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PubMed2003

Endomorphin-1 causes synovial hypoaemia in rat knee joints via a capsaicin-sensitive neural pathway.

In joints, synthetic mu-opioids reduce inflammatory changes such as protein extravasation and associated oedema formation. However, the effect of endogenous opioid peptides on other inflammatory processes such as altered tissue blood flow has not been investigated. The present study examined the peripheral effects of the endogenous mu-opioid ligand endomorphin-1 (EM-1) on rat knee joint blood flow using laser Doppler perfusion imaging. Topical application of EM-1 (10(-16)-10(-9) mol) to exposed rat knee joints resulted in a dose-dependent increase in synovial vascular resistance with a maximum rise of 56% occurring with the 10(-9) mol dose. Destruction of unmyelinated articular afferents by capsaicin treatment completely abolished the hypoaemic effects of EM-1. These findings suggest that EM-1 acts peripherally in knee joints to decrease synovial blood flow, and this hypoaemic response is dependent on the presence of capsaicin-sensitive nerves.

Analgesics, Opioid↗

PubMed2004

Differential expression of glutamate receptors in avian neural pathways for learned vocalization.

Learned vocalization, the substrate for human language, is a rare trait. It is found in three distantly related groups of birds-parrots, hummingbirds, and songbirds. These three groups contain cerebral vocal nuclei for learned vocalization not found in their more closely related vocal nonlearning relatives. Here, we cloned 21 receptor subunits/subtypes of all four glutamate receptor families (AMPA, kainate, NMDA, and metabotropic) and examined their expression in vocal nuclei of songbirds. We also examined expression of a subset of these receptors in vocal nuclei of hummingbirds and parrots, as well as in the brains of dove species as examples of close vocal nonlearning relatives. Among the 21 subunits/subtypes, 19 showed higher and/or lower prominent differential expression in songbird vocal nuclei relative to the surrounding brain subdivisions in which the vocal nuclei are located. This included relatively lower levels of all four AMPA subunits in lMAN, strikingly higher levels of the kainite subunit GluR5 in the robust nucleus of the arcopallium (RA), higher and lower levels respectively of the NMDA subunits NR2A and NR2B in most vocal nuclei and lower levels of the metabotropic group I subtypes (mGluR1 and -5) in most vocal nuclei and the group II subtype (mGluR2), showing a unique expression pattern of very low levels in RA and very high levels in HVC. The splice variants of AMPA subunits showed further differential expression in vocal nuclei. Some of the receptor subunits/subtypes also showed differential expression in hummingbird and parrot vocal nuclei. The magnitude of differential expression in vocal nuclei of all three vocal learners was unique compared with the smaller magnitude of differences found for nonvocal areas of vocal learners and vocal nonlearners. Our results suggest that evolution of vocal learning was accompanied by differential expression of a conserved gene family for synaptic transmission and plasticity in vocal nuclei. They also suggest that neural activity and signal transduction in vocal nuclei of vocal learners will be different relative to the surrounding brain areas.

Alternative Splicing↗

PubMed1994

Sexually dimorphic cell groups in the medial preoptic area that are essential for male sex behavior and the neural pathways needed for their effects.

The research summarized here shows that the two major cell groups of the sexually dimorphic area (SDA) of the gerbil hypothalamus are essential for male sex behavior. Bilateral cell-body lesions of either the medial or lateral SDA virtually eliminate mating in sexually experienced male gerbils given exogenous testosterone. Similar deficits occur when the SDA is bilaterally disconnected from the retrorubral field (RRF) as a result of unilateral cell-body lesions in the SDA and contralateral RRF. The A8 cells of the RRF do not account for this effect. Bilaterally disconnecting the SDA from the caudomedial part of the bed nucleus of the stria terminalis (caudal BSTm) also eliminates sexual activity. Disconnecting the SDA from the medial amygdala does not mimic this effect. Neither does disconnecting the medial amygdala from the caudal BSTm. Thus, caudal BSTm neurons that are essential for mating via connections with the SDA do not simply relay information from the medial amygdala.

Amygdala↗

PubMed1996

Involvement of NO-ergic neural pathway in reflex tracheal dilatation during bronchoconstriction in guinea pigs.

The involvement of NOergic nerve in vagal reflex-mediated tracheal dilatation during bronchoconstriction was investigated using the guinea pig in vivo tracheo-bronchi separated preparation. Inhalation of 0.01% histamine to the bronchial site induced a biphasic, vagal reflex tracheal response, i.e., constriction followed by dilatation slightly after bronchial constriction. The reflex tracheal dilatation was inhibited by 49% by local treatment of the tracheal site with 1% propranolol. The residual dilatation in the presence of atropine and propranolol was significantly inhibited by 1% oxyhemoglobin or 1% carboxy-PTIO, NO scavengers. Cyclic GMP content in the tissue of the tracheal site during the reflex tracheal dilatation significantly increased. The increase in cyclic GMP was reduced by treatment of the tracheal site with 1% N omega-nitro-L-arginine methyl ester. These results support a hypothesis that reflex tracheal dilatation during bronchoconstriction may be mediated by not only adrenergic but also NOergic nerves in guinea pigs.

Administration, Inhalation↗

PubMed2006

Separate neural pathways process different decision costs.

Behavioral ecologists and economists emphasize that potential costs, as well as rewards, influence decision making. Although neuroscientists assume that frontal areas are central to decision making, the evidence is contradictory and the critical region remains unclear. Here it is shown that frontal lobe contributions to cost-benefit decision making can be understood by positing the existence of two independent systems that make decisions about delay and effort costs. Anterior cingulate cortex lesions affected how much effort rats decided to invest for rewards. Orbitofrontal cortical lesions affected how long rats decided to wait for rewards. The pattern of disruption suggested the deficit could be related to impaired associative learning. Impairments of the two systems may underlie apathetic and impulsive choice patterns in neurological and psychiatric illnesses. Although the existence of two systems is not predicted by economic accounts of decision making, our results suggest that delay and effort may exert distinct influences on decision making.

Animals↗

PubMedDate not supplied

Molecular mechanisms and neural pathways mediating the influence of interleukin-1 on the activity of neuroendocrine CRF motoneurons in the rat.

The action of immune-system-derived cytokines to stimulate the release of corticotropin-releasing factor (CRF) from the hypothalamus and the consequent elaboration of ACTH and release of corticosteroids has provided an especially useful model to investigate the nature of the intercommunication of neuroendocrine and immunological pathways. Substantial evidence exists to support the production of cytokines, such as interleukin-1 (IL-1) alpha and beta, within the mammalian central nervous system. The mechanisms and neuronal circuitries involved in the effects of these cytokines of peripheral and central origin on the activity of neuroendocrine CRF motoneurons and the hypothalamic-pituitary-adrenal axis are described. Also included is a discussion of the influence of IL-1 on transduction signals controlling the release and the biosynthesis of CRF in the parvocellular division of the paraventricular nucleus of the hypothalamus and the relationship between these two distinct intracellular processes. The relevance of using immediate early genes as indices of neuronal activity in immune-challenged rats and the possible roles of c-fos and NGFI-B within neuroendocrine CRF motoneurons are outlined. Finally, the effects of acute immune response on neuroendocrine functions and brain neuronal activation are presented.

Animals↗

PubMed1986

Identification of the neural pathway for reinforcement of feeding when Aplysia learn that food is inedible.

Bilateral sectioning of the esophageal nerves that innervate the gut of Aplysia was found to have profound effect on response decrement to inedible food: Time to criterion for cessation of feeding was elevated, no memory of the decrement was present 24 hr after training, and motor patterning during training was altered. The parametric features of response decrement to sustained lip stimulation were examined to determine their resemblance to parameters of response decrement to inedible food after esophageal nerve sectioning. Parameters of response decrement were similar, indicating that after esophageal nerve sectioning response decrement is likely to be the result of sustained lip stimulation. Bilateral nerve sectioning had no effect on decrement due to sustained lip stimulation. Unilateral lesions and lesions of either of the two major divisions of the esophageal nerves had no effect on learning that food was inedible. The data indicate that bilateral nerve sectioning eliminates all stimuli causing negative reinforcement of feeding due to failure to consume food. Based on the data in this and the previous paper, a model is presented suggesting sites of action and mechanisms for learning that foods are edible or inedible in Aplysia.

Animals↗

PubMed1991

Splanchnic osmosensation and vasopressin: mechanisms and neural pathways.

Hypertonic (2 ml, 598 mosmol/kgH2O) solutions were infused over 4 min via a stomach tube in 12 groups (n = 5-10) of conscious rats with indwelling arterial catheters. Mean changes over 4-21 min of plasma arginine vasopressin (AVP) were 6.1 +/- 0.9 for NaCl (P less than 0.01), 9.3 +/- 3.0 for LiCl (P less than 0.01), 4.5 +/- 1.3 for sodium isethionate (P less than 0.01), 2.8 +/- 0.9 for sucrose (P less than 0.025), 3.9 +/- 2.8 for mannitol (P less than 0.01), and -0.1 +/- 0.1 (SE) pg/ml for urea. The AVP responses to NaCl and sucrose were proportional to the rate of gastrointestinal absorption of radiolabeled NaCl and sucrose, respectively. The AVP response to 598 mosmol/kgH2O NaCl was attenuated by 60.6% (P less than 0.001) in rats with lesion of the side branches of the major splanchnic nerves innervating the mesentery of the upper small intestine and the portal vein area, by 34-37% (P less than 0.05) in rats with right or left splanchnic nerve lesions, and was not affected by subdiaphragmatic vagotomy. Changes in systemic plasma osmolality were small and could not explain the AVP responses. Thus splanchnic receptors are osmosensitive, are situated in the mesentery of the upper small intestine and possibly the portal vein area, and project to the spinal cord via the right and left major splanchnic nerves.

Animals↗

PubMed2000

Inhibitory neural pathway regulating gastric emptying in rats.

The relaxation of the pylorus is one of the most important factors for promoting gastric emptying. However, the role of inhibitory neurotransmitters in the regulation of pyloric relaxation and gastric emptying remains unclear. In this study, we investigated the effects of NO biosynthesis inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME), and calcium dependent potassium channel blocker, apamin, on vagal stimulation-induced pyloric relaxation and gastric emptying in rats. Sodium nitroprusside (SNP), adenosine 5'-triphosphate (ATP), vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating peptide (PACAP) caused pyloric relaxations in a dose dependent manner in vivo. Apamin (120 microg/kg) significantly reduced ATP and PACAP-induced pyloric relaxations without affecting SNP- or VIP-induced relaxations. Vagal stimulation (10 V, 1 ms, 1-20 Hz)-induced pyloric relaxation was significantly inhibited by L-NAME (10 mg/kg). The combined administration of L-NAME and apamin almost completely abolished vagal stimulation-induced pyloric relaxation. L-NAME and apamin significantly increased spontaneous contractions in the antrum, pylorus and duodenum. Increased motility index by L-NAME and apamin was significantly higher in the pylorus and duodenum, compared to that of antrum. L-NAME and apamin significantly delayed liquid gastric emptying. These results suggest that besides NO, probably ATP and PACAP, act as inhibitory neurotransmitters in the rat pylorus and regulate gastric emptying.

Adenosine Triphosphate↗

PubMed1997

The circumventricular organs form a potential neural pathway for lactate sensitivity: implications for panic disorder.

Patients with panic disorder experience panic attacks after intravenous sodium lactate infusions by an as yet unexplained mechanism. Lactate elicits a panic-like response in rats with chronic dysfunction of GABA neurotransmission in the dorsomedial hypothalamus (DMH). The circumventricular organs, organum vasculosum lamina terminalis (OVLT) and subfornical organ (SFO), are potential sites that could detect increases in plasma lactate levels and activate the DMH. To test this, we obtained baseline heart rate (HR) and blood pressure (BP) responses to lactate infusions in rats fit with femoral arterial and venous catheters. Next, unilateral chronic injection cannulae connected to an Alzet infusion pump filled with the GABA synthesis inhibitor L-allylglycine (L-AG) were implanted into the DMH. Another chronic injection cannula was implanted into the region of the OVLT, SFO, or an adjacent control site, the median preoptic area (MePOA). These rats were tested once again with lactate infusions after injection of either artificial cerebrospinal fluid (ACSF) or tetrodotoxin (TTX) into the CVO sites. Injecting TTX into the OVLT completely blocked the lactate-induced response, whereas TTX injections into the SFO or MePOA did not. Also, direct injections of lactate (100 or 500 nl) into the OVLT elicited robust anxiety-like responses in these rats. These results suggest that the OVLT may be the primary site that detects lactate infusions, activating an anxiety-like response in a compromised DMH, and provide the first neuroanatomical basis for lactate response in panic disorder.

Allylglycine↗

PubMed2005

Altered Fos expression in neural pathways underlying cue-elicited drug seeking in the rat.

Cocaine treatment paired with environmental cues establishes a conditioned place preference for that environment. Following expression of this preference, rats show elevated levels of immediate early genes (e.g. c-fos) in the prelimbic cortex (PrL), basolateral amygdala complex (BLC) and nucleus accumbens core (NAcc) compared to drug-unpaired controls. The PrL and BLC are reciprocally connected and both project to the NAcc. Together with the immediate early gene findings, these connections suggest the regions interact as a circuit contributing to cue-elicited drug seeking. To study this circuit, we iontophoresed Fluorogold (FG) into one brain region and assessed colocalization of FG with place preference-induced Fos in the others. Following FG iontophoresis in either the PrL or NAcc, more BLC cells double-labelled for Fos and FG were found in drug-paired than unpaired animals. Following FG iontophoresis in either the BLC or NAcc, no differences were found in the absolute number of PrL Fos/FG cells. This pattern of colocalization suggests that exposure to cocaine-associated cues leads to greater activation of the BLC's efferents to both the PrL and NAcc, while PrL output to the NAcc and BLC is unaffected in IEG expression. These results complement recent findings that suggested attenuated PrL output during place preference expression. Our findings support the view that the BLC, rather than the PrL, provides significant excitatory driving to the NAcc during cue-elicited drug seeking.

Amygdala↗

PubMed1981

Neural pathways mediating basal and stress-induced secretion of luteinizing hormone, follicle-stimulating hormone, and testosterone in the rat.

Adult male rats, intact or bearing complete, anterior, or posterior hypothalamic deafferentations (CHD, AHD, or PHD, respectively) or bilateral medial forebrain bundle (MFB) lesions, were acutely exposed to visual, audiogenic, or thermal stress. Two to 30 min after stress onset, the rats were decapitated, and trunk blood was collected from serum LH, FSH, and testosterone (T) determinations. While basal serum LH levels were found to be normal in all experimental groups, FSH levels were reduced in CHD and AHD rats, and serum T concentrations were found to be 3-fold greater than control values in the AHD group. In intact animals, exposure to all modalities caused significant elevations in serum levels of both LH and T, with no effect on FSH secretion. In the CHD and AHD groups, the LH and T responses were eliminated, with the exception of the T response to heat exposure, which persisted in CHD animals. In the PHD group, the LH and T responses persisted and were, in fact, potentiated. Bilateral medial forebrain bundle lesions inhibited the LH and T responses to audiogenic and thermal, but not to visual, stimulation. These data demonstrate that 1) basal FHS, but not LH, secretion is dependent upon extrahypothalamic afferents to the medial basal hypothalamus; 2) acute neurogenic stress stimulates LH and T, but not FSH, secretion; and 3) central nervous system sites, rostral to the medial basal hypothalamus, mediate the stress-induced elevations in LH release.

Acoustic Stimulation↗

PubMed1999

Transneuronal tracing of neural pathways controlling activity of diaphragm motoneurons in the ferret.

Previous studies have shown that neurons in addition to those in the medullary respiratory groups are involved in activating phrenic motoneurons during a number of behaviors, including vomiting and reaction to vestibular stimulation. However, the location of premotor inspiratory neurons outside of the main medullary respiratory groups is largely unknown, particularly in emetic species. In the present study, the transneuronal tracer pseudorabies virus was injected into the diaphragm of the ferret, and the locations of retrogradely-labeled motoneurons and transneuronally-labeled pre-motoneurons in the brainstem and cervical and thoracic spinal cord were mapped. Injections of a monosynaptic tracer, cholera toxin, were also made in order to verify the location of motoneurons innervating the diaphragm. Phrenic motoneurons identified with pseudorabies virus and cholera toxin were confined largely to the C5-C7 levels of spinal cord, and often gave rise to prominent polarized dendritic arbors that extended across the midline. At post-inoculation survival times > or = three days, transneuronally-labeled interneurons were located in the cervical and thoracic spinal cord and portions of the brainstem, including the midline pontomedullary reticular formation and the lateral medullary reticular formation. Double-labeling studies revealed that although the infected midline neurons were located in the proximity of serotonergic neurons, only a small number of the virus-containing cells were positive for serotonin. These findings suggest that neurons in the midline of the medulla and pons influence the activity of phrenic motoneurons, perhaps during inspiratory behaviors unique to emetic animals (such as vomiting).

Animals↗

PubMed2000

Neural pathways for bilateral vocal control in songbirds.

Ipsilateral and contralateral projections of nucleus robustus archistriatalis (RA), a telencephalic vocal premotor nucleus, to respiratory-vocal nuclei in the brainstem were defined in adult male Wasserschlager canaries, grey catbirds, and zebra finches, three songbird species that appear to differ in the degree of lateralized syringeal dominance. In all three species, ipsilateral projections of RA to the medulla included the tracheosyringeal part of the hypoglossal nucleus (XIIts), that innervates the syrinx, the bird's vocal organ, the suprahypoglossal area (SH), and two respiratory-related nuclei, retroambigualis (RAm) and parambigualis (PAm; Reinke and Wild [1998] J Comp Neurol 391:147-163). Projections of RA to the contralateral XIIts, SH and RAm, were substantial in canaries, which use the left side of the syrinx predominantly during singing; less pronounced in catbirds, which have no lateral dominance for song control; and least pronounced in zebra finches, in which there is a right-sided dominance for song control. There were no obvious differences in the number of crossed projections in birds injected in the left or right RA. Local sources of inputs to XIIts and RAm were defined anatomically in zebra finches and canaries. RAm, including neurons in close proximity to XIIts, was found to project to XIIts and the suprahypoglossal area bilaterally but predominantly ipsilaterally. RAm also had reciprocal connections with its contralateral homologue. These results suggest a pattern of connections between premotor and motor respiratory-vocal nuclei that may be involved in bilateral control of vocal output at medullary levels, a control that involves a high degree of coordination between vocal and respiratory structures on both sides of the body.

Animals↗

PubMed1998

Volume expansion fails to normally activate neural pathways in the brain of conscious rabbits with heart failure.

Immunohistochemical detection of the protein, Fos, was used to identify neurons in the brain activated following a volume load in conscious rabbits with doxorubicin-induced congestive cardiomyopathy. The plasma expander, Haemaccel, was infused intravenously into rabbits for 60 min and significantly increased right atrial pressure, blood pressure and heart rate. The rabbits were perfusion fixed 90 min after the start of the infusion and the distribution of Fos-positive cell nuclei was examined. Compared to control rabbits with heart failure, there was a small significant increase in the number of Fos-positive cell nuclei in the organum vasculosum of the lamina terminalis following volume expansion. In other regions of the brain that were studied in detail, there were no significant increases in Fos production. These included the parvocellular paraventricular nucleus (PVN) of the hypothalamus, the midbrain periaqueductal gray, the nucleus tractus solitarius (NTS), area postrema and the ventrolateral medulla (VLM). In the supraoptic nucleus and the magnocellular PVN, no Fos-positive cell nuclei were present as expected. The median preoptic nucleus, the bed nucleus of the striae terminalis and the diagonal band of Broca contained some Fos but there was no marked difference between volume expanded and control animals. In the anterior cortical and medial subnuclei of the amygdala there was a high concentration of Fos but there was no consistent difference between the two groups. The present findings in heart failure rabbits suggest that most brain regions are not activated sufficiently by the stimulus to elicit Fos expression. The results are in accord with findings showing that sympathetic reflexes initiated by volume expansion are attenuated in heart failure.

Animals↗

PubMed1982

A 14C-2-deoxyglucose analysis of the neural pathways of the limbic forebrain in the rat: II. The hypothalamus.

An attempt was made to characterize the nature of the functional organization of the hypothalamus by observing the patterns of uptake of 14C-2-deoxyglucose (2DG) following electrical stimulation of different regions within the preoptico-hypothalamus in the rat. The experimental paradigm consisted of electrical brain stimulation delivered continuously for periods of 30 sec on and 30 sec off for 45 minutes following injection of 2DG. Brains were removed and processed for autoradiography. Activation of the medial forebrain bundle was noted following stimulation of the nucleus accumbens and lateral preoptico-hypothalamus. Activated fibers could be followed only in a caudal direction through the medial forebrain bundle and into the ventral tegmental area as a result of nucleus accumbens stimulation. Stimulation of the lateral preoptic region or of the anterior half of lateral hypothalamus produced activation of the lateral septal nucleus, lateral habenular nucleus, perifornical region, midline thalamus and ventral tegmental area. Since stimulation of the perifornical hypothalamus significantly activated the rostro-caudal extent of the midbrain cental gray, it is suggested that impulses from the lateral hypothalamus reach the lower brainstem via its connections with the perifornical hypothalamus. Ventromedial hypothalamic stimulation activated only the lateral septal nucleus, cortico-medial amygdala and medial preoptico-hypothalamus, while medial preoptico-hypothalamic stimulation resulted in increased 2DG uptake in the midbrain central gray, thus suggesting that medial hypothalamic impulses reach the brainstem by first ascending to the level of the preoptico-hypothalamus. Mammillary body stimulation orthodromically activated fibers in the mammillothalamic and mammillotegmental tracts and antidromically fibers in the fornix for a short distance.

Amygdala↗

PubMed2001

Studies of the central neural pathways to the stomach and Zusanli (ST36).

The purpose of this morphological study was to investigate the relation between the meridian, meridian points and viscera using neuroanatomical tracers. The common locations of the spinal cord and brain projecting to the stomach and Zusanli were observed following injection of CTB (cholera toxin B subunit) and pseudorabies viruses (PRV-Ba, Bartha strain and PRV-Ba-Gal, galactosidase insertion) into the stomach and Zusanli (ST36). After 4-5 days of survival following injection into twelve rats, they were perfused, and their spinal cords and brains were frozen sectioned (30 microm). These sections were stained by X-gal histochemical, CTB and PRV-Ba immunohistochemical staining methods, and examined with the light microscope. The results were as follows: Commonly labeled medulla oblongata regions were dorsal motor nucleus of vagus nerve (DMV), nucleus tractus solitarius (NTS) and area postrema (AP) following injection of CTB and PRV-Ba-Gal into stomach and Zusanli, respectively. In the spinal cord, commonly labeled neurons were found in thoracic, lumbar and sacral spinal segments. Densely labeled areas were found in lamina IV, V, VII (intermediolateral nucleus) and X of the spinal cord. In the brain, commonly labeled neurons were found in the Al noradrenalin cells/Cl adrenalin cells/caudoventrolateral reticular nucleus, dorsal motor nucleus of vagus nerve, nucleus tractus solitarius, area postrema, raphe obscurus nucleus, raphe pallidus nucleus, raphe magnus nucleus, gigantocellular nucleus, locus coeruleus, parabrachial nucleus, Kolliker-Fuse nucleus, A5 cell group, central gray matter, paraventricular hypothalamic nucleus, lateral hypothalamic nucleus, retrochiasmatic hypothalamic nucleus, bed nucleus of stria terminalis and amygdaloid nucleus. Thus central autonomic center project both to the stomach and Zusanli. These morphological results suggest that there is a commonality of CNS cell groups in brain controlling stomach (viscera) and Zusanli (limb).

Acupuncture Points↗

PubMed1985

A [14C]2-deoxyglucose analysis of the functional neural pathways of the limbic forebrain in the rat. V. The septal area.

The [14C]2-deoxyglucose (2-DG) metabolic mapping technique has been used to identify the regions responding with an augmented rate of metabolism following focal electrical stimulation of various sites within the lateral septal nucleus and medial septal nucleus/diagonal band (MSN/DB) complex in the rat. Since 2-DG uptake has been correlated with rates of functional activity, it was the intention of this study to suggest the anatomical substrates underlying various physiological and behavioral responses elicited by stimulation of the septal area. The results show that stimulation of any region within the lateral septal nucleus produced a profound bilateral activation of both the lateral septal nucleus, as well as the hippocampal formation. While stimulation of a number of different fiber systems associated with the lateral septum could contribute to the observed pattern of labeling, the data suggest that, functionally, a major consequence of such stimulation is the antidromic activation of CA3----lateral septum fibers to axonal branch points, beyond which, orthodromic propagation of the impulse produces activation in CA3 target regions, including subfields CA1 and CA3, as well as the lateral septal nucleus, bilaterally. In addition, regions typically manifesting metabolic activation following stimulation of the lateral septal nucleus included the ipsilateral diagonal band of Broca, nucleus accumbens, lateral preoptic area and lateral hypothalamus, posteriorly, and the prelimbic cortex, anteriorly. Occasionally, target regions of the postcommissural fornix, including the medial mammillary nucleus and anterior thalamic nuclei were also activated following stimulation of the lateral septal nucleus. In contrast to the widespread pattern of activation resulting from stimulation of the lateral septal nucleus, stimulation of the MSN/DB complex produced activation which was largely confined to the medial forebrain bundle. In a final phase of the experiment, afterdischarge activity was elicited by sodium penicillin injection into the lateral septal nucleus. Such treatment produced more widespread 2-DG uptake, including more extensive activation within the lateral septal nucleus, hippocampal formation, amygdala, and thalamus. Additionally, the prefrontal cortex and temporal neocortex were activated.

Animals↗