal WIN exposure induces a selective deficit in LTD in the PFC of adult offspring. A, A 10-min, 10-Hz field stimulation of layer 2/3 cells in the PFC of the adult offspring of sham-treated dams (N = 14) elicited a robust eCB-LTD at deep layer synapses. However, this same protocol failed to induce eCB-LTD in the adult offspring of dams treat with WIN (N = 14). B, fEPSP magnitude at baseline (−10−0 min) and LTD (35–40 min post-tetanus) values corresponding to the normalized values in A (two-way RM ANOVA, F_(1,24) = 16.58, p = 0.0004; Sidak’s multiple comparisons test, p = 0.0332 and p = 0.9412, respectively). C, LTD mediated by mGlu_2/3 receptors (mGluR-LTD) is not altered in WIN-exposed offspring. mGluR-LTD, induced via a 10-min application of LY379268 (LY; 30 nm), produced a significant depression at deep layer synapses of the PFC in the adult offspring of both sham-treated and WIN-treated dams (N = 12, 12, respectively). D, fEPSP magnitude at baseline (−10−0 min) and LTD (30−40 min postdrug) values corresponding to the normalized values in C. No differences were found between groups comparing the 10-min baseline period and the last 10 min of recording, however both groups exhibited a significant difference of fEPSP magnitude at baseline (i.e., −10−0 min) as compared with 30−40 min postdrug (two-way RM ANOVA, F_(1,11) = 96.69, p < 0.0001; Sidak’s multiple comparisons test, p < 0.0001 for both groups). E, A TBS protocol (five pulses at 100 hz, repeated four times) at layer 2/3 cells in the PFC of the adult offspring of both sham-treated and WIN-treated dams elicited a robust LTP at deep layer synapses (N = 13, 15, respectively). F, fEPSP magnitude at baseline (−10−0 min) and LTP (30−40 min post-TBS) values corresponding to the normalized values in E. Both groups exhibited significant differences between the fEPSP magnitude at 30−40 min as compared with −10−0 min (two-way RM ANOVA, F_(1,25) = 1.737; Sidak’s multiple comparisons test, p < 0.0001 for both groups); *p < 0.05.

Perinatal WIN exposure does not alter properties of intrinsic excitability of deep layer pyramidal neurons in the PFC of adult offspring. A, Current injection steps of 50 pA from –400 to 150 pA revealed no differences in the I-V relationship in pyramidal neurons of the PFC between the adult offspring of sham-treated and WIN-treated dams (N = 12, 13, respectively). B, Action potentials elicited by progressive current injections from 0 to 600 pA revealed no difference in the number of spikes elicited in pyramidal neurons of the PFC in slices obtained from the adult offspring of WIN-injected dams as compared with those from sham-treated dams (N = 13, 12, respectively; two-way RM ANOVA, F_(20,460) = 1.112, p = 0.3328). C, Progressive current injections in 10-pA steps from 0 to 200 pA revealed that the minimum current injection required to elicit an action potential (i.e., rheobase) did not differ in deep layer pyramidal neurons of PFC slices obtained from the adult offspring of WIN-treated, as compared with sham-treated, dams (N = 13, 12, respectively; two-tailed t test, p = 0.1896). D, Similarly, no difference was found in the resting membrane potential of deep layer pyramidal cells in PFC slices obtained from the adult offspring of WIN-treated dams, as compared with those obtained from sham-treated dams (N = 13, 12, respectively; two-tailed t test, p = 0.1123); *p < 0.05.

Perinatal WIN exposure abolishes LTD in the NAc of adult offspring and alters the resting membrane potential of NAc MSNs. A, A 10-min, 10-Hz local field stimulation of the NAc of the adult offspring of sham-treated dams (N = 10) elicited a robust eCB-LTD. However, this same protocol failed to induce eCB-LTD in the adult offspring of dams treat with WIN (N = 12). B, fEPSP magnitude at baseline (−10−0 min) and LTD (35–40 min post-tetanus) values corresponding to the normalized values in A (two-way RM ANOVA, F_(1,20) = 20.49, p = 0.0002; Sidak’s multiple comparisons test, p = 0.0002 and p = 0.3087 for sham and WIN, respectively). C, Current injection steps of 50 pA from –400 to 150 pA revealed no differences in the I-V relationship in MSNs of the NAc between the adult offspring of sham-treated and WIN-treated dams (N = 14, 14, respectively). D, Action potentials elicited by progressive current injections from 0 to 600 pA revealed no difference in the number of spikes elicited in pyramidal neurons of the PFC in slices obtained from the adult offspring of WIN-injected dams as compared with those from sham-treated dams (N = 14, 14, respectively; two-way RM ANOVA, F_(20,250) = 0.6092, p = 0.9071). E, Progressive current injections in 10-pA steps from 0 to 200 pA revealed that the minimum current injection required to elicit an action potential (i.e., rheobase) did not differ in MSNs of NAc slices obtained from the adult offspring of WIN-treated, as compared with sham-treated, dams (N = 14, 14, respectively; two-tailed t test, p = 0.9502). F, However, MSNs in NAc slices obtained from the adult offspring of WIN-treated dams exhibited significantly lower resting membrane potentials than those obtained from sham-exposed offspring (N = 14, 14, respectively; two-tailed t test, p = 0.0003); *p < 0.05.