**5. Conclusions**

Chronic CBD treatment did not prevent PTZ-induced kindling in rats, but a reduction in mortality associated with prolonged status epilepticus was observed. Analyzing the seizure activities, it was found that the frequency and duration were not influenced by CBD, but the latency to the first generalized seizure was increased. The NOR test showed that CBD treatment impaired recognition memory, which may warrant further investigation. The main findings of the study (i.e., reduced mortality and cognitive dysfunction) may be connected to the observed hippocampal histological changes, such as reduced thickness of the stratum pyramidale or decreased astrogliosis.

**Supplementary Materials:** The following supporting information can be downloaded at: https:// www.mdpi.com/article/10.3390/biomedicines10081811/s1, Figure S1: The potential fragmentation of CBD in negative electrospray ionization and the characteristic MRM mass spectrum of CBD (313 *m*/*z* → 245 *<sup>m</sup>*/*<sup>z</sup>*, collision energy: 20 eV); Figure S2: The chromatograms obtained for the quantification limits (A: plasma with 1 ng/mL CBD and B: homogenized brain sample with 1 ng/ml CBD) and the representative chromatograms of the real samples (C: plasma with 47.3 ng/ml CBD and D: homogenized brain sample with 6.0 ng/ml CBD); Figure S3: Schematic illustration of the novel object recognition task; Figure S4: Bland–Altman plots representing the agreemen<sup>t</sup> between the

cell counter algorithm and human manual counting of NeuN, GFAP, and IBA1 positive cells in the rat hippocampus; Figure S5: Representative image of morphological changes in the CA3 hippocampal pyramidal layer of (a) PTZ kindled controls and (b) CBD treated rats; Table S1: The chromatographic conditions and the MS detector parameters used for the analysis of plasma and homogenized brain tissue samples; Table S2: The summary of the analytical method validation process.

**Author Contributions:** Conceptualization, Z.G. and K.K.; formal analysis, S.V. and M.K.; funding acquisition, Z.G.; investigation, Z.G., K.K., A.T., R.B. and M.U.; methodology, K.K., A.T., E.F. and S.V.; project administration, Z.G.; software, Z.G., K.K., A.T., I.Z., I.S. and R.B.; supervision, S.V. and M.K.; validation, S.V. and M.K.; visualization, Z.G., K.K. and R.B.; writing—original draft, Z.G., K.K., E.F. and M.U.; writing—review and editing, R.B. and M.K. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the University of Medicine, Pharmacy, Science and Technology "George Emil Palade" of Târgu Mures, Research gran<sup>t</sup> number 293/3/14.01.2020.

**Institutional Review Board Statement:** The animal study protocol was approved by the Ethics Committee of George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures (63/2018).

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Acknowledgments:** The authors thank Trigal Pharma GmbH (Wien, Austria) for donating the crystalline cannabidiol used in this study.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
