Recording of ENGs from the nerves innervating the pancreas of a dog during the intravenous glucose tolerance test

Abstract

Electroneurograms (ENGs) from the vagus nerve (VN), the splanchnic nerve (SN) and the pancreatic nerve (PN) innervating the pancreas of a dog, were recorded with chronically implanted 33-electrode spiral cuffs (cuff) before and after the pancreas were stimulated with intravenously (i.v.) administered glucose. In the cuffs platinum electrodes were arranged in three parallel spiral groups containing 11 electrodes on the inner surface. The cuffs had an inner diameter of 2 mm and a length of 18 mm. In a two-year study, the cuffs were implanted into two Beagle dogs and were also used for pancreatic stimulation, although this is not described in this paper. In the VN, the cuff was installed on the nerve at the neck, whilst in the SN, the cuff was installed on the nerve before the celiac ganglion, and in the PN, the cuff was installed on the nerve just before it enters the pancreas. Six months after implantation, when the model of interpretation of the results was developed, three recordings of ENG in each animal were conducted. The first one was conducted in the unstimulated pancreas while the second and the third were conducted 1 and 8 min after a known amount of glucose was i.v. administered. Since the results obtained in both animals were actually quite similar, we present the results obtained in one animal. To evaluate the changes in superficial activity of the nerves, elicited by the administration of glucose, the power spectra corresponding to ENGs, recorded from the nerves before and after the administration of glucose, were integrated within the band of frequencies ranging from 1 to 5 kHz. Accordingly, the magnitude of the integrated power spectrum (MIPS), corresponding to the ENG recorded from the SN before administration of glucose, was 2.863 au. One minute after glucose was administered the value fell to 2.795 au while 8 min after the administration the value returned to 2.8 au. The MIPS corresponding to the ENG recorded from the PN before the administration of glucose was 3.236 au. One minute after the administration the value fell to 2.901 au while 8 min after the administration the value rose to 3.009 au. The MIPS, corresponding to the ENG recorded from the VN before the administration of glucose, was 3.656 au. One minute after the administration the value fell to 3.565 au. Eight minutes after the administration the value rose to 3.689 au. The results show that 1 min after glucose was administered superficial activity in all three nerves was reduced while 8 min after administration the activity in the nerves returned to the same level of activity before the glucose was administered. This information could be effectively used in a further study of pancreatic innervation and its function. Moreover, the results suggest that cuffs could also be useful in recording the ENGs from other nerves of the autonomic nervous system that innervate various glands and internal organs.

Canine pancreatic lipase immunoreactivity concentrations associated with intervertebral disc disease in 84 dogs

“…Pancreatic function and vascular tone are controlled by autonomic nervous system supply acting upon the asymmetric vascular supply of the right and left pancreatic lobes ( Cadet‐Leite 1973 , Neuhuber 1989 , Spaulding 1997 , Rozman et al . 2002 , de Lahunta & Glass 2009 ).…”

“…Pancreatic functions are controlled by the autonomic nervous system, directly and indirectly ( Holmgren & Olsson 2011 , Rozman et al . 2002 , Seoane‐Collazo et al . 2015 ).…”

Reliability of parylene-based multi-electrode arrays chronically implanted in adult rat brains, and evidence of electrical stimulation on contact impedance

“…J. (3) Carbon nanofibers allowed assessment of issues of being focal and minimally invasive, and having enough stiffness for insertion [36]; (4) Laser-cut metal tracks and contacts embedded in silicone rubber in the transverse and longitudinal section of the nerve in front of selected bundles of fibers is a good compromise between resolution and industrial manufacturing [37], pre-strained silicone sheets with multi-contact (up to 33) which reliability was assessed in dogs for six months [38]; (5) TEENI concept [39] is an alternative approach that tends to promote nerve reconstruction in a tube of biocompatible hydrogel along a network of longitudinal planar electrodes in the case of amputation.…”

“…Typically, cuff electrodes are made of two to three metal rings around the epineurium, and most of the further evolutions focused on improving either their selectivity or the signal-to-noise ratio. At least five alternatives have been proposed: (1) flat interface nerve electrodes (FINE) gave promising results, even for long-term recordings [32]; (2) thin-film longitudinal intrafascicular electrodes (tfLIFE), and transverse intrafascicular multichannel electrodes (TIME), whose potential for selective stimulation and recordings was investigated using thin-film polyimide substrates [33][34][35]; (3) carbon nanofibers allowed assessment of focal and minimally invasive issues, with enough stiffness for insertion [36]; (4) laser-cut metal tracks and contacts embedded in silicone rubber in the transverse and longitudinal section of the nerve in front of selected bundles of fibers is a good compromise between resolution and industrial manufacturing [37], and pre-strained silicone sheets with multicontact (up to 33), in which reliability was assessed in dogs for six months [38]; (5) the TEENI concept [39] is an alternative approach that tends to promote nerve reconstruction in a tube of biocompatible hydrogel along a network of longitudinal planar electrodes in the case of amputation.…”

Implantable neurotechnologies: a review of integrated circuit neural amplifiers

“…For example, Rozman et al [112] demonstrated neural recording from the nerves innervating the pancreas and proposed using such recordings to achieve closed-loop controlled secretion of pancreatic hormones. As discussed in the last section, there are no reported applications of neural recording ICs for any chronically implantable PNS neuroprosthesis.…”