ARTICLE CRITIQUE

\Article Critique

Article Critique

Introduction

Various studies prove that acute immobilization stress results in increased mRNA expression of a neurohormone Arginine vasopressin (AVP), present in the paraventricular nucleus of the hypothalamus, the parvocellular neurons (PVNpc), as well as, increased ACTH and corticosterone levels in the plasma. On the other hand, new studies reveals newly formed mRNA transcripts for both CRH and AVP in the PVN, are expressed in the cytoplasm many hours after the onset of stress. Repeated immobilization produces even greater concentration of plasma corticosterone and AVP mRNA expression (Berger, 2006).

The study of Zhou, Leri, Cummins, Hoeschele, and Kreek, in 2008 aims to focus on (1) mRNA levels of AVP in Amygdala or hypothalamus, in addition to, the activity of hypothalamic-pituitary-adrenal (HPA), alterations during administration of chronic intermittently increasing heroin (10 days; 6.7 to 60 mg/kg/day)or the spontaneous withdrawal in the early (12hr) and late (10 days) phases; (2) hot foot shock stress alters the level of mRNA AVP in the Amygdala or hypothalamus of self-administered withdrawal in rats (infusion of 0.05mg/kg, 3h/day for 7 days); and, (3) if the antagonists SSR149415 of selective V1b receptor (1 and 30mg/kg, intraperitoneal)changes the seeking of heroin during the reinstatement tests stimulated via foot shock stress plus primes of heroin (0.25mg/kg), in addition to, the responses of HPA hormones to soot shock (Zhou, Leri, Cummins, Hoeschele, & Kreek, 2008, pp. 226-236).

Discussion

Background

Arginine vasopressin (AVP) is an important nonapeptide, expressed in numerous areas of the brain. Its primary function is in osmoregulation; however, it also plays a role in regulating the behaviour of patterns, the normal circadian rhythms, aggression, and in response to stress. The gonadal steroid hormones regulate the AVP gene expression occurring at bed nucleus of stria terminalis (BST). Although, the regulation of gonadal steroid hormones expressing at medial Amygdala (MeA) along with suprachiasmatic nucleus (SCN) are unclear (Pak, Chung, Hinds, & Handa, 2009, pp. 1409-1413).

Stress is a well-recognized factor for contributing to drug addiction. The drug cravings are elevated by psychological stress, and the stress-induced hypothalamic-pituitary-adrenal (HPA) responses, which predict the amount of following drug use. Withdrawal from the drugs itself acts as a major stressor promoting the compulsive drug abuse. Literature is available proving the vasopressinergic neuronal activity present in the hypothalamus and Amygdala, representing significant stress-related behaviour with respect to neuroscience. In rat models, AVP levels extracellular in the Amygdala and hypothalamus increases and activation of AVP V1b receptors modulating behaviours, which are anxiogenic and depressive (Zhou, et al., 2008, p. 226-236).

The Study

During 1980s, studies demonstrated that desglycinamide-(Arg8) vasopressin reduces self-administration of drugs, like heroin and cocaine. Moreover, the administration of AVP intracerebroventricularly increases self-administration of cocaine. The study focuses on the AVP gene expression alteration in chronic exposure of heroin, as well as, its spontaneous withdrawal. The authors used a regimen for administration to heroin-dependent individuals in a chronic intermittent increasing dose of heroin, mimicking the doses individuals take previously. The effects of the regimen were monitored in chronic (10 days), early (12 ...