h-89 and Memory-Disorders

Topics: Animals; Cyclic AMP; Cyclic AMP Response Element-Binding Protein; Cyclic AMP-Dependent Protein Kinases; Estrogens; Female; Iron; Isoquinolines; Male; Memory Disorders; Ovariectomy; Rats; Receptors, Estrogen; Signal Transduction; Sulfonamides

Our aim was to investigate the effects of resveratrol, auraptene, and curcumin on the spatial learning and spatial memory retention in the Morris water maze (MWM). The effects of 4-day bilateral intrahippocampal (i.h.) infusions of dimethyl sulfoxide (DMSO), H-89 as a protein kinase AII inhibitor, auraptene/H-89, resveratrol/H-89, and curcumin/H-89 were investigated on spatial memory acquisition in MWM. The rats were trained for 4 days; each day included one block of four trials. Post-training probe tests were performed on day 5 in acquisition test. For retention assessments, different animals were trained for 4 days and then infused (i.h.) with either DMSO, H-89, auraptene/H-89, resveratrol/H-89, or curcumin/H-89. The retention test was performed 48 h after the last training trial. The bilateral infusion of H-89 led to a significant impairment in spatial memory in acquisition and retention tests accompanied with a significant decrease in expressions of cAMP response-element binding (CREB) and pCREB proteins in hippocampus. Resveratrol and curcumin reversed the H-89-induced spatial memory acquisition and retention impairments with significant increases in both CREB and pCREB proteins expressions compared to H-89-treated animals. Auraptene showed significant effects in reversing H-89-induced impairments in spatial memory retention but not spatial memory acquisition.

Topics: Animals; Coumarins; Curcumin; Cyclic AMP Response Element-Binding Protein; Hippocampus; Infusions, Parenteral; Isoquinolines; Male; Memory; Memory Disorders; Neuroprotective Agents; Rats, Wistar; Resveratrol; Sulfonamides

Oxidative stress and mitochondrial dysfunction play indispensable role in memory and learning impairment. Growing evidences have shed light on anti-oxidative role for melatonin in memory deficit. We have previously reported that inhibition of protein kinase A by H-89 can induce memory impairment. Here, we investigated the effect of melatonin on H-89 induced spatial memory deficit and pursued their interactive consequences on oxidative stress and mitochondrial function in Morris Water Maze model. Rats received melatonin (50 and 100μg/kg/side) and H-89(10μM) intra-hippocampally 30min before each day of training. Animals were trained for 4 consecutive days, each containing one block from four trials. Oxidative stress indices, including thiobarbituric acid (TBARS), reactive oxygen species (ROS), thiol groups, and ferric reducing antioxidant power (FRAP) were assessed using spectrophotometer. Mitochondrial function was evaluated through measuring ROS production, mitochondrial membrane potential (MMP), swelling, outer membrane damage, and cytochrome c release. As expected from our previous report, H-89 remarkably impaired memory by increasing the escape latency and traveled distance. Intriguingly, H-89 significantly augmented TBARS and ROS levels, caused mitochondrial ROS production, swelling, outer membrane damage, and cytochrome c release. Moreover, H-89 lowered thiol, FRAP, and MMP values. Intriguingly, melatonin pre-treatment not only effectively hampered H-89-mediated spatial memory deficit at both doses, but also reversed the H-89 effects on mitochondrial and biochemical indices upon higher dose. Collectively, these findings highlight a protective role for melatonin against H-89-induced memory impairment and indicate that melatonin may play a therapeutic role in the treatment of oxidative- related neurodegenerative disorders.

Topics: Animals; Antioxidants; Cytochromes c; Disease Models, Animal; Escape Reaction; Hippocampus; Hypnotics and Sedatives; Isoquinolines; Lipid Peroxidation; Male; Melatonin; Membrane Potential, Mitochondrial; Memory Disorders; Mitochondria; Protein Kinase Inhibitors; Rats; Rats, Wistar; Reaction Time; Reactive Oxygen Species; Sulfonamides; Xylazine

In spite of characterizing the role of protein kinase A (PKA) in activating biochemical mechanisms, few studies have investigated the effects of PKA inhibitors on memory functions. In the present study, we used Pavlovian fear conditioning paradigm to evaluate memory alterations caused by two doses of H89 (as a conditional inhibitor of PKA) alone and in combination with amyloid-β (Aβ) in rats. Moreover, we used the Western blotting method to investigate the alterations in markers of transcription, oxidative stress, inflammation, and apoptosis pathways involved in memory impairment. Stereotaxic surgery was done to inject Aβ (30 ng/side) directly into the hippocampal CA1 area bilaterally and H89 (5 or 10 μM) intracerebroventricular unilaterally. One series of rats were trained 7 days after injections, then contextual and tone tests were conducted on days 8 and 9, respectively. Second series of rats were trained 14 days after the injections and tests were carried out on days 15 and 16. Our behavioral results showed that H89 (5 μM) not only has no destructive effect on memory, but also attenuates memory deficit caused by Aβ in combination groups. In contrast, H89 (10μM) has a reversible destructive effect on memory. Our molecular findings indicated that low dose of H89 increases CREB phosphorylation, Nrf2 and HO-1 which results in survival resistance to the stress. On the contrary, H89 with higher concentration leads to substantial increase of NF-κB and caspase-3 levels, which impair memory functions. In conclusion, our data suggest that H89 as a PKA inhibitor influences memory process through a dose and time dependent manner.

Topics: Amyloid beta-Peptides; Animals; Caspase 3; Conditioning, Classical; CREB-Binding Protein; Cyclic AMP-Dependent Protein Kinases; Disease Models, Animal; Dose-Response Relationship, Drug; Fear; Freezing Reaction, Cataleptic; Heme Oxygenase-1; Isoquinolines; Male; Memory Disorders; NF-E2-Related Factor 2; Rats; Rats, Wistar; Sulfonamides; Time Factors

Alzheimer's disease (AD), the most relevant cause of dementia in elderly, is characterized by amyloid β (Aβ) containing plaques and neurofibrillatory tangles, synaptic and neuronal loss, along with progressive cognitive impairment in short-term memory. However, mechanistic links between protein kinase A (PKA), oxidative stress and memory loss in response to Aβ remain elusive. In the present study, we examined the effects of post-training bilateral intra-hippocampal infusions of the specific protein kinase AII inhibitor, H-89, on memory deficits induced by Aβ (1-42) in Aβ-pretreated rats. H-89 and Aβ were administered immediately after completion of training. All animals were trained for 4 consecutive days and tested 9 and 19 days after the infusions. Significant differences were observed in the time and distance of finding the hidden platform in Aβ treated animals after 19 days. Interestingly, intra-hippocampal infusion of H-89 (5μM/side) significantly prevented the Aβ-induced memory impairment. Furthermore, evaluation of NFκB (nuclear factor-κB), and antioxidant enzymes, such as γ-GCS (glutamylcysteine synthetase), HO-1 (hemeoxygenase-1), GSH (glutathione), and SOD (superoxide dismutase) confirmed the protective effect of H-89. Given the possible neuroprotective effects of H-89 on Aβ-induced memory impairment, our results may open a new avenue for the prevention of AD by PKAII signaling pathway inhibitor.

Topics: Amyloid beta-Peptides; Animals; Cyclic AMP-Dependent Protein Kinases; Glutathione; Hippocampus; Isoquinolines; Male; Maze Learning; Memory Disorders; Memory, Short-Term; NF-kappa B; Oxidative Stress; Peptide Fragments; Protein Kinase Inhibitors; Rats; Rats, Wistar; Sulfonamides

The role of protein kinase AII (PKA II) in spatial memory retention in male rats and its regulation of cholinergic gene expression were explored through the effects of intrahippocampal infusion of H-89, a selective PKA II inhibitor. Alterations in escape latency, travel distance, and swimming speed in a Morris water maze were measured. Animals were trained for 3 days; each day included two blocks, and each block contained four trials. Stereotaxic surgery was employed for the infusions after the last trial on the third day of training, and the animals were tested 48 hr after surgery. Bilateral intrahippocampal infusion of H-89 (2.5 or 5 microM) into the CA1 region generated significant alterations in escape latency and traveled distance but not swimming speed. The response was fairly dose dependent, and the maximal effect was obtained with 5 microM H-89. After behavioral testing, several of the infused animals were transcardially perfused and their brains removed. Brain tissue sections from these rats were subjected to immunohistochemical staining analysis with anticholine acetyltransferase (ChAT) antibodies. These analyses indicated that 5 microM H-89 infusions qualitatively reduced the density of ChAT-containing cholinergic nerve terminals in the dorsal hippocampus. The intrahippocampal infusions with 5 microM H-89 also caused an apparent reduction in the number of ChAT-containing neurons in the medial septum. Our results suggest that PKA II is involved in regulation of cholinergic gene expression and plays an important role in spatial memory retention in rats.

Topics: Acetylcholine; Animals; Choline O-Acetyltransferase; Cholinergic Fibers; Cyclic AMP-Dependent Protein Kinases; Dose-Response Relationship, Drug; Down-Regulation; Enzyme Inhibitors; Gene Expression Regulation; Hippocampus; Immunohistochemistry; Isoquinolines; Male; Maze Learning; Memory; Memory Disorders; Rats; Rats, Wistar; Space Perception; Sulfonamides