Neuropeptides in the posterodorsal medial amygdala modulate central cardiovascular reflex responses in awake male rats

The rat posterodorsal medial amygdala (MePD) links emotionally charged sensory stimuli to social behavior, and is part of the supramedullary control of the cardiovascular system. We studied the effects of microinjections of neuroactive peptides markedly found in the MePD, namely oxytocin (OT, 10 ng and 25 pg; n=6/group), somatostatin (SST, 1 and 0.05 μM; n=8 and 5, respectively), and angiotensin II (Ang II, 50 pmol and 50 fmol; n=7/group), on basal cardiovascular activity and on baroreflex- and chemoreflex-mediated responses in awake adult male rats. Power spectral and symbolic analyses were applied to pulse interval and systolic arterial pressure series to identify centrally mediated sympathetic/parasympathetic components in the heart rate variability (HRV) and arterial pressure variability (APV). No microinjected substance affected basal parameters. On the other hand, compared with the control data (saline, 0.3 µL; n=7), OT (10 ng) decreased mean AP (MAP50) after baroreflex stimulation and increased both the mean AP response after chemoreflex activation and the high-frequency component of the HRV. OT (25 pg) increased overall HRV but did not affect any parameter of the symbolic analysis. SST (1 μM) decreased MAP50, and SST (0.05 μM) enhanced the sympathovagal cardiac index. Both doses of SST increased HRV and its low-frequency component. Ang II (50 pmol) increased HRV and reduced the two unlike variations pattern of the symbolic analysis (P<0.05 in all cases). These results demonstrate neuropeptidergic actions in the MePD for both the increase in the range of the cardiovascular reflex responses and the involvement of the central sympathetic and parasympathetic systems on HRV and APV.

Effect and mechanism of intermedin in acute rat cardiac ischemic injury / 法医学杂志

OBJECTIVE@#To investigate the effect and potential mechanism of intermedin (IMD) in acute cardiac ischemic injury and to provide a new approach for exploring mechanism of sudden cardiac death.@*METHODS@#Seventy-two healthy male rats were randomly divided into 3 groups: control, ischemic and the IMD-treated group. The activity of lactate dehydrogenase (LDH), malondialdehyde (MDA) and superoxide dismutase (SOD) in heart blood were tested by enzyme chemistry method. The mRNA changes of calcitonin receptor-like receptor (CRLR) and receptor activity-modifying proteins (RAMPs) in cardiac were measured by real-time PCR analysis. Myocardial cyclic adenosine monophosphate (cAMP) content was determined by enzyme linked immunosorbent assay (ELISA). Apoptosis related factors Bcl-2 and Bax were detected by immunohistochemistry.@*RESULTS@#Comparing with the control group, LDH and MDA activity of ischemic group in heart blood increased and SOD activity decreased. The concentration of cAMP increased in ventricular muscle, Bcl-2 and Bax proteins expression ratio level decreased. The intravenation of IMD decreased the level of increased activity of LDH and MDA, and lessened the level of decreased activity of SOD. The mRNA expression of CRLR and RAMPs obviously increased in ventricular muscle.@*CONCLUSION@#The protective effect of IMD against myocardial ischemic injury could be caused by decreasing the oxidative stress of ischemia and inhibiting the myocardial apoptosis.

Avances en la genética molecular de la obesidad / Advances in the molecular genetics of the obesity

In the last decade, specially after the discovery of leptin, several neuropeptides that regulate energy intake and expenditure have been described in animal models. This has partially unvelied the underlying mechanisms that regulate body composition and weight and therefore a promise of a more effective treatment of obesity and its comorbidities is ad portas

Secretion from neuropeptide-treated splenocytes modifies ovarian steroidogenesis

There are evidences for modulation of immune function by the sympathetic nervous system and its principal neurotransmitter norepinephrine (NE) throgugh superior ovarian nerve (SON)-coeliac ganglionnoradrenergic postganglionic innervation of the spleen. Seven days after SON transection at 53 days of age, the rat splenocytes were isolated and then cultured for 48h. These culture media, used to simulate ovaries from 60-day- old intact rats (neither SON-transected nor sham-operated) at diestrus 2 stage, in in vitro incubations, showed adecrease in progesterone release, an increase in estradiol release and no change in androstenedione release in relation to splenocyte culture media from control (sham-operated) rats.When esplenocytes from SON transected (SON-t) rats were treated with vasoactive intestinal peptide (VIP) or neuropeptide Y (NPY), both at 16-6M for 24h, their secretions increased the progesterone release while decreasing the estradiol release from the intact ovaries, compared with the secretions of untreated splenocytes from SON-t rats. Although the secretions of splenocytes treated with VIP decrease the androstenedione release from de ovaries, the treatment with NPY produced no change in hormone release. In the present paper the ovarian steroidogenic response, which was modified by the effects of an in vivo SON transection on spleen cells, was reverted by an in vitro system in which the splenocytes were treated with VIP or NPY. This could indicate that the spleen of SON-t rats does not receive those neuropeptides by neural route however, when they are added to splenocyte culture in vitro, the cell secretions revert the profile of steroid hormones released from the intact ovary. We also present functional evidence for modulation of the immune function by sympathetic nervous system and neurotransmitters other than NE.

PTTH--a potential growth activator in silkworm, Bombyx mori L. for enhancing silk production.

In silkworm, prothoracicotropic hormone (PTTH), directly or indirectly controls silk production and spinning activity along with juvenile hormone (JH). An effort was made to exploit the potential of PTTH by indirectly activating silk gland for increasing silk productivity using short chain synthetic analogues of PTTH. The analogy in action was also established using PTTH extracted from the silkmoth. Different doses of 42 synthetic PTTH analogues, viz., 2.5, 5, 10 and 20ppm and 3.3 mg/ml of PTTH extracted from silkmoth heads were administered orally to V instar silkworm larvae (Race:KAxNB4D2 and PMxNB4D2) at 0-144 hr at an interval of 24 hr. The analysed data showed an improvement of about 14 - 23% in KA x NB4D2 and about 10-14% in PMxNB4D2 in respect of cocoon shell weight on administration of some of the synthetic PTTH analogues. The PTTH extracted from the adult brain also showed similar effect. The structural analogy of synthetic PTTHs (which improved the shell weight) with original PTTH and its probable mode of action in silkworm are discussed.

role of non adrenergic non-cholinergic system in the peristaltic reflex of guinea pig ileum

The effect of some endogenous components -endogenous opiates, cholecystokinin [CCK], vasoactive intestinal polypeptide [VIP] and somatostatin-as inhibitory or excitatory transmitters in the local nervous pathways involved in peristaltic responses was examined. The peristaltic reflex was studied using a modification of the Trendelenberg preparation. In each preparation, the luminal distension pressure was increased in sudden steps of 1 cm H2O at intervals of 10, until peristalsis was initiated. Morphine inhibited the rhythmic peristaltic activity. The inhibitory effect of morphine was characterized by a decreased activity of both the longitudinal and circular muscle layers. Addition of naloxone to the organ bath reversed this inhibitory effect of morphine. Using distension pressures which evoke only tetrodotoxin-sensitive peristaltic contractions, the mechanism rapidly ' 'fatigues". This fatigue can be reversed by naloxone. Higher distending pressure, which can evoke tetrodotoxin-resistant activity, produced persistent peristalsis with intermittent activity seize. Addition of naloxone reversed the blockade leading to a continuous uninterrupted peristalsis. Proglumide or dbcGMP [selective inhibitor of the effects of CCK] increased the threshold pressure necessary to cause the peristaltic reflex and blocked all responses to threshold distension,Cholecystokinin or caerulein decreased the threshold of distension pressure required to evoke the peristaltic reflex. Furthermore, it increased the height and duration of the responses. The excitatory effect of CCK or caerulein was blocked by proglumide or dbcGMP. VIP increased the threshold of distension required to cause the peristaltic reflex and blocked the responses to threshold distension of longitudinal but not circular muscle layers. Somatostatin has been proved to exert an unusual effect on peristalsis. At high concentration it decreased the duration of the responses but had no effect on the height of rhythmic activity. It is concluded that the activation of intramural neurones by distension causes the release of inhibitory and excitatory transmitters, such as endogenous opiates which interrupts peristaltic activity and CCK which enhance the peristaltic reflex at a synapse with cholinergic neurones since CCK releases acetylcholine from intrinsic nerves. VIP and somatostatin are involved in the peristaltic reflex but the mechanism of their actions are not studied in this work