Hypothalamic Deep Brain Stimulation Influences Autonomic and Limbic Circuitry Involved in the Regulation of Aggression and Cardiocerebrovascular Control in the Göttingen Minipig

&lt;b&gt;&lt;i&gt;Background:&lt;/i&gt;&lt;/b&gt; Deep brain stimulation (DBS) in the ventral tuberal hypothalamus (VTH) is currently under investigation for the treatment of severe obesity. Stimulation impact on a number of closely related hypothalamic neural systems could potentially influence normal hypothalamic function and thereby generate adverse side effects. &lt;b&gt;&lt;i&gt;Objective:&lt;/i&gt;&lt;/b&gt; To assess the feasibility and safety of VTH DBS in a non-primate large animal model. &lt;b&gt;&lt;i&gt;Methods:&lt;/i&gt;&lt;/b&gt; In the VTH of 6 Göttingen minipigs, quadropolar leads were implanted bilaterally (n = 2) or unilaterally (n = 4), using optimized MRI sequences allowing identification of major diencephalic landmarks. Heart rate, weight, behavior and nighttime locomotor activity were recorded throughout the study period. Two of the unilaterally implanted minipigs were examined with [&lt;sup&gt;15&lt;/sup&gt;O]H&lt;sub&gt;2&lt;/sub&gt;O positron emission tomography (PET) scans performed in DBS-off and DBS-on mode. &lt;b&gt;&lt;i&gt;Results:&lt;/i&gt;&lt;/b&gt; VTH DBS elicited an amplitude-dependent increase in heart rate and transient aggressive behavior. PET demonstrated that VTH DBS caused a global increase in cerebral blood flow velocities and decreased mean transit time. &lt;b&gt;&lt;i&gt;Conclusions:&lt;/i&gt;&lt;/b&gt; VTH DBS results in behavioral and physiological changes, which may derive from activation of closely related limbic and autonomic networks. Caution and further studies of longer length should be requested before this procedure is used more widely in humans.</jats:p

An autometallographic technique for myelin staining in formaldehyde-fixed tissue

A new autometallographic (AMG) technique for staining myelin in formaldehyde- or paraformaldehyde- (PFA) fixed tissue is presented. The tissue sections were exposed to AMG development without prior treatment with silver salts. The method was examined on PFA-fixed tissue from mouse, rat, pig, and formaldehyde-fixed human autopsy material. Samples from brain, spinal cord, cranial, and spinal nerves were either cut on a vibratome, frozen and cryostat sectioned, or embedded and microtome sectioned, before AMG development and counterstaining. The AMG-myelin technique results in a specific black/dark-brown staining of myelin in all parts of the CNS and PNS. It works on all species examined, independent of the histological preparation techniques applied. The AMG staining is stable, stays unchanged through decades, allows counterstaining, and has previously been used with immunohistochemical techniques. On perfusion-fixed tissue the technique works without further fixation, but the intensity of the AMG-myelin staining is increased by increased postfixation time. Additionally, immersion fixation has to last for days depending on the size of the tissue block in order to obtain proper myelin staining. The most feasible explanation of the chemical events underlying the AMG-myelin technique is that nano-sized clusters of metallic silver are formed in the myelin as a result of chemical bounds with reducing capacity, exposed or created by the formaldehyde molecule. The AMG method is simple to perform and as specific as the conventional osmium and luxol fast blue stainings. The present technique is thus an effective, simple, inexpensive, and quick myelin staining method of formaldehyde- or PFA-fixed tissue

Supplementary Material for: Hypothalamic Deep Brain Stimulation Influences Autonomic and Limbic Circuitry Involved in the Regulation of Aggression and Cardiocerebrovascular Control in the Göttingen Minipig

Background: Deep brain stimulation (DBS) in the ventral tuberal hypothalamus (VTH) is currently under investigation for the treatment of severe obesity. Stimulation impact on a number of closely related hypothalamic neural systems could potentially influence normal hypothalamic function and thereby generate adverse side effects. Objective: To assess the feasibility and safety of VTH DBS in a non-primate large animal model. Methods: In the VTH of 6 Göttingen minipigs, quadropolar leads were implanted bilaterally (n = 2) or unilaterally (n = 4), using optimized MRI sequences allowing identification of major diencephalic landmarks. Heart rate, weight, behavior and nighttime locomotor activity were recorded throughout the study period. Two of the unilaterally implanted minipigs were examined with [15O]H2O positron emission tomography (PET) scans performed in DBS-off and DBS-on mode. Results: VTH DBS elicited an amplitude-dependent increase in heart rate and transient aggressive behavior. PET demonstrated that VTH DBS caused a global increase in cerebral blood flow velocities and decreased mean transit time. Conclusions: VTH DBS results in behavioral and physiological changes, which may derive from activation of closely related limbic and autonomic networks. Caution and further studies of longer length should be requested before this procedure is used more widely in humans