The effect of paragigantocellularis lateralis lesion on conditioned place preference (CPP) in presence or absence of α2 adrenergic agonist (clonidine) in male rats

The nucleus paragigantocellularis lateralis (LPGi) is located in the rostral ventrolateral medulla (RVLM), a brain stem region that regulates homeostatic functions such as blood pressure and cardiovascular reflexes, respiration, pain and opiate withdrawal syndrome. LPGi has many anatomical relationships with important nuclei such as arcute nucleus, caudal raphe nucleus, periaqueductal gray (PAG), locus coeruleus (LC), and dentate. In this study we have examined the role of LPGi in the conditioned place preference (CPP) induced by morphine in the presence and absence of clonidine in the rat. We used 49 male N-MRI rats which were divided into 7 groups randomly: 1: Control, 2: Control+saline, 3: sham control, 4: lesion, 5: lesion +0.02 mg/kg clonidine, 6: lesion +0.2 mg/kg clonidine, 7: lesion +2 mg/kg clonidine. Animals were anaesthetized with ketamine (110 mg/kg) and rampune (Xylazine) (3 mg/kg) mixture. In the process of surgery LPGi nucleus has been destroyed bilaterally by DC electrical current (1 mA, 6 second), with stainless steel electrode placed in stereotaxic coordinates of (AP=11.8, Lat±1.86 and Depth=10.5). After the recovery period, they were treated with clonidine one hour before the application of Hand's method to induce CPP. We have not found any significant differences between the results of control, control+saline and sham groups in the CPP test but there is a significant increase in the CPP time between sham and LPGi lesion+saline groups (P<0.019). Clonidine at different doses (0.02, 0.2 and 2 mg/kg) have decreased CPP time in LPGi lesioned group in comparison with lesioned+saline group as well (p<0.002). In this study we have also demonstrated that clonidine has not any effects on the CPP time in the intact animals. Our results indicate that LPGi lesion induces CPP. It seems that LPGi is involved in drug reinforcements and also LPGi lesion induces sensitivity to α2 adrenergic agonist

Evaluation of immunocastration conjugates based on GnRH linked to carrier molecules in a male rodent model

Gonadotropin-releasing hormone (GnRH) stimulates the pituitary gland to secrete sex hormones. In the present study, we evaluated different conjugates of GnRH to abrogate sex hormone secretion in a male rat model. Firstly, GnRH-I was conjugated to keyhole limpet haemocyanin (KLH) using either whole-sequence GnRH-I or an analogue of GnRH-I (CHWSYGLRPG-NH2) using glutaraldehyde cross linkage. Six-week-old Sprague-Dawley male rats (n=6) were immunized intramuscularly with the conjugates adsorbed onto alum, equivalent to 50 μg of GnRH peptide and administered in weeks 1, 3, 5 and 7. The study was concluded in week 15. Comparison was made with untreated controls and previously established anti-fertility conjugates: CHWSYGLRPG-NH2 (GnRH-I) or CHWSHDWKPG-NH2 (analogue of lamprey GnRH-III, lGnRH-III) linked to tetanus toxoid (using a heterobifunctional reagent to achieve cross linkage). Antibody production, hormone levels and testicular diameter changes were assessed, together with, sperm movement and effects on organ weights. Similar high levels of antibody secretion were observed in all the immunized groups, although whole GnRHI- KLH produced a sustained level of production for an additional week. Similarly, testosterone levels were significantly (p<0.05) reduced in all immunized groups. There were no significant changes observed in body weight and testicular diameter of immunized animals compared with the untreated controls. However, in terms of sperm motility and sperm number, the best anti-fertility effects were observed with lGnRH-III-TT and GnRH-I-KLH and to a lesser extent whole GnRH-I-KLH. These groups also showed significant increase in kidney weight. Finally, considering all the above-mentioned subjects in addition to availability and easier and cheaper way of preparation,we came to this conclusion that whole GnRH-IKLH satisfactorily met most of our favourite criteria and could be used in immunocastration vaccine production purposes successfully