Differential action of methamphetamine on tyrosine hydroxylase and dopamine transport in the nigrostriatal pathway of μ-opioid receptor knockout mice.

Extensive anatomical and functional interactions exist between central dopaminergic and opioidergic systems and both systems are proposed to be targets for amphetamine-like drugs. We have previously reported that μ-opioid receptor (μ-OR) knockout mice are resistant to the loss of dopamine in the striatum and the development of behavioral sensitization induced by repeated methamphetamine (METH) treatment. The present study assessed whether METH-treated μ-OR knockout mice exhibit a differential response of the expression of dopamine transporter and tyrosine hydroxylase (TH), the rate-limiting enzyme for dopamine synthesis and maintaining dopamine levels.

Methamphetamine-induced changes in the striatal dopamine pathway in μ-opioid receptor knockout mice.

Background: Repeated exposure to methamphetamine (METH) can cause not only neurotoxicity but also addiction. Behavioral sensitization is widely used as an animal model for the study of drug addiction. We previously reported that the μ-opioid receptor knockout mice were resistant to METH-induced behavioral sensitization but the mechanism is unknown.

mu-Opioid receptor knockout mice are insensitive to methamphetamine-induced behavioral sensitization.

Repeated administration of psychostimulants to rodents can lead to behavioral sensitization. Previous studies, using nonspecific opioid receptor (OR) antagonists, revealed that ORs were involved in modulation of behavioral sensitization to methamphetamine (METH). However, the contribution of OR subtypes remains unclear.

[Histaminergic receptor in the NTS involved in inhibition of carotid baroreflex induced by intracerebroventricular injection of HA in rats].

Aim: To explore the role of histaminergic receptors in the nucleus tractus solitarius (NTS) in the responses of carotid baroreflex (CBR) performance to the intracerebroventricular (ICV) injection of histamine (HA).

Methods: The left and right carotid sinus regions were isolated from the systemic circulation in 18 Wistar rats anesthetized with pentobarbital sodium. The intracarotid sinus pressure (ISP) was altered in a stepwise manner.