MPTP hydrochloride

Note:
Please do not refer to only one article to determine the experimental conditions. It is recommended to determine the optimal experimental conditions (animal strain, age, dosage, frequency and cycle, detection time and indicators, etc.) through preliminary experiments before the formal experiment.

MPTP hydrochloride can be used in animal modeling to create Parkinson's disease models. MPTP replicates naturally occurring neurodegeneration and is useful for studying dopaminergic neuronal degeneration, mitochondrial dysfunction, and neuroinflammation. After injection, MPTP is rapidly metabolized to MPP+, which has a serum half-life of approximately 6 days in sheep.

Frequently Asked Question (FAQ):
1. Which mouse strain should be used and how old are they?
Currently, male C57bl/6 mice are commonly used in the references. Mice should be at least 8 weeks old, and 8-12 weeks mice are commonly used. The optimal weight is 25-30 g. Experimental reproducibility is better in mice above 8 weeks of age, and older mice may be more sensitive; In the acute model validated by MCE, 12 weeks of age - 23.4 mg/kg had a better modeling effect than 12 weeks of age - 20 mg/kg, and than 7 weeks of age-25 mg/kg (TH IHC staining)
2. Which administration route should be used?
Although MPTP can be administered by a variety of different routes, including oral gavage and stereotaxic injection into the brain, the most common, and reproducible, results are obtained by systemic subcutaneous (s.c.) or intraperitoneal (i.p.) injection.
3. How should I choose the dosage?
The commonly used protocols in the references are acute model (20 mg/kg, i.p., given every 2 hours within a day, a total of 4 times) and subacute model (30 mg/kg, i.p., once daily for 5 days).
4. What phenotypes in mice can I observe?
Generally speaking, We can observe whether the mice have symptoms such as reduced activity, staggering walking, twitching, fried hair, increased urination, etc. On acute dosing, this behavior may last for 24-48 hours, after which the mice behave basically normally. If the sub-acute dosing schedule is used, with the exception of piloerection, which is seen after the first dose, mice appear normal.
5. What markers can be detected to indicate the success of modeling?
1) Nigrostriatal injury: Tyrosine hydroxylase in the substantia nigra and striatum is reduced after successful modeling (IHC, IF, WB, etc.);
2) Other markers: reduction of brain neurotransmitters (DA, DOPAC, 5-HT, HVA, etc.) (detected by HPLC);
3) Nigrostriatal microglia (IBA1+ cells) and astrocytes (GFAP+ cells) are activated, and the number of α-syn aggregates in the substantia nigra increases; It has been reported that in the subacute model, 5 days after the last MPTP administration, the number of tyrosine hydroxylase (TH)-positive cells in the substantia nigra pars compacta decreased and the TH content in the striatum decreased, but TH-positive cells in the substantia nigra pars compacta began to recover 21 days after injection. In the acute model, the TH content gradually decreased after administration, and the loss of TH in the substantia nigra pars compacta was stable after 7 days.

Note:
1. MPTP is usually sold as MPTP hydrochloride. The molecular weight of MPTP hydrochloride is 209.7. Therefore, it is recommended to take into account the presence of hydrochloride (HCl) when preparing injectable solutions. HCl has a molecular weight of 35.4 and accounts for 17% of MPTP.
Thus, if a 20 mg/kg dose of MPTP is to be prepared, the MPTP hydrochloride dose administered is 20 mg kg* 1.17% = 23.4 mg/kg.
2. If multiple injections are given within 1 day, it is best to alternate the injections on both sides. If injected every day, it should be done at the same time. Before each injection, the mice need to be weighed and the dosage volume should be adjusted.
3. Modeling mice may not show behavioral defects of Parkinson's disease. Mice may show individual differences, and the success rate of modeling is generally difficult to reach 100%. Therefore nigrostriatal damage associated with gliosis should be mainly monitored in MPTP mouse studies.
4. High drug dosage/mice weighing less than 22 g/mixing of drugs from different batches/mice not adapting in advance/animal room being too cold may result in a number of deaths, and it is recommended that the number of animals in each group be increased.
5. It has been reported that in the subacute model, 5 days after the last MPTP administration, the number of tyrosine hydroxylase (TH)-positive cells in the substantia nigra pars compacta decreased and the TH content in the striatum decreased, but TH-positive cells in the substantia nigra pars compacta began to recover 21 days after injection. In the acute model, the TH content gradually decreased after administration, and the loss of TH in the substantia nigra pars compacta was stable after 7 days^[5][9].